an inflammatory periodontal disease

An MWC Pub l i c a t i on Ju l y 2004 / Vo l . 25 , No . 7 ( Supp l 1 )

of Continuing Education in Dentistry®

A Supplement to

2 Hours of CE Credit from Dental Learning Systems

Supported by The Colgate-Palmolive Company© 2004. Medical World Business Press, Inc.

Gingivitis:An InflammatoryPeriodontalDisease

Gingivitis:

Dear Readers:We are grateful to The Colgate-Palmolive Com-

pany for the educational grant that supports this issuebecause it deals with a process that affects most of ourpatients: inflammation in the oral cavity. Under-standing the advances that have been made in iden-tifying all of the reactions that occur with inflamma-tion is of great importance to dentists, dental stu-dents, and dental hygienists. When the inflammatorylesion is recognized in our patients, it becomes imper-ative that a treatment plan to eliminate or reduce thatprocess is implemented. The clinician also must beaware of the recent observations that indicate a possi-ble oral–systemic link in patients with periodontaldiseases who are pregnant; those at risk for cardiovas-cular disease; and those suffering from diabetes.Interestingly, the prevailing theory on coronary arterydisease is the Ross Theory. Russell Ross,a who was adentist and chaired the Department of Pathology atthe University of Washington Medical School, wrotethat atherosclerosis in coronary vessels was an inflam-matory process. Today, more and more research stud-ies are examining the possible mechanisms involvedin linking inflammatory changes in oral tissues to sys-temic manifestations. Those in the profession todayrealize that the presence of gingivitis and periodonti-tis may have far greater implications on total systemichealth than ever imagined before. This issue of TheCompendium should be of great value to everyoneinvolved in the treatment of patients with inflamma-tory changes in the oral cavity.

Sincerely,

Dr. D. Walter CohenChancellor EmeritusDrexel University College of Medicine

Dean EmeritusUniversity of PennsylvaniaSchool of Dental Medicine

Editor-in-ChiefThe Compendium

aRoss R. Atherosclerosis—an inflammatory disease. N Engl J Med. 1999;340:115-126.

Dear Colleagues:One of my mentors during my periodontal

residency at the University at Buffalo gave mekeen insight to the phrase, “Let the [gingival] tis-sue speak.” Careful visual observation wouldassist in describing the delicate tissue changesand begin to create a mental anatomy of thepathologies affecting the periodontium. Sub-sequent evidence-based therapeutic modalitiesled to the pathways toward optimum clinicalhealth.

Fundamental to visual observations were theclassical Latin terms included in this familiarmedley: calor (heat); dolor (pain); tumor(swelling); rubor (redness); and funcio laesa (lossof function). This quintet of periodontal tissuecharacteristics provides visual language of thebiology underlying the tissues through the stagesof disease as well as in health. These terms,known from the earliest medical records, can, oflate, be complemented with clinical researchdata from tissue messengers, also known asinflammatory mediators. Research observationsgive us a new vision and understanding of themechanisms underlying what we can only “see”as clinicians.

We present this special issue of TheCompendium as a reference manual to provideinsight to this important field of dentistry and tobetter prepare you for optimum clinical care ofyour patients.

Sincerely,

C. Yolanda Bonta, DMD, MS, MS

Director of TechnologyProfessional Marketing/

External RelationsAcademic and Professional

RelationsThe Colgate-Palmolive Company

Gingivitis: An Inflammatory Periodontal Disease

Table of Contents

Inflammation, Periodontal Diseases, and Systemic Health 4Abdul Gaffar, PhD; Anthony R. Volpe, DDS

CE 1—A Primer on Inflammation 7Angelo Mariotti, DDS, PhD

CE 2—Periodontal Inflammation: From Gingivitis to Systemic Disease? 16Frank A. Scannapieco, DMD, PhD

CE 3—Cardiovascular Disease and Periodontal Diseases: Commonality and Causation 26Sheilesh Dave, DDS; Eraldo L. Batista Jr, DDS, MSc; Thomas E. Van Dyke, DDS, PhD

CE 4—Evidence that Diabetes Mellitus Aggravates Periodontal Diseases and Modifies the Response to an Oral Pathogen in Animal Models 38

Dana T. Graves, DDS, DMSc; Hesham Al-Mashat, DDS; Rongkun Liu, DDS, PhD

Effectiveness of a Triclosan/Copolymer Dentifrice on Microbiological and Inflammatory Parameters 46Tao Xu, DMD, PhD; Meenal Deshmukh, PhD; Virginia Monsul Barnes, DDS; Harsh M. Trivedi, MS; Diane Cummins, PhD

Rationale for the Daily Use of a Dentifrice Containing Triclosan in the Maintenance of Oral Health 54William DeVizio, DMD; Robin Davies, BDS, PhD

Quiz 58

3Vol. 25, No. 7 (Suppl 1) Compendium / July 2004

Gingivitis:

This supplement to The Compendium was supported by an unrestricted educational grant from The Colgate-Palmolive Company. To order additional copies call 800-926-7636, x180. D518

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The Compendium of Continuing Education in Dentistry® is published monthly with an extra issue in September by Dental Learning Systems. Copyright © 2004.Medical World Business Press, Inc./A division of Medical World Communications, Inc. All rights reserved. No part of this issue may be reproduced in any formwithout written permission from the publisher. Medical World Communications Corporate Officers: Chairman/CEO, John J. Hennessy; President, CurtisPickelle; Chief Financial Officer, Steven Resnick.

The views and opinions expressed in the articles appearing in this publication are those of the author(s) and do not necessarily reflect the views or opinions of the editors, theeditorial board, or the publisher. As a matter of policy, the editors, the editorial board, the publisher, and the university affiliate do not endorse any products, medical tech-niques, or diagnoses, and publication of any material in this journal should not be construed as such an endorsement.

WARNING: Reading an article in The Compendium® does not necessarily qualify you to integrate new techniques or procedures into your practice. The Compendium® expectsits readers to rely on their judgment regarding their clinical expertise and recommends further education when necessary before trying to implement any new procedure.Printed in the U.S.A. D518

Achronic inflammatory disease of the gingiva and periodontiumresults in destruction of gingival connective tissue, periodontal lig-ament, and alveolar bone. Clinically, inflammation is seen as red-

ness, swelling, and bleeding upon probing. However, at molecular and cel-lular levels, the inflammatory process is defined by cellular infiltrates andthe release of a variety of cytokines.1 The main provoking factor thatinduces inflammation of gingival tissue is the presence of bacterial biofilm(dental plaque) on the teeth/gingival interfaces.2 The products of biofilmbacteria, such as lipopolysaccharide (LPS) molecules, are known to initiatea chain of reactions in the tissue leading to host response as well as thedestructive process (Figure).3

Current models of mucosal surfaces of oral, gut, lung, and skin tissue pos-tulate that local bacterial antigens, derived from biofilms on surfaces, regu-late local tolerance, local immune response, and systemic response by wayof an “information relay system” through a series of nuclear factor-kappabeta pathways to synthesize and secrete cytokines and chemokines to regu-late the inflammatory process at local as well as distant sites.4 Evidence isalso accumulating that the predominant cells of the periodontium, gingivalfibroblasts, are capable of producing prostaglandins, interleukins (IL-1beta [β], IL-6, IL-8), tumor necrosis factor-alpha (TNF-α), and inter-feron-gamma (IFN-γ).5 It is hypothesized that these mediators modulateinflammation locally as well as at a distant site of infection.

Is there a rationale for linking the inflammation of gingival tissue andthe pathophysiology of systemic chronic inflammatory diseases? In this sup-plement, two mechanisms are discussed. One presupposes the direct role oforal bacteria or their products in the pathogenesis of atherosclerotic plaquein myocardial infarctions. An alternative explanation is the possible role ofmediators in inflammation initiated by periodontal pathogens in the devel-opment of chronic complications.5-7 There is general agreement that chron-ic diseases, such as atherosclerosis, stroke, and diabetes, are multifactorial inorigin. But there is growing evidence that these diseases are influenced bygingival inflammation and chronic periodontal infections. In a series ofcross-sectional studies, a strong relationship has been found between acute-phase C-reactive protein (CRP) in serum and the severity of periodontaldiseases.8-11 CRP is triggered by infections, trauma, necrosis, and malignan-cy,12 and is also linked to heart disease and diabetes. CRP is synthesized inthe liver in response to proinflammatory cytokines such as IL-1α, IL-1β, andIL-6. TNF-α, IFN-γ, and transforming growth factor also participate in theproduction.

The current therapeutic strategy to control periodontal infectionsinvolves mechanical removal of deposits, both supra- and subgingival. Thisalso could involve the use of topical and systemic antimicrobial agents.There are, however, very few studies to assess the effects of these therapiesconcomitantly with systemic health. Two pilot clinical studies with sub-antimicrobial administration of doxycyline indicated that these regimens

4 Compendium / July 2004 Vol. 25, No. 7 (Suppl 1)

Abdul Gaffar, PhDVice President, Growth Technology

Anthony R. Volpe, DDSColgate Corporate Technology Group

Piscataway, New Jersey

Inflammation,Periodontal Diseases,and Systemic Health

reduced the “marker” of periodontal diseases, aswell as risk markers of acute coronary syndromeand diabetes.12,13

Can topical antimicrobials applied via anoral delivery system (toothpaste, rinse, or gels)also achieve such an outcome? It is believedthat a triclosan/copolymer/fluoride dentifricesystem could provide such a benefit. Triclosan

is a broad-spectrum antibacterial agent thathas been shown to kill oral pathogens at 0.3ppm to 5 ppm. Because of a favorable partitioncoefficient, it can readily penetrate gingivaltissue and reach the target subgingivally.14

Relatively high concentrations of triclosan areretained in the plaque postbrushing (40 ppm

after 2 hours and retained above minimuminhibitory concentration 12 hours postbrush-ing). It is an unusual antibacterial because italso has anti-inflammatory effects. For exam-ple, it inhibits both cyclooxygenase andlipooxygenase pathways at concentrations wellbelow those retained in the dental plaque.15 Ithas also been observed that triclosan inhibitsthe release of prostaglandin E2 from IL-1β–stimulated gingival fibroblasts, as well asreduces the actual production of IL-1β andIFN-γ.16 In long-term studies, topical effects ofspecially formulated triclosan have beenshown to reduce or prevent periodontal diseasein humans.17

Recently, such a formulation was shown tosignificantly improve (P = .05) oral hygiene,gingival health, and periodontal status in agroup of high-risk smokers for 24 months.18

Based on the success of the agent as a topicalantibacterial in the mouth, albeit in a special-ized formulation, it stands to reason to evaluatethe agent for its effect on periodontal inflam-mation concomitant to its effect on systemicinflammation. To confirm this hypothesis,long-term prospective studies will be needed.


Harmful pathogen

Commensal flora Food

LPS

Local tolerance

Local suppression

Local immunization

Systemic tolerance

Cytokines

Systemic response

Systemic immunization

ChemokinesProstanoids

Systemic pathology Intervention

Local Inflammatory Response (biofilm = dental plaque)

CRP

Figure—This illustration shows the local bacterial products that can influence the release of cytokines, which could moderate inflamma-tion at a distant site. It also identifies two possible sites for intervention. Adapted from Hayday A, Viney JL.4

Information Relay from Gingiva to Distant Site

The main provoking factor

that induces inflammation

of gingival tissue is the presence of

bacterial biofilm (dental plaque)

on the teeth/gingival interfaces.

References1. Page RC, Kornman KS. The pathogenesis of human peri-

odontitis: an introduction. Periodontol 2000. 1997;14:9-11.2. Teng YT. The role of acquired immunity and periodontal

disease. Crit Res Oral Biol Med. 2003;14:237-252.3. Haffajee AD, Socransky SS. Microbial etiological agents of

destructive periodontal diseases. Periodontol 2000. 1994;5:78-111.

4. Hayday A, Viney JL. The ins and outs of body surfaceimmunology. Science. 2000;290:97-100.

5. Mustafa M, Wondimu B, Bakhiet M, et al. Induction ofinterferon gamma in human gingival fibroblasts challengedwith phytohaemagglutinin. Cytokine. 2000;12:368-373.

6. Loesche WJ, Lopatin DE. Interactions between periodontaldisease, medical disease and immunity in older individuals.Periodontol 2000. 1998;16:80-105.

7. Grossi SG, Skrepcinski FB, DeCaro T, et al. Treatment ofperiodontal disease in diabetics reduces glycated hemoglo-bin. J Periodontol. 1997;68:713-719.

8. Slade GD, Offenbacher S, Beck JD, et al. Acute-phaseinflammatory response to periodontal disease in the USpopulation. J Dent Res. 2000;79:49-57.

9. Loos BG, Craandijk J, Hoeck FJ, et al. Elevation of systemicmarkers related to cardiovascular diseases in the peripheralblood of periodontitis patients. J Periodontol. 2000;71:1528-1534.

10. Koj A. Initiation of the acute phase response and synthesisof cytokines. Biochim Biophys Acta. 1996;131:84-94.

11. Moshage H. Cytokines and the acute phase response. J Pathol. 1997;181:257-266.

12. Gabay C, Kushner I. Acute phase proteins and other sys-temic responses to inflammation. N Engl J Med. 1999;340:448-454.

13. Brown DL, Lee HM, Kesai K, et al. Effect of sub-antimicro-bial doxycycline on biomarkers in patients with acute coro-nary syndromes [abstract]. J Dent Res. 2003;82(spec iss).Abstract 1443.

14. Lin YJ, Fung KK, Kong BM, et al. Gingival absorption of tri-closan following topical mouthrinse application. Am J Dent.1994;7:13-16.

15. Gaffar A, Scherl D, Afflitto J, et al. The effects of triclosanon mediators of gingival inflammation. J Clin Periodontol.1995;22:480-484.

16. Mustafa M, Wondimu B, Ibrahim M, et al. Effects of tri-closan on interleukin-1 beta production in human gingivalfibroblasts challenged with tumor necrosis factor alpha. EurJ Oral Sci. 1998;106(2 pt 1):637-643.

17. Rosling B, Wannfors B, Volpe AR, et al. The use of a tri-closan/copolymer dentifrice may retard progression of peri-odontitis. J Clin Periodontol. 1997;24:873-880.

18. Kerdvongbundit V, Wikesjö UME. Effect of triclosan onhealing following non-surgical periodontal therapy in smok-ers. J Clin Periodontol. 2003;30:1024-1030.



Angelo Mariotti, DDS, PhDProfessor and Chair of PeriodontologyThe Ohio State University

College of DentistryColumbus, Ohio

After reading this article,the reader should be able to:• describe mast cell

functions.• discuss the three

plasma protein systemsassociated with theinflammatory process.

• cite examples of inflammatory cellularproducts.

• list the features ofchronic inflammation.

• explain the differencebetween regenerationand repair.

Abstract: Inflammation is the localized, protective response of the bodyto injury or infection. The classic clinical signs that characterize inflam-mation are heat, redness, swelling, pain, and loss of function. Duringinflammation, cells and their secreted chemicals attempt to destroy,dilute, or wall off the injurious agent. A series of biochemical eventscause the blood vessels to dilate and become more permeable, resulting inthe activation of the complement, clotting, and kinin systems. The endresult of inflammation is the return of function by the regeneration orrepair of the affected tissue. In some instances, inflammation may con-tinue for a prolonged period of time, producing untoward consequencesfor localized tissue as well as the entire body. The purpose of this articleis to provide a basic and simplified understanding of how the inflamma-tory process functions in the human body.

Learning Objectives

News about inflammation surrounds us. It is no longer confined totextbooks and dental classroom lectures. Today, even the lay presshas suggested that our well-being is inextricably bound to an

absence of inflammation. The interest in inflammation has been heightenedbecause the etiology of many systemic diseases (once thought to be inde-pendent of the inflammatory process) has been associated with some com-ponent of the inflammatory process. Even in dentistry, inflammatory dis-eases can significantly affect tissues of the oral cavity, and, most recently,oral inflammatory processes have been implicated in affecting tissues distantfrom the mouth.

Although most of the recent press on inflammation has emphasized thedeleterious effects it has on the body, it must be noted that without theinflammatory process, life as we know it could not survive. Inflammationinvolves the release of biochemical agents from cells located around vascu-larized tissues that defend the host against infection and facilitate tissuehealing and repair.

The function and stages of the inflammatory process are not difficult tounderstand, but the response of cellular systems to biochemical mediatorsthat regulate the various stages of inflammation is complex. The purpose ofthis article is to provide a basic and simplified understanding of how theinflammatory process functions in the human body.

Acute Inflammatory ResponseInflammation is a nonspecific and immediate cellular and biochemical

response that begins after cellular injury. Cellular injury may occur as a resultof trauma, genetic defects, chemical agents, radiation, microorganisms, etc.In general, the inflammatory process can be divided into mast cell respons-es, activation of plasma protein systems, and the release of cellular products(Figure 1).

Mast CellsMast cells are located in the connective tissues close to blood vessels and

contain a variety of biochemical agents located in intracellular granules.1,2

Immediately after cellular injury, mast cells release preformed biochemical

A Primer onInflammation CE 1CE 1


CE 1

mediators that include histamine, neutrophilchemotactic factor, and the eosinophil chemo-tactic factor of anaphylaxis (Figure 2).Histamine is a vasoactive amine that causes therapid constriction of the smooth muscle cells oflarge blood vessels, dilation of postcapillaryvenules, and increased vascular permeability.This results in elevated pressure in the micro-circulation, which increases exudation of plas-ma, blood cells, and platelets into the surround-ing tissues (Figure 3). As plasma moves into theconnective tissue, the remaining blood flowsmore slowly and becomes more viscous, therebyallowing leukocytes to attach to vessel walls and

squeeze through the spaces created by endothe-lial retraction (Figure 3). Two chemical signals,the neutrophil chemotactic factor and theeosinophil chemotactic factor of anaphylaxis,cause the unidirectional movement of neu-trophils and eosinophils. The first leukocytes atthe inflamed site are neutrophils. These cellsconstitute almost 70% of the peripheral bloodleukocytes and are responsible for killingmicroorganisms (Table 1) as well as the phago-cytosis of dead cells and cellular debris. Becauseneutrophils have a short life span, anothergroup of phagocytic cells (ie, monocytes andmacrophages) perform similar functions to neu-trophils but are present for longer periods oftime. Eosinophils are also attracted to theinflamed site and, in addition to being phago-cytic, can control the mediators released frommast cells. In addition to the release of pre-formed biochemical mediators, mast cells alsosynthesize leukotrienes, prostaglandins, andplatelet-activating factor. Leukotrienes are pro-duced from arachidonic acid and increase vas-cular permeability and neutrophil chemotaxisin a slower and more prolonged response whencompared to histamines. Similar to leuko-trienes, prostaglandins are derived from arachi-donic acid and increase vascular permeabilityand neutrophil chemotaxis. Prostaglandins alsoinduce pain and can suppress the release of his-tamine from mast cells. Platelet-activating fac-tor is derived from plasma membrane phos-phatidylcholine and enhances vascularpermeability and activation of platelets.

Table 1—Mechanisms Used by Neutrophils to Kill Microorganisms

Oxygen-independent mechanismsAzuoocidinBacterial (permeability-inducing) proteinCathepsin GDefensinsElastaseLactoferrinLysozymeMyeloperoxidaseProteinase 3Oxygen-dependent mechanismsChloraminesHydrogen peroxide (H202)Hydroxyl radicalsHypochlorous acidSinglet oxygenSuperoxide anion

Acute Inflammatory Process

Cellular injuryTrauma, genetic or immune defects, chemical agents, microorganisms, temperature extremes, ionizing radiation, etc

Activation of plasma systems

Release of cellular products

Mast cell degranulation Histamine, leukotrienes, prostaglandins, platelet-activating factor

Complement, clotting, kinin

Histamine, complement, kinins, leukotrienes, prostaglandins, neuropeptides, nitric oxide, platelet-activating factor, tumor necrosis factor, interleukins, granulocytes, monocytes/ macrophages, lymphocytes, platelets, endothelial cell

Figure 1—Relationship of mast cell plasma systems and cellular products during acute inflammation.


CE 1

Plasma Protein Systems Three important plasma protein systems

mediate the inflammatory process. The comple-ment system,3 the clotting system,4 and the kininsystem,5 all consist of a series of inactiveenzymes that are converted through a cascadeof steps to active enzymes. Most components ofthese systems have limited half-lives becausethey are rapidly inactivated by other proteinsfound in the bloodstream.

The 10 proteins that constitute the comple-ment system comprise approximately 10% ofall serum proteins in the circulation. The com-plement system can be activated byantigen–antibody complexes (classical path-way), bacterial components (alternative path-way), and specific plasma proteins (alternativepathway) (Figure 4). Many of the complementsubcomponents are biochemical mediators thataugment inflammation by leukocyte chemo-taxis, degranulation of mast cells, opsonizationof bacteria, and the creation of pores in plasmamembranes. Similar to the complement system,the clotting system can be activated throughtwo pathways called either the extrinsic orintrinsic pathway (Figure 5). The clotting sys-tem can be activated by substances (eg, colla-gen, proteinases, kallikrein, bacterial endotox-ins, etc) that are released during tissue

destruction. The functions of the clotting sys-tem during inflammation include: preventingthe spread of infection and inflammation;localizing microorganisms and debris at the siteof phagocytosis; clot formation to stop bleed-ing; clot formation to form a scaffold for repairand healing; chemotaxis of neutrophils; and

increased permeability of the vasculature.Perhaps the least known of the plasma proteinsystems is the kinin system (Figure 6). The pri-mary molecule of the kinin system isbradykinin. In low doses, bradykinin acts toincrease vascular dilation and permeability,stimulate smooth muscle contraction, activateleukocyte chemotaxis, and induce pain.

The complement, clotting, and kinin sys-tems are all tied together through a mixture ofinteractions in which a protein from one sys-tem can activate one or both of the other plas-ma protein systems. The interconnections

Leukotrienes (SRS-A)

Prostaglandins (E-series)Eosinophil

chemotactic factor

Histamine Neutrophil chemotactic

factorVascular effects

Eosinophils attracted

to site

Neutrophil attracted

to site

Dilation, increased

permeability

Exudation Phagocytosis Phagocytosis

Inhibition of vascular

effects

Vascular effects

Vascular effects

Dilation, increased

permeability

Dilation, increased

permeability

Exudation Exudation

Pain

Degranulation(immediate response)

Synthesis(long-term response)

Plasma membrane

Injury

Interleukin-1lgE-mediated mechanisms

Activated complement(C3a and C5a)

Granules

Nucleus

Acute Inflammatory ProcessMast Cell Degranulation

Figure 2—Effects of degranulation (left) and synthesis (right) by mast cells. Adapted from McCance KL, Huether SE, eds.Pathophysiology—The Biologic Basis for Disease in Adults and Children. 4th ed. Philadelphia, Pa: Mosby; 2002:200.

Three important plasma

protein systems mediate the

inflammatory process: complement,

clotting, and kinin systems.


CE 1 between the three systems can occur throughthe effects of plasmin, kallikrein, clotting fac-tor XI, Hageman factor (clotting factor XII),and complement fragments, as well as othermolecules in the plasma protein systems(Figure 7). One example that demonstrateshow the plasma systems are interrelatedrevolves around plasmin. More specifically,plasmin digests fibrinogen and fibrin, activatesC1 to form C1 esterase (classical complementpathway), activates the Hageman factor (stim-ulates kinin production), and cleaves C3 toproduce anaphylatoxic and chemotactic C3fragments.

Cellular ProductsHost cells produce a myriad of soluble pro-

teins that act directly on proteins, cells, orinvading microorganisms and, ultimately, con-tribute to the defense of the body.6-10 Theinflammatory factors have been identified by anumbing array of acronyms (eg, CSF, MAF,MIF, PDGF, ENA, MCP, IL, TNF, ICAM, INF,PAF, etc) and unless one is familiar with theseproteins (and acronyms), understanding theinflammatory process can be confusing andfrustrating. The diverse number of cellularproducts can be simplified into four categories:cytokines, hormones, mediators, or growth fac-tors. A cytokine is a low-molecular-weight,biologically active protein that alters the func-tion of the cell that released it (autocrine) orthe function of adjacent cells (paracrine).Cytokines can be synergistic (the combinedactivity exceeds the sum of individual activi-ties) or antagonistic (inhibitory). Individual

cytokines are pleiotropic (diverse biologicalroles), whereas different cytokines may havesimilar biological activity. As a result,cytokines have a broad variety of actions com-bined with functional redundancy within theinflammatory system.6-9 Examples of cytokinesare the interleukins. Hormones are biological-ly active molecules that are released into thebloodstream and stimulate functional activityof cells distant from the site of secretion.10 Anexample of a hormone is insulin. Mediators areproteins that are found in the plasma proteinsystems as well as agents released from mastcells.1,2 An example of a mediator is histamine.

Growth factors are a complex family of signalmolecules that regulate differentiation, prolif-eration, growth, and maturation of cells.7 Anexample of a growth factor is transforminggrowth factor.

With the baffling collection of inflammato-ry molecules, which of these molecules are nec-essary and required for the inflammatoryprocess? A simple answer to this question isthat all inflammatory molecules are important;however, a closer inspection of the inflamma-

The interest in inflammation has

been heightened because the

etiology of many systemic diseases has

been associated with some component

of the inflammatory process.

Table 2—Inflammatory Molecules and Their FunctionsMolecules Functions*Chemokines Chemotactic, activate cells, � cytokine releaseComplement Opsonize, chemotactic, anaphylatoxinIntercellular adhesion molecules Promote adhesion of cells to endotheliumInterferon Antiviral protection, activation of macrophagesInterleukins Chemotactic, mitogenic, cytokine release, � immune/inflammatory cellsKinins SM contraction, � permeability, chemotactic, painLeukotrienes SM contraction, � permeability, chemotacticLymphokines Inhibits macrophage migration, � phagocytosisPlatelet-activating factor � permeability, leukocyte adhesionProstaglandins SM contraction, � permeability, chemotactic, painTransforming growth factor Chemotactic, cytokine release, � fibroblastsTumor necrosis factor Cytokine release, � phagocytosis, � macrophagesVasoactive amines SM contraction, � permeability, chemotactic

*Represents only a partial list of functions of cellular agents. SM = smooth muscle; � = increased.


CE 1

Figure 3—Sequence of events in the process of inflammation. Adapted from McCance KL, Huether SE, eds. Pathophysiology—TheBiologic Basis for Disease in Adults and Children. 4th ed. Philadelphia, Pa: Mosby; 2002:199.

Sequence of Events in the Inflammatory Process

tory process suggests that this complex system isnot fully understood, so therefore we cannotaccurately answer the question. If one considersthe functional redundancy of many cytokinesas well as the fact that investigators have muchto learn about the cellular, molecular, biochem-ical, and genetic components of inflammation,it becomes difficult to identify those moleculesthat are both required and necessary for a par-ticular inflammatory event. Until the timecomes when essential roles of regulatory mole-cules during inflammation can be recognized, acontinued understanding of major categories ofinflammatory molecules is necessary. Table 2provides a partial list of inflammatory cellularproducts and their functions.

Chronic InflammationChronic inflammation is generally consid-

ered an inflammatory process that lasts for aprolonged period of time (ie, weeks, months,or even years). Although there is no cleardividing line between acute and chronicinflammation, the extended time frame forchronic inflammation is a result of persistentstimuli from causative agents. For example, in

the oral cavity, periodontal diseases are oftenconsidered chronic inflammatory processesbecause of the difficulty of eliminating oralbacteria via host defenses. Dental biofilms (ie,

plaque) provide a shelter for microorganismsto grow and proliferate and, in turn, releasebacterial products while continually provokingan inflammatory host-cell response.

The histological appearance in chronicinflammation is characterized by a mixedinflammatory infiltrate consisting predomi-nantly of lymphocytes, macrophages, and plas-ma cells. In addition, there is a proliferation offibroblasts and vascular elements in theinflamed tissues that result in an increased

In the oral cavity, periodontal

diseases are often considered

chronic inflammatory processes

because of the difficulty of

eliminating bacterias via host defenses.


CE 1 ALTERNATIVE PATHWAYCLASSIC PATHWAY

Antigen–antibody complexes Stabilized by polysaccharides

in bacterial cell wall

C1q,r,s

C3 Convertase

Minor anaphylatoxin

Terminal components

C1q,r,s

Kinin-like activity

C4aC4

C2b

C1, 4bC2

Anaphylatoxin C3a

C1, 4b,2a

Anaphylatoxin chemotactic factor

C5a

C5 Convertase

C3

C5C1, 4b,2a,3b

C5b

Membrane attackcomplex

C3

C3bFactor B

Factor D C3b, B

BaC3b, Bb

ProperdinC3b, Bb, P

C3b, Bb, P, C3b

C3a

C5a

C6

C5b-6C7

C8

C9 (≤14 monomers)

C5b-7

C5b-8

C5b-9

amount of connective tissue. Both T-helpercells and macrophages are important cells ininitiating a chronic inflammatory response.During chronic inflammation, the activatedmacrophages will release numerous secretoryproducts11 (eg, neutral proteases, acid hydro-lases, plasminogen activators, nitric oxide,interferons, complement components, fibro-nectin, interleukins, and angiogenesis factors)that, in combination with other host cells (ie,neutrophils, eosinophils, T-cells, fibroblasts,mast cells, epithelial cells, etc), may cause sig-nificant local tissue destruction. What ulti-mately results is a healing process that oscil-

lates between tissue destruction and tissueregeneration, often ending in tissue repairinstead of tissue regeneration. This incompletewound healing may result in a permanent lossof function.

During chronic inflammation, the capacityto assemble this type of inflammatory environ-ment places the host tissue under continualstress to destroy the target stimuli. Moreover,the continued production of chemical agentsfrom host cells may not only affect local tis-sues, but may also affect tissues distant fromthe site where chemical mediators are beingproduced.

Figure 4—Pathways of activation of the complement cascade. Complement components are cleaved into fragments, or subcomponents(denoted by lowercase letters), during activation. Many of the subcomponents are biochemical mediators of inflammation. The largeractivated fragment is usually converted into an active enzyme (indicated by the bar above the fragment) and forms a complex with theproceeding components in the cascade. The classic pathway usually is activated by antigen–antibody complexes through componentC1, whereas the alternative pathway is activated by many agents, such as bacterial polysaccharides, through component C3b. Bothpathways produce C3 convertases and C5 convertases, which are enzymatically active complexes that activate C3 and C5, respectively.Adapted from McCance KL, Huether SE, eds. Pathophysiology—The Biologic Basis for Disease in Adults and Children. 4th ed.Philadelphia, Pa: Mosby; 2002:203.


CE 1

Collagen or other activatorsInjured cells

Extrinsic pathway Intrinsic pathway

XIIa XII

X Xa

Prothrombin Thrombin

Va Phospholipid

Fibrinogen Fibrin + fibrinopeptide monomer

Fibrin polymer

Acute Inflammatory ProcessActivation of Plasma System (clotting system)

Collagen or other activators

Hageman factor XII

XIIa Prekallikrein activator

Prekallikrein Kallikrein

Kininogen

Vasodilation Vascular permeability

Pain

Bradykinin

Coagulation cascade

Acute Inflammatory ProcessActivation of Plasma System (kinin system)

Figure 5—Coagulation cascade. During activation of the coagulation cascade, several components are converted from inactive to activeforms. Adapted from McCance KL, Huether SE, eds. Pathophysiology—The Biologic Basis for Disease in Adults and Children. 4th ed.Philadelphia, Pa: Mosby; 2002:205.

Figure 6—Plasma kinin cascade. Adapted from McCance KL, Huether SE, eds. Pathophysiology—The Biologic Basis for Disease inAdults and Children. 4th ed. Philadelphia, Pa: Mosby; 2002:206.


CE 1

Hageman factor XII

XIIa

Prekallikrein activator

Prekallikrein

Kininogen

Bradykinin

Kallikrein

Intrinsic pathway

Plasminogen

Prothrombin

PlasminFibrinogen

Thrombin

Fibrin Fibrinopeptides

C1 C1

C4, 2 C4b, 2a

C3 C3b + C3a

C5 C5b + C5a

C6, C7, C8, C9 C5b - 9

COMPLEMENT SYSTEM

CLOTTING SYSTEM KININ SYSTEM

+

Acute Inflammatory ProcessActivation of Plasma System

Figure 7—Interaction of the complement, clotting, kinin, and fibrinolytic (plasmin) systems. Adapted from McCance KL, Huether SE,eds. Pathophysiology—The Biologic Basis for Disease in Adults and Children. 4th ed. Philadelphia, Pa: Mosby; 2002:207.

Tissue Regeneration or RepairTissue destruction is a consequence of the

inflammatory process, but it is followed byregeneration or repair. Regeneration is thereproduction or reconstitution of a lost orinjured part of the tissue, and usually occurs ifthe tissue damage is minor. Tissue repair ischaracterized by wound healing that does notfully restore the architecture or function of thedamaged tissue, and occurs when there isextensive tissue destruction. Repair concludesin scar tissue formation. Both regeneration andrepair involve the dissolution of fibrin clotsand the removal of toxic agents and particulatematter to prepare the lesion for wound healing.During the reconstructive phase of woundhealing, granulation tissue contains fibroblastsand newly synthesized compounds (eg, colla-gens) of the extracellular matrix. After the

reconstructive phase, collagen deposition, tis-sue regeneration, or scar formation and woundcontraction define the maturation phase ofwound healing.

Systemic Effects of InflammationThe most common systemic effects of

inflammation include fever and leukocytosis(abnormally high white blood cell count);however, in particular circumstances, inflam-mation can do more harm than good. Forexample, destructive forms of inflammationcan affect joints (rheumatoid arthritis), thekidney (glomerulonephritis), blood vessels(vasculitis), cardiac blood vessels (atheroscle-rotic lesion development), the pancreas (dia-betes mellitus), and the periodontium (peri-odontal diseases). It has been hypothesizedthat in the periodontium, the dentogingival


CE 1surface area of individuals with periodontitis(8 to 20 square centimeters12) is responsible forthe release of cytokines that adversely affecttissues distant from the periodontium. Al-though recent data have suggested that peri-odontal inflammation may influence distanttissues, the functional relationship betweenperiodontal inflammation and systemic diseaseremains to be elucidated.13

ConclusionThe inflammatory process occurs in vascu-

lar tissue and is a biochemical and cellularprocess that occurs approximately in the samemanner regardless of the stimulus. On injury,blood vessels dilate and become more perme-able, resulting in increased blood flow andleakage of plasma and cells into the extracellu-lar matrix. The cells and platelets carry outtheir functions with the support of the threemajor plasma protein systems. Moreover,inflammation functions to destroy and removenoxious agents, confine the injurious agentsfor efficacious removal, limit systemic effects ofcellular agents, enhance the immune response,and promote wound healing. Therefore, thebiologic significance of inflammation is pri-marily associated with the defense of the bodyfrom injury and infection.

References1. Brown NJ, Roberts LJ II. Histamine, bradykinin and their

antagonists. In: Hardman JG, Limbird LE, eds. Goodman andGilman’s The Pharmacologic Basis of Therapeutics. 10th ed.New York, NY: McGraw-Hill; 2001:645-667.

2. Marrow JD, Roberts LJ II. Lipid-derived autocids.Eicosanoids and platelet-activating factor. In: Hardman JG,Limbird LE, eds. Goodman and Gilman’s The PharmacologicBasis of Therapeutics. 10th ed. New York, NY: McGraw-Hill;2001:668-685.

3. Bhole D, Stahl GL. Therapeutic potential of targeting thecomplement cascade in critical care medicine. Crit CareMed. 2003;31(1 suppl):S97-S104.

4. Opal SM. Interactions between coagulation and inflamma-tion. Scand J Infect Dis. 2003;35:545-554.

5. Campbell DJ. The kallikrein-kinin system in humans. ClinExp Pharmacol Physiol. 2001;28:1060-1065.

6. Takashiba S, Naruishi K, Murayama Y. Perspective ofcytokine regulation for periodontal treatment: fibroblastbiology. J Periodontol. 2003;74:103-110.

7. Werner S, Grose R. Regulation of wound healing by growthfactors and cytokines. Physiol Rev. 2003;83:835-870.

8. Hanada T, Yoshimura A. Regulation of cytokine signaling andinflammation. Cytokine Growth Factor Rev. 2002;13:413-421.

9. Gemmell E, Marshall RI, Seymour GJ. Cytokines andprostaglandins in immune homeostasis and tissue destructionin periodontal disease. Periodontol 2000. 1997;14:112-143.

10. Mariotti A. Sex steroid hormones and cell dynamics in theperiodontium. Crit Rev Oral Biol Med. 1994;5:27-53.

11. Klimp AH, de Vries EG, Scherphof GL, et al. A potentialrole of macrophage activation in the treatment of cancer.Crit Rev Oncol Hematol. 2002;44:143-161.

12. Hujoel PP, White BA, Garcia RI, et al. The dentogingivalepithelial surface area revisited. J Periodont Res. 2001;36:48-55.

13. Proceedings of the periodontal-systemic connection: a state-of-the-science symposium. Bethesda, Maryland; April 18-20, 2001. Ann Periodontol. 2001;6:1-224.

There has been increasing attention paid in recent years to the possi-bility that oral bacteria and oral inflammation, particularly peri-odontal diseases, may influence the initiation and/or progression of

several systemic disease processes. This, of course, is not a novel concept.Indeed, the focal-infection hypothesis, which grew from the principles ofinfectious disease first established by Koch and Pasteur in the mid-19thcentury, put forth the notion that the invasion of the bloodstream by bac-teria from a localized infection (such as periodontal diseases) could spreadto distant organs and tissues to cause disease.1-3 In fact, this hypothesis wasso convincing to practitioners of the time that tonsillectomy and full-mouth extraction enjoyed widespread implementation to treat many dis-eases, regardless of whether or not infection could be proven to be thecause. However, because it became clear that it was impossible to correlatewith confidence a particular systemic disease with a preceding oral infec-tion or dental procedure, the focal-infection hypothesis fell from favor bythe middle of the 20th century. Yet, interest in the systemic effects of peri-odontal infection was reignited in the early 1990s by a series of case-con-trol and other epidemiologic studies that demonstrated statistical associa-tions between poor oral health and several systemic diseases. The goal ofthis article is to describe the biologically plausible circumstances thatunderlie these potential associations. The reader is further referred torecent definitive reviews on the pathogenesis of periodontal disease for spe-cific details that are beyond the scope of this article.4,5

The periodontium responds to the tooth-borne biofilm, long known asdental plaque, by the process of inflammation. Plaque is composed of


Frank A. Scannapieco, DMD, PhD

ProfessorDepartment of Oral Biology

School of Dental MedicineState University of New York at

BuffaloBuffalo, New York

Abstract: There has been a resurgence of interest in recent years in thesystemic effects of oral infections such as periodontal diseases. The studyof the various means by which periodontal infections and inflammationmay influence a variety of systemic conditions is collectively referred to asperiodontal medicine. The periodontium responds to tooth-borne biofilm(dental plaque) by the process of inflammation. Dental biofilms release avariety of biologically active products, such as bacterial lipopolysaccha-rides (endotoxins), chemotactic peptides, protein toxins, and organicacids. These molecules stimulate the host to produce a variety of respons-es, among them the production and release of potent agents known ascytokines. These include interleukin-1 beta, interleukin-8, prosta-glandins, and tumor necrosis factor-alpha. There is a spectrum of peri-odontal response to these molecules, from mild gingivitis to severedestructive periodontitis. These and other host products and responsesmay influence a variety of important disease pathways, including athero-sclerosis, mucosal inflammation, and premature parturition. The pur-pose of this article is to review the possible biological pathways by whichperiodontal diseases may influence these disease processes.

PeriodontalInflammation: From Gingivitis toSystemic Disease?

After reading this article,the reader should be able to:

• gain insight into thepathogenic mecha-nisms responsible forgingival inflammation.

• discuss plausible mech-anisms that mayexplain associationsbetween gingival andperiodontal inflamma-tion and systemic dis-ease.

• describe oral therapeu-tic interventions thatmay positively influ-ence systemic health.

Learning Objectives

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Vol. 25, No. 7 (Suppl 1) Compendium / July 2004

numerous bacteria, comprising over 400species, which tenaciously adhere to the toothsurface.6 Scientists are now beginning to under-stand the complex molecular interactions thatoccur, for example, between the bacteria andsalivary pellicle that coats the tooth, andbetween gram-positive cocci of early plaqueand gram-negative filamentous bacteria thatpopulate the tooth as plaque matures.7 Recentwork has elucidated complex signaling path-ways (referred to as quorum sensing) betweenbacteria, mediated by soluble chemicals pro-duced by the bacteria that control biofilmdevelopment.8 It is anticipated that this knowl-edge will eventually yield sophisticated strate-gies to limit the pathogenic potential of dentalplaque.

Within a few hours of meticulous toothcleaning, bacteria colonize the tooth surfaceprimarily around the gingival margin and inter-dental spaces (Figure 1).9 The developingbiofilm releases a variety of biologically activeproducts, including lipopolysaccharides (endo-toxins), chemotactic peptides, protein toxins,and organic acids.4 These molecules diffuse intothe gingival epithelium to initiate the hostresponse that eventually results in gingivitisand, in some circumstances, inflammatory peri-odontal diseases.4 Clinically, gingivitis is char-acterized by a change in color—from normal

pink to red—with swelling and, often, sensitiv-ity and tenderness.10 Gentle probing of the gin-gival margin typically elicits bleeding.10

Because gingivitis is often not painful, it mayremain untreated for many years.

Epidemiologically, the prevalence of gingivi-tis in non-Hispanic whites is approximately50% of the population, with up to 63% inMexican Americans showing clinical signs ofthe disease.11 It is quite possible that this rate issomewhat understated because it is possible thatgingivitis, in its most nascent form, is clinicallyundetectable. Periodontitis affects approximate-ly 35% of dentate US adults 30 to 90 years ofage, with 21% having a mild form and 12%having a moderate or severe form of the dis-ease.12 Thus, gingivitis is much more widespreadthan periodontitis in the US population.

Pathogenic Mechanisms of Gingival Inflammation

Histopathologically, gingival inflammationpresents as a spectrum of severity in humans.7

In a relatively small subset of the population,the gingiva are virtually devoid of inflammato-ry infiltrate, the so-called “pristine gingiva”(Figure 2).7 These subjects practice impeccableoral hygiene and demonstrate no clinical signsof inflammation. More widespread would bethe “normal healthy gingiva,” which demon-

17

CE 2Figure 1—Biochemical events in periodontal disease. Pristinegingiva are not exposed to significant numbers of plaquemicroorganisms to yield a hostresponse. Few signs of acuteinflammation or cellular infiltrateare noted.

Compendium / July 2004 Vol. 25, No. 7 (Suppl 1)

strates a mild-to-moderate inflammatory infil-trate. Clinically, these two conditions wouldappear indistinguishable in that the tissueswould appear quite healthy.

Probably most prevalent in the populationis established gingivitis that is associated with amore widespread biofilm and clear clinicalsymptomology (redness, swelling, and bleed-ing), and histopathologically showing signifi-cant inflammatory infiltration (Figure 3).7

The most severe form of periodontal dis-eases results in the destruction of the periodon-tal ligament and supporting osseous tissue and,ultimately, exfoliation of the teeth. Perio-dontitis is associated with extensive formationof biofilm dominated by anaerobic, gram-nega-tive bacteria and spirochetes.13

As mentioned previously, initial dentalplaque bacteria (typically gram-positive cocciand filaments) release a variety of chemicalcompounds during their normal metabolism(organic acids, chemotactic peptides, etc).These products are soluble and penetrate thesuperficial layers of the sulcular epithelium.These substances signal the epithelium of thegingiva to produce a variety of biologicallyactive mediators, most prominently cytokines

such as interleukin-1 beta (IL-1β), interleukin-8 (IL-8), prostaglandins, tumor necrosis factor-alpha (TNF-α), and matrix metalloproteinases(Figure 4). These products influence a numberof cellular processes, including the recruitmentand chemotaxis of neutrophils to the site, withincreased permeability of the gingival vesselsthat results in extravasation of plasma proteinsfrom the blood vessels into the tissue. Theepithelium also responds by induction of innatedefense systems, which include the productionof antimicrobial peptides, such as defensins,calprotectin, etc.14 In addition, the salivarydefense system works to limit bacterial growththrough the flushing action of simple fluid flowthat clears bacteria from the oral surfaces, bac-terial-aggregation factors, antimicrobial pro-teins, etc.15

Should the dental plaque biofilm continueto grow and expand to populate the subgingivalspace, these noxious compounds will stimulatethe epithelium to produce bioactive mediators,resulting in further recruitment of a variety ofcell types, including neutrophils, T-cells,monocytes, etc (Figure 5). The resulting estab-lished or chronic gingivitis is the most preva-lent type of gingival inflammatory lesion in thepopulation as a whole. Thus, continued exacer-bation of the process results in signaling ofunderlying cell types, including fibroblasts, toincrease production of proinflammatory cyto-kines in the tissues. Host systemic responses tothis insult also can be documented. For exam-ple, evidence of specific antibodies to oralorganisms can be demonstrated in peripheralblood. Also, the acute-phase response is associ-

18

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Figure 2—Left panel: Pristine gingiva is found in subjects withimpeccable oral hygiene and minimal plaque. Gingival tissues arefree of clinical signs of inflammation, and tissues are essentiallyfree of inflammatory infiltrate. Right panel: Early gingivitis isfound in subjects with some plaque formation. While the gingivaltissues are free of clinical signs of inflammation, a mild inflam-matory infiltrate is evident, consisting of vasculitis and the pres-ence of neutrophils.

Figure 3—Left panel: In the absence of effective plaque control, arobust inflammatory response results in clinical signs of inflamma-tion (redness, edema, bleeding) and a significant inflammatoryinfiltrate, including neutrophils, lymphocytes, and evidence of col-lagen breakdown. Signs of periodontal attachment loss or alveolarbone loss are not evident. Right panel: The inflammatory responseresults in marked collagen breakdown, periodontal attachment andalveolar bone loss, and clinical signs of inflammation.

Established gingivitis, most

prevalent in the population,

is associated with more widespread

biofilm and clear symptomology.


CE 2ated with gingival inflammation, including theproduction of C-reactive protein (CRP), fi-brinogen, complement, etc, by both local cellsand the liver.16,17 These proteins not only pos-sess biological activities that may further exac-erbate the inflammatory response, they mayalso impact the initiation or progression of sys-temic disease processes, such as atherosclero-sis.18,19

To this point, rigorous tooth cleaning andoral hygiene procedures would reverse thecourse of gingivitis and return the periodon-tium to a healthy state.20 Unfortunately, how-ever, many people fail to maintain adequatehygiene and so the process of inflammationoften continues unchecked for years.

In some individuals, for reasons that are notentirely clear, the inflammatory processexpands to involve the breakdown of collagenin periodontal ligament and bone resorption,resulting in periodontitis (Figure 6). The rate ofbreakdown varies between individuals. It hasbeen suggested that there are underlying genet-ic mechanisms or other risk factors (eg, smok-ing, diabetes, stress, etc) that provoke theseprocesses in certain people and not in others.We’ve heard lately of polymorphisms and vari-ous genes that control, for example, interleukinor fibrinogen synthesis. There is an ongoingscientific effort to determine the role of host

genetics in the susceptibility to periodontalinfection.21

Gingival Health and BacteremiaA consequence of this inflammatory process

is ulceration of the gingival sulcular epitheli-um, which allows bacterial translocation fromthe sulcus into the bloodstream. The surfacearea of the periodontal ligament has been cal-culated to cover about 75 square centimeters.Thus, a person having 50% horizontal boneloss and inflamed pocket epithelium wouldhave a wound surface of approximately 30 to 40square centimeters. Such a wound surfacewould likely increase the risk for bacterialtranslocation when compared to a healthy peri-odontium. In the most prevalent periodontaldisease, established gingivitis, pockets of 4 to 5millimeters may translate into a gingival woundsurface area of 10 to 20 square centimeters.Considering that many people go a long timewithout having gingivitis treated, this chronicinflammatory condition may promote continu-ous, low-grade chronic bacteremia. Severalstudies have indeed shown that the incidenceof bacteremia is elevated in subjects withincreasing severity of gingival inflammation.22,23

When using rather insensitive bacterial culturetechniques, bacteremia could be detected evenin subjects with clinically healthy gingiva. The

Figure 4—Bacteria in dentalplaque release biologically activecomponents, includinglipopolysaccharides, chemotacticpeptides, and fatty acids. Thesecomponents signal gingivalepithelial cells to release proin-flammatory cytokines that dif-fuse into the underlying connec-tive tissues to stimulate acutevasculitis, which leads to dilationof blood vessels and extravasa-tion of plasma components intothe connective tissue compart-ment. Chemotactic peptides sig-nal white cells to interact withand stick to vascular endotheli-um, after which the neutrophilsenter the connective tissues. Inaddition to the inflammatoryresponse, the host attempts toclear itself of microorganisms byresponding to these signals withepithelial production of antimi-crobial peptides. Saliva alsoaffords numerous antimicrobialmechanisms to protect the host.

19


Figure 5—Increased numbersand increasing diversity of bacte-ria in dental plaque continue torelease biologically active com-ponents that increase the intensi-ty and spread of the inflammato-ry response. Increased numbersof neutrophils, monocytes, andmacrophages infiltrate the tis-sues to release more diversecytokines and prostaglandinsthat exacerbate the inflammatoryresponse. Lymphocytes (T-andB-cells) and plasma cells alsoinfiltrate, the latter releasing anti-bodies against the microorgan-isms that may also cross-reactwith the host tissues. The acute-phase response (including pro-duction of acute-phase proteinssuch as CRP, serum alpha amy-loid A, and fibrinogen) also isevident.

use of more sensitive molecular techniques,such as the polymerase chain reaction,24,25

would likely prove bacterial translocation fromthe periodontium to be even more commonthan presently appreciated. While most studiesof dentally related bacteremia have centeredaround purposeful activities such as tooth-brushing, periodontal probing, and toothextraction, it is possible that while participat-ing in daily activities (chewing, speaking,habits, etc), minor disruptions to gingivalintegrity occur in a significant number of indi-viduals with gingival inflammation.

Gingival Inflammation: Pathways of Systemic Effects

Oral bacteria and gingival inflammationmay theoretically influence systemic healththrough four potential pathways: bacteremia,systemic dissemination of locally producedinflammatory mediators, provocation of anautoimmune response, and aspiration or inges-tion of oral contents into the gut or airway(Figure 7). Low-grade but persistent bacteremiamay allow oral bacteria to aggregate plateletsthrough receptor-ligand interactions. Studieshave shown that infusing rabbits with aggregat-ing bacteria caused significant hemodynamicchanges, acute pulmonary hypertension, andcardiac abnormalities, including ischemia.26

This very provocative work suggests that bac-teremia of oral origin may have serious implica-tions for systemic health.

Several inflammatory mediators can bemeasured as being elevated in peripheral bloodin subjects with periodontal disease,17 suggest-ing that periodontal inflammation either con-

tributes directly to the elevation of the concen-tration of these substances in peripheral bloodor signals distant organs (eg, the liver) to pro-duce them. The liver could respond, for exam-ple, through the acute-phase response by pro-ducing CRP, fibrinogen, etc. These proteinsmay have deleterious effects on other targetorgans (eg, heart, brain) by modulating diseaseprocesses such as atherosclerosis.

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20

Interest in the systemic effects of

periodontal infection was reignited

in the early 1990s by a series of case-

control and other epidemiologic stud-

ies that demonstrated statistical associ-

ations between poor oral health and

several systemic diseases.


Recent studies have suggested a connectionbetween chronic infections, such as Chlamydiapneumoniae infection or periodontal diseases,and atherosclerosis.27 It has been suggested thatimmunity to bacterial pathogens plays a role inthe atherosclerotic process and that thisresponse may involve autoimmunity.28 It hasbeen observed that almost all humans haveimmune reactions against microbial heat-shockprotein 60 (HSP60). The human version ofthis protein is highly homologous with bacteri-al HSP60. It is possible that the immuneresponse generated against the microbial ver-sion of this protein could cross-react withhuman HSP60 on arterial endothelial cells toinfluence the course of atherosclerosis.28

Bacteria thought to induce gingival inflamma-tion may also stimulate an autoimmuneresponse by presentation of cross-reactive epi-topes that stimulate autoantibody or T-cellresponse reactive with host antigens, such asHSP60, to drive a proinflammatory responsewith cardiovascular effects.29,30

Dental plaque and/or periodontal inflamma-tion may influence pathogenic processes occur-ring in distally contiguous mucosal surfaces, forexample, in the respiratory or digestivetracts.31,32 Salivary hydrolytic enzymes, observedto be elevated in patients with periodontitis,can promote the adhesion of pathogenic bacte-

ria to the oral surfaces, thereby altering oropha-ryngeal colonization patterns. It is also possiblethat periodontopathic bacteria stimulate theperiodontium to release proinflammatorycytokines that, when aspirated or swallowed,alter mucosal surfaces to promote adhesion ofpathogenic bacteria that cause diseases such aspneumonia or gastric ulcers.31,32 Finally, cyto-kines released from inflamed periodontal tissuesmay enter the respiratory tract in aspirated sali-va, triggering the sequence of neutrophilrecruitment, epithelial damage, and infection.31

Gingival Inflammation and Systemic Disease

Several case-control studies33 published inthe early 1990s found that patients with a histo-ry of myocardial infarction had worse oral healththan control subjects (studies are summarized inthe reference). This has led to a flurry of studiesto verify these observations. While most of thesestudies support a modest association betweenperiodontal diseases and the outcomes of ath-erosclerosis (of myocardial infarction, angina, orstroke), several studies have not supported thisassociation. This is complicated by the absenceof a standard definition or measures for peri-odontal diseases and that underlying mecha-nisms common to both periodontal diseases andatherosclerosis share common risk factors, such

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Figure 6—In some subjects, forreasons that remain unknown,the chronic inflammation ofestablished gingivitis spreads toprovoke periodontal ligament andalveolar bone destruction.

21


Bacteria induce platelet aggregate,

invade endothelium, digest matrix

Possible Mechanisms by Which Gingival Inflammation May Modulate Systemic Disease

Gingival Inflammation

Inflammatory mediators (IL-1, IL-6, TNF-α)

Periodontopathogens or their products (LPS)

(C-reactive protein, serum amyloid A, fibrinogen)

Antibodies to bacteria,and to cross-reactive

antigens such as heat-shock proteins;

T-cells sensitized

Periodontopathogens

Immune responseBacteremia

Liver

Target Organ (eg, heart, brain, etc)

Figure 7—Theoretical pathways by which the gingival inflammatory response may impact systemic inflammation and systemicprocesses such as atherosclerosis.

as lifestyle habits like cigarette smoking.How might periodontal inflammation influ-

ence atherosclerosis? It is possible that dentalplaque stimulation of cytokine production inthe periodontium may elevate levels ofcytokines in the peripheral blood. This may inturn stimulate hepatic production of acute-phase proteins, such as CRP. These proteinscould then induce vascular injury, atherogene-sis, cardiovascular disease, and stroke. Severalstudies have shown that patients with peri-odontal diseases demonstrate elevated levels ofCRP and fibrinogen, as well as peripheral whiteblood cells.17,34 Elevated levels of these proteinshave been suggested to be risk factors for car-diovascular disease.35-37 Additional evidence hasbeen reported for the possible direct role of bac-teria in atherosclerosis. It has been reportedthat chronic disease agents, such as C pneumo-niae, play a role in atherosclerotic plaque devel-opment. Recently it has been reported that theDNA of oral bacteria could be amplified direct-ly from atherosclerotic plaques. It is, therefore,possible that these pathogens may play a role in

the development and progression of atheroscle-rosis leading to coronary vascular disease.

Lung diseases such as hospital-acquired pneu-monia and chronic obstructive pulmonary dis-ease (COPD) also have been associated withpoor oral health.31,38 It is possible that oralbiofilms on the teeth may serve as a reservoir ofinfection for respiratory pathogenic bacteria. Insubjects admitted to hospital intensive care unitsor nursing homes, bacteria such as Pseudomonasaeruginosa, Staphylococcus aureus, and entericbacteria have been shown to colonize the teeth.These bacteria may then be released into theoral secretions to be aspirated into the lower air-way to cause infection. It is also possible thatinflammatory mediators, such as cytokines pro-duced by the periodontium, released into thesecretions also can be aspirated to have proin-flammatory effects in the lower airway.

Several epidemiologic studies have reportedassociations between poor oral health andCOPD.39,40 One interesting observation foundthat lung function measured through spirome-try is associated with measures of periodontal

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22


disease.40 In subjects stratified by periodontalattachment loss, those with more severeattachment loss tended to demonstrate lesslung function than those with less attachmentloss. Further research is necessary to dissect the

contribution of periodontal inflammation fromthose of established etiologies, such as smokingon lung function.

There also has been interest in the associa-tion between periodontal inflammation andadverse pregnancy outcomes.41,42 Unfortunately,adverse pregnancy outcomes, such as premature

birth and low birth weight, are quite commonevents. This is a very significant public healthproblem in the United States, and has beenassociated with subclinical genitourinary orother infections. During parturition, the uterusis influenced by the hypothalamus through theproduction of oxytocin, which stimulates uter-ine contraction. Prostaglandins that are pro-duced by the placenta also stimulate uterinecontraction, which normally leads to birth inthe third trimester (37 weeks). It is thought thatchronic infections drive the inflammatoryprocess, which leads to the release of inappro-priate levels of prostaglandins and TNF-α,which prematurely stimulates uterine contrac-tion to promote preterm birth.

It has been suggested that periodontalinfection and the release of lipopolysaccha-rides and other biologically active moleculesdrive the process of inflammation, as describedabove. This results in the elevation ofprostaglandins and TNF-α in the crevicularfluid. Lipopolysaccharides released from theoral cavity into the bloodstream may stimulateprostaglandins in the placenta, causingpreterm birth. It is also possible, such as in ath-erosclerosis, that cytokines in the periodon-tium may lead to elevated peripheral bloodcytokine levels and stimulate hepatic produc-

CE 2

Scientists are beginning to under-

stand the complex molecular

interactions that occur between the

bacteria and salivary pellicle that coats

the tooth, and between gram-positive

cocci of early plaque and gram-negative

filamentous bacteria that populate the

tooth as plaque matures.

23

Metastatic systemic disease: cardiovascular

disease; preterm low birth weight; diabetes; osteoporosis

Health

Dental Plaque

Intervention

Gingivitis

Intervention

PeriodontitisLocal host response: cytokines, antibody

Contiguous systemic disease (sinus disease, lung disease)

Distant host response: liver (acute-phase

response), autoantibody

Figure 8—Suspected interrelationships between gingival inflammation, systemic disease, and response to periodontal therapy.


tion of acute-phase proteins that may influ-ence the birth process. Very recent work hasalso found that periodontal pathogens, such asFusobacterium nucleatum, may travel from thegingival sulcus to the placenta to causepreterm birth.43 Thus, it is possible that thesebacteria may enter the bloodstream from theoral cavity to directly effect the birth process.

SummaryDental plaque drives periodontal inflam-

mation, with gingivitis being the initial mani-festation of this process. With appropriateintervention, this process can be reversed andthe periodontium returned to a state of health(Figure 8). However, an exuberant local hostresponse, including the synthesis of cytokinesand antibodies, in some cases results in thedestruction of periodontal ligament and sup-porting bone (periodontitis). Periodontitis istypically treated by removing the etiology(dental plaque) and returning the gingival tis-sues to health. Unfortunately, in many cases,periodontal disease goes untreated for manyyears. It is possible, then, for the systemic hostresponse to this insult to contribute to diseaseprocesses that result in cardiovascular diseaseand stroke, respiratory disease, and adversepregnancy outcomes.

What is the status of periodontal medicinetoday? While there are a number of prelimi-nary studies that point to an associationbetween periodontal inflammation and severalsystemic conditions, as mentioned above, thedata are equivocal. In many cases, there hasbeen an emphasis on linking periodontalattachment loss with systemic disease. It is pos-sible that the use of this outcome measure,which represents “historical” evidence for thedisease without indicating the temporal seq-uence or duration of disease activity, maycloud the role of periodontal inflammation inthis process. Future investigations are neededthat use better definitions for periodontal dis-ease and measures of how gingival inflamma-tion and tooth loss may best determine the rolethis localized, chronic disease process plays inthe progression and severity of important sys-temic diseases.

References1. Newman HN. Focal infection. J Dent Res. 1996;75:1912-

1919.2. Gibbons RV. Germs, Dr. Billings, and the theory of focal

infection. Clin Infect Dis. 1998;27:627-633.

3. Pallasch TJ, Wahl MJ. The focal infection theory: appraisaland reappraisal. J Calif Dent Assoc. 2000;28:194-200.

4. Kornman KS, Page RC, Tonetti MS. The host response tothe microbial challenge in periodontitis: assembling theplayers. Periodontol 2000. 1997;14:33-53.

5. Graves DT, Cochran D. The contribution of interleukin-1and tumor necrosis factor to periodontal tissue destruction.J Periodontol. 2003;74:391-401.

6. Paster BJ, Boches SK, Galvin JL, et al. Bacterial diversity inhuman subgingival plaque. J Bacteriol. 2001;183:3770-3783.

7. Kinane DF, Lindhe J. Pathogenesis of periodontal disease.In: Lindhe J, ed. Textbook of Periodontology. Copenhagen,Denmark: Munksgaard; 1997.

8. Costerton JW, Stewart PS, Greenberg EP. Bacterial biofilms:a common cause of persistent infections. Science. 1999;284:1318-1322.

9. Kolenbrander PE. Oral microbial communities: biofilms,interactions, and genetic systems. Annu Rev Microbiol. 2000;54:413-437.

10. Armitage GC. Diagnosis of periodontal diseases. J Periodontol. 2003;74:1237-1247.

11. Albandar JM, Kingman A. Gingival recession, gingivalbleeding, and dental calculus in adults 30 years of age andolder in the United States, 1988-1994. J Periodontol.1999;70:30-43.

12. Albandar JM, Brunelle JA, Kingman A. Destructive peri-odontal disease in adults 30 years of age and older in theUnited States, 1988-1994. J Periodontol. 1999;70:13-29.

13. Sbordone L, Bortolaia C. Oral microbial biofilms andplaque-related diseases: microbial communities and theirrole in the shift from oral health to disease. Clin OralInvestig. 2003;7:181-188.

14. Dale BA, Kimball JR, Krisanaprakornkit S, et al. Localizedantimicrobial peptide expression in human gingiva. J Periodontal Res. 2001;36:285-294.

15. Scannapieco FA. Saliva-bacterium interactions in oralmicrobial ecology. Crit Rev Oral Biol Med. 1994;5:203-248.

16. Ebersole JL, Machen RL, Steffen MJ, et al. Systemic acute-phase reactants, C-reactive protein and haptoglobin, inadult periodontitis. Clin Exp Immunol. 1997;107:347-352.

17. Loos BG, Craandijk J, Hoek FJ, et al. Elevation of systemicmarkers related to cardiovascular diseases in the peripheralblood of periodontitis patients. J Periodontol. 2000;71:1528-1534.

18. Danesh J, Collins R, Appleby P, et al. Association of fi-brinogen, C-reactive protein, albumin, or leukocyte countwith coronary heart disease: meta-analyses of prospectivestudies. J Am Med Assoc. 1998;279:1477-1482.

19. Ridker PM, Buring JE, Shih J, et al. Prospective study of C-reactive protein and the risk of future cardiovascular eventsamong apparently healthy women. Circulation. 1998;98:731-733.

20. Löe H, Theilade E, Jensen SB. Experimental gingivitis inman. J Periodontol. 1965;136:177-187.

21. Schenkein HA. Finding genetic risk factors for periodontaldiseases: is the climb worth the view? Periodontol 2000.2002;30:79-90.

22. Silver JG, Martin AW, McBride BC. Experimental transientbacteraemias in human subjects with varying degrees ofplaque accumulation and gingival inflammation. J ClinPeriodontol. 1977;4:92-99.

23. Daly CG, Mitchell DH, Highfield JE, et al. Bacteremia dueto periodontal probing: a clinical and microbiological inves-tigation. J Periodontol. 2001;72:210-214.

24. Ley BE, Linton CJ, Bennett DM, et al. Detection of bacter-aemia in patients with fever and neutropenia using 16SrRNA gene amplification by polymerase chain reaction. EurJ Clin Microbiol Infect Dis. 1998;17:247-253.

25. Kane TD, Alexander JW, Johannigman JA. The detectionof microbial DNA in the blood: a sensitive method for diag-

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nosing bacteremia and/or bacterial translocation in surgicalpatients. Ann Surg. 1998;227:1-9.

26. Meyer MW, Gong K, Herzberg MC. Streptococcus sanguis-induced platelet clotting in rabbits and hemodynamic andcardiopulmonary consequences. Infect Immun. 1998;66:5906-5914.

27. Mosorin M, Surcel HM, Laurila A, et al. Detection ofChlamydia pneumoniae-reactive T lymphocytes in humanatherosclerotic plaques of carotid artery. Arterioscler ThrombVasc Biol. 2000;20:1061-1067.

28. Wick G, Perschinka H, Millonig G. Atherosclerosis as anautoimmune disease: an update. Trends Immunol. 2001;22:665-669.

29. Hinode D, Nakamura R, Grenier D, et al. Cross-reactivity ofspecific antibodies directed to heat shock proteins from peri-odontopathogenic bacteria and of human origin [publishederratum appears in Oral Microbiol Immunol. 1998;13:193].Oral Microbiol Immunol. 1998;13:55-58.

30. Sims TJ, Lernmark A, Mancl LA, et al. Serum IgG to heatshock proteins and Porphyromonas gingivalis antigens in dia-betic patients with periodontitis. J Clin Periodontol.2002;29:551-562.

31. Scannapieco FA. Role of oral bacteria in respiratory infec-tion. J Periodontol. 1999;70:793-802.

32. Umeda M, Kobayashi H, Takeuchi Y, et al. High prevalenceof Helicobacter pylori detected by PCR in the oral cavities ofperiodontitis patients. J Periodontol. 2003;74:129-134.

33. Scannapieco FA, Bush RM, Paju S. Associations betweenperiodontal disease and risk for atherosclerosis, cardiovascu-lar disease and stroke: a systematic review. Ann Periodontol.2003;8:38-53.

34. Noack B, Genco RJ, Trevisan M, et al. Periodontal infec-tions contribute to elevated systemic C-reactive proteinlevel. J Periodontol. 2001;72:1221-1227.

35. Shah SH, Newby LK. C-reactive protein: a novel marker ofcardiovascular risk. Cardiol Rev. 2003;11:169-179.

36. Blake GJ, Ridker PM. Inflammatory bio-markers and car-diovascular risk prediction. J Intern Med. 2002;252:283-294.

37. Hackam DG, Anand SS. Emerging risk factors for athero-sclerotic vascular disease: a critical review of the evidence. J Am Med Assoc. 2003;290:932-940.

38. Scannapieco FA, Bush RM, Paju S. Associations betweenperiodontal disease and risk for nosocomial bacterial pneu-monia and chronic obstructive pulmonary disease: a system-atic review. Ann Periodontol. 2003;8:54-69.

39. Hayes C, Sparrow D, Cohen M, et al. The associationbetween alveolar bone loss and pulmonary function: the VADental Longitudinal Study. Ann Periodontol. 1998;3:257-261.

40. Scannapieco FA, Ho AW. Potential associations betweenchronic respiratory disease and periodontal disease: analysisof National Health and Nutrition Examination Survey III. J Periodontol. 2001;72:50-56.

41. Champagne CM, Madianos PN, Lieff S, et al. Periodontalmedicine: emerging concepts in pregnancy outcomes. J IntAcad Periodontol. 2000;2:9-13.

42. Scannapieco FA, Bush RM, Paju S. Periodontal disease as arisk factor for adverse pregnancy outcomes: a systematicreview. Ann Periodontol. 2003;8:70-78.

43. Han YW, Redline RW, Li M, et al. Fusobacterium nucleatuminduces premature and term stillbirth in pregnant mice:implication of oral bacteria in preterm birth. Infect Immun.2004;72:2272-2279.

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Abstract: Periodontal diseases have long been recognized as a publichealth problem. Awareness of the destructive nature of periodontal dis-eases and the importance of a tight control of bacterial plaque are basicconcepts of periodontal treatment. In the past decade, there has been aconceptual shift from periodontal diseases as an oral problem to peri-odontitis having an impact on systemic health. Recent evidence suggestsa strong relationship between periodontal inflammatory disease and sys-temic diseases, such as cardiovascular disease. It is now generallyaccepted that inflammation plays an important role in atherosclerosis,and factors that systemically amplify inflammation are under close inves-tigation. This article reviews some of the emerging concepts for theinflammatory mechanisms of periodontal diseases and atherosclerosis andexamines the potential role of local inflammation in systemic inflamma-tory disease.

Cardiovascular Diseaseand PeriodontalDiseases: Commonalityand Causation


• describe the majormolecular and cellularmediators of inflamma-tion in periodontal dis-eases and cardiovascu-lar disease.

• list the possible biolog-ic links between peri-odontal diseases andatherosclerosis.

• explain the additionalevidence that will berequired to firmlyestablish a causal linkbetween periodontaldiseases and athero-sclerosis.

• identify risk factorscommon to both peri-odontal diseases andatherosclerosis.

Learning Objectives

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Cardiovascular disease (CVD) accounts for about 50% of deaths in theUnited States each year.1 CVD is characterized by the formation ofintravascular, lipid-rich inflammatory plaques that may give rise to

thromboses and, subsequently, to clinical events such as myocardial infarction(MI).1,2 Currently well-known and well-accepted risk factors for the develop-ment of CVD include smoking, obesity, a high-cholesterol diet, and highblood pressure.1-4 Interestingly, however, only about half of all coronary arterydisease can be explained by these conventional risk factors,5 which suggeststhat other undisclosed factors may be playing a role in atherogenesis.

Earlier attempts to understand the pathogenesis of atherosclerosisfocused on lipid accumulation within the plaque, most notably cholesterolaccumulation.6,7 As scientific understanding of the disease has evolved overthe past several years, it has become apparent that the atheroscleroticplaque, in addition to being an accumulation of lipids, is an inflammatorylesion.8-11 Indeed, recent evidence suggests that in otherwise healthy indi-viduals, markers of systemic inflammation, such as C-reactive protein(CRP), are more predictive of acute coronary events than are low-densitylipoprotein (LDL) levels.12-14 Considering the aforementioned evidence, itseems perfectly reasonable to hypothesize that chronic microbial infectionsmay contribute directly or indirectly to the development of these inflam-matory lesions. This concept has gained greater currency with opinion lead-ers during the past decade as new discoveries in the field have been made.2,9

This has led to a search for possible infectious diseases that may contributeto systemic inflammation and, subsequently, the development of CVD and,specifically, atherosclerosis. It also has led to the hypothesis that atheroscle-rotic lesions are infected lesions and as such may be amenable to antimi-crobial and/or antiviral therapies.15-17 Thus, chronic inflammatory/infectiousdiseases, such as periodontal diseases, have come under closer scrutiny fortheir potential to contribute to both systemic inflammation and bacterial


Sheilesh Dave, DDSClinical Associate

Eraldo L. Batista Jr, DDS, MSc

Research Associate

Thomas E. Van Dyke,DDS, PhD

ProfessorDepartment of Periodontology and

Oral BiologyGoldman School of Dental Medicine

Boston UniversityBoston, Massachusetts


seeding of atherosclerotic plaques.Periodontal diseases are chronic inflammato-

ry diseases of the tissues that support and attachthe teeth to the jaws.18 They are caused bygram-negative bacterial infections and are, forthe most part, asymptomatic, although much ofthe actual destructive tissue changes observedclinically are a result of the inflammatory hostresponse.18 Historically, systemic diseases havebeen considered by the dental profession in thecontext of their influence on the severity ofand predisposition to periodontal disease.19-23

While the importance of periodontal health todental health is not in dispute, its relationshipto systemic disease is beginning to be investi-gated. Areas of ongoing investigation includethe relationship between periodontal diseasesand diabetes mellitus (DM), cerebrovascularischemia, preterm birth, chronic obstructivepulmonary disease, institutional pneumonia,and CVD.24-28 As will be discussed, possible sys-temic links include metastasis of infectioninjury and inflammation.

Cardiovascular DiseaseEarly Inflammatory Events inAtherosclerosis

Early atherogenic events occur in theendothelial cell layer lining the large, elasticarteries. Normally, these cells remain in a “rest-ing” state. When systemic and, later, localinflammatory mediators are released (mostnotably as a result of dietary lipids among otherthings11), endothelial cells undergo importantchanges, which cause them to become “activat-ed.”29 One of the hallmarks of the early athero-sclerotic lesion is the recruitment and adhesionof neutrophils,30 then monocytes and lympho-cytes, to the site of endothelial damage.31 Anumber of surface molecules temporally medi-ate this process, but, especially in the earlystage, the interaction of circulating leukocyteswith the activated endothelial cells seems to bemediated by E- and P-selectins32 and, later, in amore stable fashion, by the intercellular adhe-sion molecule-1 (ICAM-1) and the vascularcell adhesion molecule-1 (VCAM-1).11,33 P-selectins have a broader array of recognizing cellsubsets, binding neutrophils, monocytes, acti-vated lymphocytes, and platelets, acting in con-cert with other molecules expressed in the veryearly stages of atherosclerosis.32 Polymorpho-nuclear (PMN) leukocytes initially “roll” overthe vascular endothelial lining as a result of the

less-than-stable adhesion provided by selectins.Firm adhesion occurs later at the expense ofCD11a/CD18 molecules expressed on PMNand ICAM-1 expressed on endothelial cells. Ithas been shown that adhesion of PMN toendothelial cells pretreated with the cytokinesinterleukin-1 beta (IL-1β) and tumor necrosisfactor-alpha (TNF-α) was substantiallyincreased, also producing a massive increase insuperoxide production by PMN.34 The samestudy also showed that the cytokine-activatedendothelial cells released granulocyte-macro-phage colony-stimulating factor, a powerfulactivator of PMN. PMN’s role during athero-genesis does not seem to be restricted to direct-ly triggering lesion formation by interactingwith the endothelium. Recent evidence showsthat PMN can cause oxidation of LDL by theproduction of myeloperoxidase-mediated acid, apowerful oxidant.35 VCAM-1 seems to be morespecific for monocytes, and has gained particu-lar attention because deficient mice do notdemonstrate normal atherogenic lesion devel-opment with an atherogenic diet.36 VCAMexpressed on endothelial cells is recognized bythe very-late antigen-4 molecule expressed onmonocytes and lymphocytes, allowing these cellsubsets to migrate into the vessel wall. Withinthe intimal layer, leukocytes encounter proin-flammatory molecules, and monocytes presentin this early lesion are then induced to becomemacrophages, which can take up modifiedlipoproteins37 and become lipid-laden “foam-cells.”38 At this point in the pathogenesis, notonly are systemic factors feeding the process, butboth the recruited cells and the endothelialcells sustain the local inflammation by secretingcytokines and chemokines (Table 1),10,39 mostnotably IL-1β, TNF-α, and monocyte chemo-tactic protein-1 (MCP-1). T-cells are stimulatedto produce proinflammatory cytokines, such astumor necrosis factor-beta (TNF-β) and inter-feron gamma (IFN-γ). Along with factorssecreted by the recruited inflammatory cells,other molecules also may contribute to thepathophysiology of atherosclerosis. Forinstance, oxidized LDL has been shown to stim-ulate production of fibroblast growth factor, akey element in fibrotic tissue formation byendothelial cells.39 At this point in lesion devel-opment, the atherosclerotic lesion is a bulge ofthe luminal wall, and as the lesion progresses,the extracellular matrix is degraded by macro-phage-derived proteolytic enzymes.40,41 The

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Table 1—Select Cytokines Related to Pathogenesis of Periodontal Diseases and AtherosclerosisCytokine Main Sources Effects on Periodontium Effects on AtherosclerosisIL-1β Monocytes/macrophages Bone resorption Expression of VCAM-1/ICAM-1/selectins

Fibroblasts Collagen degradation by endothelial cellsEpithelial cells Activation of endothelial cells Attenuation of vasodilationEndothelial cells (ICAM-1/VCAM-1) IL-6 production by monocytesEpicardial adipocytes Enhanced IL-8 production by

gingival fibroblastsExpression of MCP-1 by

gingival fibroblastsTNF-α Monocytes/macrophages Bone resorption Expression of VCAM-1/ICAM-1/selectins

T-cells Collagen degradation Attenuation of vasodilationSMCs Activation of endothelial cells Expression of IL-1/IL-6Myocytes (ICAM-1/VCAM-1) Affects T-cell proliferationEpicardial adipocytes Enhanced IL-8 production by Up-regulates growth factors (PDGF)

gingival fibroblasts Compromises contractile functionExpression of MCP-1 by

gingival fibroblastsIL-6 Monocytes/macrophages Bone resorption (increase in Up-regulation of acute-phase proteins

Endothelial cells osteoclastic activity) (CRP/serum amyloid A)Fibroblasts Late B-cell development Increased procoagulant activity of Epithelial cells monocytesSMCs Stimulation of LDL receptor gene in T-cells hepatocytesEpicardial adipocytesAdipocytes

IL-8 Epithelial cells Recruitment of leukocytes Recruitment of leukocytesEndothelial cellsFibroblastsNeutrophils

MCP-1 Macrophages Recruitment of mono- Recruitment/activation of mono-Endothelial cells cytes/macrophages cytes and macrophagesEpicardial adipocytes Induction of IL-6 production by SMCsFibroblasts

IFN-γ T-lymphocytes Amplification of monocytic ICAM-1 expression of endothelial cellsNatural killer cells respiratory burst activity Proliferation of SMCs

ICAM-1 expression by Decrease in plaque stabilityendothelial cells Increase in LDL uptake by macro-

Down-regulation of IL-8 phages (foam-cell formation)production by gingival Up-regulation of TNF-α expression by fibroblasts monocytes

IL-1β = interleukin-1 beta; TNF-α = tumor necrosis factor-alpha; IL-6 = interleukin-6; IL-8 = interleukin-8; IFN-γ = interferon gamma;SMCs = smooth muscle cells; CRP = C-reactive protein; ICAM-1 = intercellular adhesion molecule-1; VCAM-1 = vascular cell adhe-sion molecule-1; MCP-1 = monocyte chemotactic protein-1; PDGF = platelet-derived growth factor; LDL = low-density lipoprotein.

INF-γ produced by lymphocytes can inhibit col-lagen production by smooth muscle cells,42 thuscausing the fibrous lesion to weaken andbecome susceptible to rupture.43 When theseevents occur, the subendothelial tissue isexposed to procoagulatory factors in the blood-stream, which then may give rise to thrombosesand ensuing clinical events, such as occludedblood flow to the heart or other organs.44 Theconsequence of these events, eventually leading

to acute MI, ultimately depends on a number ofother factors, such as fibrinolytic and coagula-tion factors.1

Classic Inflammatory Agents/Traits and AtherosclerosisOxidation of LDL

Atherosclerosis has long been linked to theconsumption of a fat-rich diet and to increasedlevels of LDL.8 Although it is not proven defin-

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itively, oxidized lipoproteins have been regard-ed as fundamental to the development of ath-erosclerotic disease,45 and the so-called oxida-tion hypothesis is still the most reasonable andacceptable one. According to this theory, LDLis deposited in the intima—possibly throughbinding to proteoglycans—and then undergoesoxidative modifications leading to the forma-tion of carbonyl compounds, lysophospho-lipids, and hydroxyperoxides, among others.3

The influence of oxidized LDL on inflamma-tion is supported by the fact that it seems tomediate monocyte binding to human aorticendothelial cells through the platelet-activat-ing factor receptor.37 In a rabbit model, lipidlowering by means of a controlled diet drasti-cally reduced the macrophage content withinatherosclerotic lesions, as well as proteolyticactivity, which accounts for lesion disruptionand thrombosis.46

Good and Bad Free Radicals,Hypertension and EndothelialDysfunction

Recent evidence points to an important rolefor different reactive oxygen species in thepathogenesis of atherosclerosis.47 Reactive oxy-gen species are generated when electrons areenzymatically transferred to peroxide, produc-ing free, highly reactive radicals such as super-oxide, hydrogen peroxide, and hydroxyl radi-cal. These are capable of causing direct damageto other biological molecules, including pro-teins and cell membrane lipids.48 Not all freeradicals are expected to cause damage; forexample, nitric oxide has been shown to haveanti-inflammatory properties, among them thedown-regulation of VCAM-1.49 Furthermore, ithas been recognized as a key signal-transducingmolecule with important modulating propertieson blood pressure, as it has been shown to reg-ulate vascular tone by inducing vasodilation.50,51

Hypertension has been recognized as a risk fac-tor for atherosclerosis, possibly by inducingendothelial inflammatory responses.52 Hyper-tensive animals have a substantial increase inthe production of superoxide by endothelialcells, suggesting that poor vascular tone controlcould induce changes leading to atherosclero-sis.53 Recently, Cuzzocrea and coworkers54 pro-vided sound evidence that the increased pro-duction of superoxide in hypertensive rats,possibly by endothelial cells, scavenges thenitric oxide necessary to regulate blood pres-

sure. These very results seem to be supported byfindings in human clinical trials where deficitsin endothelial nitric oxide release have beenobserved in coronary and brachial circula-tions.55,56 These findings point to additionalimportant implications in the early inflamma-tory events leading to atherosclerosis; nitricoxide is produced by PMN in response to bac-terial challenge, which suggests that innateimmune response also could affect endothelialfunction. This seems to be supported by a relat-ed finding in rabbits, where PMN productssecreted in response to a diet rich in cholesterolinduced endothelial constriction.57 Additionalevidence demonstrating that neutrophils canmodify LDL by oxidation—thus leading to itsrapid incorporation by macrophages—suggestsa role in the acceleration of atherosclerosis,particularly following cardiac reperfusioninjury.47

DiabetesA link between diabetes and cardiovascular

alterations has been suggested by the inflam-matory trait observed in both diseases.58 Poordiabetic control results in the nonenzymaticglycation and oxidation of proteins, calledadvanced glycation end products (AGE).59

Binding of AGE to its receptor, RAGE, acti-vates endothelial cells to express VCAM-1 andother surface molecules, which take part inlesion formation,60 suggesting an important rolefor poor glucose control in the amplification ofinflammatory events leading to atherosclerosis.

HypertensionThis hypothesis is based on the fact that

angiotensin II can induce intimal inflamma-tion in addition to causing vasoconstriction.Proinflammatory factors that are inducedinclude superoxide anion, MCP-1 and inter-leukin-6 (IL-6) from smooth muscle, andVCAM-1 from the endothelium.61

Markers Associated With IncreasedSystemic Inflammation

Because the atherosclerotic lesion is funda-mentally inflammatory, many efforts havefocused on identifying inflammatory markersthat correlate with disease prognosis. Acutecoronary syndromes (ACS) are positively cor-related with inflammatory mediators, such asCRP, TNF-α, serum amyloid A, IL-1β, and IL-6.12-14 One of the most consistent markers of sys-

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temic inflammation and unfavorable cardiovas-cular prognosis is the acute-phase proteinCRP.12,14 It is produced by hepatocytes andreleased into the circulation, being positivelycorrelated to IL-6.59 CRP activates comple-ment,62 induces expression of adhesion mole-cules,63 induces production of MCP-1 byendothelial cells,64 and accounts for LDLuptake by macrophages.65 More recently, anoth-er putative marker, CD40 ligand, also has beencorrelated with a higher risk of death and recur-rent MI.66,67

Infectious Vectors Associated With Atherosclerosis

The role of infectious elements—bacterialor viral—in the pathogenesis of atherosclerosisis not certain. These elements could directlyamplify the inflammatory response, or theycould act as the sole vector leading to lesionformation. It has been hypothesized that bacte-ria or viruses may directly infect atherosclerot-ic plaques, thus contributing to the observedinflammatory process.68 It has also beenhypothesized that distant infections mayincrease the level of systemic inflammationeither through the release of toxins and by-products or the leakage of inflammatory media-tors into the circulation.68 Epidemiologic and insitu associations between atherosclerosis andcytomegalovirus, Helicobacter pylori, andChlamydia pneumoniae69 have been shown, butcausality has not been convincingly estab-lished.70 Likewise, the presence of infectiouselements in atherosclerotic plaques, includingoral pathogens,71 have been shown but, again,causality has not been established. Neverthe-less, in light of the present knowledge, the con-nection between infections and inflammationleading to atherosclerosis is highly plausible.While a variety of studies have demonstratedpossible molecular mechanisms by which bac-terial infection may exacerbate atherosclerosis,none has been definitively established.

Periodontal DiseasesPeriodontitis is caused by a multifactorial

process triggered by infection of the periodon-tium with gram-negative bacteria. The organ-isms thought to play the most important role inthe pathogenesis of periodontal diseases arePorphyromonas gingivalis, Tannerella forsythensis(formerly designated Bacteroides forsythus), andActinobacillus actinomycetemcomitans.72 In addi-

tion, periodontitis is characterized by the for-mation of a pellicle-adherent, subgingival bac-terial biofilm. Biofilms are defined as matrix-enclosed bacterial populations adherent toeach other and/or to surfaces or interfaces.73

The organisms within the biofilm form a prim-itive yet complex system of communication,intercellular transport, and commensalism.Bacteria within biofilms are often inaccessibleto host defense mechanisms and therapeuticmeasures such as antibiotics. Estimates of thenumber of different organisms that may com-prise this biofilm range as high as 300.72

Although the presence of specific gram-nega-tive bacteria is necessary for periodontal diseaseto occur, it is not sufficient. Indeed, as is wellknown, many individuals who harbor perio-dontopathic organisms do not necessarilydevelop periodontal diseases.74 Thus, host orother unknown factors play a decisive role inthe pathogenesis and progression of periodon-tal diseases. Other important risk factorsinclude, but are not limited to, smoking—forheavy smokers, the odds ratio of developingperiodontal diseases is increased between twoand six times—DM, poor oral hygiene, socio-economic status, and race.18 Thus, many of therisk factors for developing periodontal diseasesalso predispose the individual to developingCVD. Among the virulence factors possessedby periodontal pathogens are the ability toevade host defenses, the ability to attach to andinvade host tissues, and the ability to elaborateenzymes capable of destroying host tissues.72 Forinstance, P gingivalis possesses fimbriae thatallow it to attach to host epithelial andendothelial cells,75 and it produces proteasesthat degrade collagen and other proteases thatdegrade immunoglobulin and complement.76

As mentioned previously, although only arestricted number of organisms have beenthought to play a significant role in the patho-genesis of periodontal diseases, a significantlylarger number of organisms colonize the sub-gingival plaque. These may play a role in thedevelopment of the atherosclerotic lesion asthey gain opportunistic entry to the systemiccirculation through the inflamed periodontalpocket.

Host ResponsesThe response of the host to most periodon-

tal infections is chronic inflammation. Thetooth/periodontium transgingival connection

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constitutes a unique relationship; the root is anavascular mineralized surface, which emergesfrom the bone socket into the mouth, a conta-minated cavity. Separating the “inner” and“outer” environments is the junctional epithe-lium at the base of the gingival sulcus.77 Undernormal conditions, neutrophils continuouslymigrate into the gingival crevicular spacewhere they encounter bacteria and phagocy-tose or otherwise inactivate them.18,78 In addi-tion, immunoglobulin G, nonsecretory immun-oglobulin A, and complement are present inthe gingival crevicular fluid and also participatein the defense against periodontal pathogens.In most individuals, these host defenses,together with adequate oral hygiene, areenough to prevent the development of peri-

odontal disease. If, however, the primary hostresponse is quantitatively or qualitatively insuf-ficient, a biofilm will develop subgingivally. Asthe biofilm persists, it continues to elaboratenoxious substances that both directly and indi-rectly recruit monocytes and lymphocytes tothe periodontium.79 The host attempts to “walloff” the infection by destroying the tissuesimmediately proximal to the site of infectionand, at the same time, inducing a fibroticresponse farther away to prevent the spread ofthe infection.78 This response has both localand systemic inflammatory manifestations.80

Local Inflammatory Manifestations of Periodontal Disease

Once a biofilm has developed in the peri-odontal pocket, it is capable of persisting andthriving there. In addition to harboring poten-tially invasive species, such as P gingivalis and A actinomycetemcomitans, inflammatory sub-stances such as lipopolysaccharides (LPS) andformyl-methionine-leucine-phenylalanine are

continuously being elaborated.81 This causesinflammatory cells and molecules to congregatein the affected periodontal tissues. These medi-ators include molecules such as IL-8 and MCP-1,82 which recruit more neutrophils andmonocytes, respectively. IL-1β and TNF-α,both possessing potent inflammatory effects,also are produced.83 IL-1β is able to stimulateproduction of proinflammatory mediators suchas prostaglandin E2 (PGE2)84 and stimulate theexpression of inflammatory adhesion moleculeson endothelial cells. Interestingly, both IL-1βand TNF-α are expressed at increased levelsduring phases of active periodontal destruc-tion.83 It is possible that these molecules maygain transient access to the systemic circulationduring periods of exacerbation in periodontaldiseases. In addition to the above-mentionedcytokines, IL-2, -4, -5, -6, and -10 also are pro-duced and may play roles in this process.85

These molecules are responsible for regulatingthe activity of T-cells and B-cells. As men-tioned, PGE2 also is produced in response togingival inflammation. Recent evidence sug-gests that host-modulating therapies that, inpart, depress PGE2 production may have anapplication in the treatment of periodontal dis-eases.86 Although in the preliminary stages,these and related investigations being conduct-ed in the authors’ and affiliated laboratorieshave demonstrated that local administration oflipoxin analogs—potent, naturally occurring,anti-inflammatory arachidonic acid deriva-tives—can significantly suppress the progres-sion of periodontal disease in animal models.87

Systemic Markers of Periodontal DiseasePeriodontal diseases are associated with an

increase in CRP levels.88,89 This is significantbecause CRP is a widely accepted measure ofthe level of systemic inflammation, andincreases in CRP levels are associated with anincreased risk of ACS. In patients with bothatherosclerosis and periodontal disease, CRPlevels were elevated above the level seen withonly one disease or the other.90 Periodontal dis-ease also may lead to transient increases in cir-culating levels of IL-1β, TNF-α, and PGE2.This may be the first step in the contribution ofperiodontal diseases to systemic inflammation.

Periodontal Diseases and AtherosclerosisThe recognition of the relationship between

periodontal diseases and atherosclerotic events

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Chronic inflammatory/infectious

diseases, such as periodontal

diseases, have come under closer

scrutiny for their potential to

contribute to both systemic inflamma-

tion and bacterial seeding of athero-

sclerotic plaques.


is relatively recent and mostly based on theinflammatory hypothesis of atherosclerosis,considering that periodontitis is an infection-triggered inflammatory alteration. However,some evidence points to a direct infectious rela-tionship as well. The first associations werebased on epidemiologic data; in a randomizedcontrolled study, Mattila et al91 analyzed 100patients with acute MI and controls from thesame community, correlating dental scores forcarious lesions, missing teeth, periapical lesions,pocket depth (PD) measures, and pericoronitis.Their results showed that overall poor oral/den-tal health correlated positively with coronaryheart disease (CHD) after variables such as age,cholesterol, high-density lipoprotein (HDL),triglycerides, hypertension, diabetes, and smok-ing had been adjusted. A survey involvingNational Health and Nutrition ExaminationSurvey data obtained from nearly 10,000 indi-viduals indicated that those with periodontitishad a 25% increased risk of CHD compared tothose with minimal or no detectable periodon-tal inflammation.92 Importantly, in the latterstudy, confounding variables such as age, gen-der, educational and social status, blood pres-sure, diabetes, and cigarette smoking, amongothers, also were analyzed. In a more directedcase-control approach, it has been pointed outthat atheromatosis and oral infections, age, andtriglycerides were associated.93 To date, no inter-ventional study showing a decreased incidenceof CVD after successful treatment of perio-dontal diseases has been shown, although thiswill be critical to establishing causality.Nevertheless, some evidence emerging fromcontrolled studies begins to establish importantconnections. Different mechanisms have beenproposed to explain the link between oral infec-tions and systemic effects (Figure 1). These aremetastatic spread of infection from the oral cav-ity as a result of transient bacteremia; metastat-ic injury from the effects of circulating oralmicrobial toxins; and systemic inflammationcaused by immunologic injury induced by oralmicroorganisms. This is not to say that a singlemechanism is solely responsible for amplifyingatherogenesis, because most probably they workin concert.

Metastatic InfectionThe incidence of bacteremia, both anaero-

bic and aerobic, after dental procedures such astooth extraction, endodontic treatment, peri-

odontal surgery, and root planing has been welldocumented. In some studies, anaerobes havebeen detected more frequently than facultativeanaerobic bacteria.94-96 If the disseminatedmicroorganisms find favorable conditions, theymay settle at a given site and perhaps prolifer-ate. The DNA of Streptococcus sanguis and theperiodontal pathogen P gingivalis may be ampli-fied from atheromatous plaques.71,97 Thus, theepithelial lining of the periodontal pocket,which frequently becomes thin and even ulcer-ated in disease, may then provide an avenue forsubgingival bacteria periodontally significant(or insignificant) to gain access to the underly-ing host tissue and eventually to the vascula-ture. The fact that P gingivalis is capable ofattaching to and invading both epithelial andendothelial cells75,98 is of particular significancein this regard. Evidence for this derives fromthe high frequency with which bacteremias areobserved in periodontal patients after manipu-lation of periodontal tissues.99-102 A crucialaspect relates to the severity of the periodontaldisease; although not well established, factorsused to determine the severity and risk of peri-odontal disease progression—such as the num-ber of moderate and deep pockets presentingactive inflammation, bone loss, bacterial profil-ing, and antibody titers to periodontal patho-gens—could provide potential indicators ofadditional risk for atherosclerosis.

Metastatic InjurySome gram-positive and -negative bacteria

have the ability to produce diffusible proteins,or exotoxins.103-105 Exotoxins have specific phar-macologic actions and are considered powerfuland lethal poisons. Conversely, endotoxin ispart of the outer membranes released after celldeath. Endotoxin is compositionally an LPSthat, when introduced into the host, gives riseto a large number of pathological manifesta-tions.106 LPS is continuously shed from peri-odontal gram-negative rods during their growthin vivo. Recent evidence that this may be rele-vant comes from Kiechl et al,107 who haveshown that polymorphisms in the toll-likereceptor 4, known to be a key factor in theinflammatory response to certain types of LPS,confer protection against atherosclerosis byattenuating the inflammatory response togram-negative endotoxin.107 Another emergingfeature is the association between antibodies tospecific periodontal pathogens and heart dis-

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ease, suggesting that the host response to oralbacteria plays a role in atherogenesis.108 Aninteresting finding was an inverse correlationbetween antibody response to periodontalpathogens and serum HDL cholesterol, whichimplies reduction in the antiatherogenic prop-erties of HDL.108,109 In another clinical trial, ithas been shown that, along with increased sys-temic inflammation, patients with advancedperiodontal disease present evidence ofendothelial dysfunction.110

Metastatic InflammationAccording to the theory of metastatic

inflammation, inflammatory products resultingfrom oral infection could trigger systemic alter-ation, notably production of acute-phase pro-teins mainly by hepatocytes, such as CRP andserum amyloid A.111 Recently, Li et al112 showedthat P gingivalis, a known periodontal path-ogen, directly inoculated into the tail vein ofmice, caused an acceleration of the atheroscle-rotic process as observed in immunohistochem-istry and histopathology. Another interestingfinding was the fact that IL-1β and serum amy-loid A, an acute-phase protein known to be theanalog of CRP in the mice, was positively cor-related. Jain et al113 observed an increase in the

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Liver

Cytokines

Acute-phase Proteins

PeriodontalDisease

– Biofilm formation– Inflammation

– Attachment loss

BacteriaCirculation

Early Events Atherosclerotic Lesion

PMN

Monocytes

Cytokines LDL

BacteriaMacrophages

Lymphocytes

Cytokines

LDL

Bacteria

Foam-Cells

Figure 1—Proposed connection between periodontal disease and atherosclerosis. Biofilm formation leads to periodontal inflammationand eventual attachment loss. The biofilm covering the avascular root surface “feeds” the local inflammatory process and sustained pro-duction of cytokines by fibroblasts, epithelial cells, and recruited leukocytes and monocytes. Likewise, the biofilm itself may be shearedby physical vectors, causing bacteremia. Both components, bacteria and host products in response to infection, may directly or indirectlycause and/or amplify systemic inflammatory events leading to atherosclerosis. According to the evidence provided thus far, in the earlystages of lesion formation, inflammatory vectors, most notably LDL but also (possibly) circulating cytokines and bacteria, activateendothelial cells lining the arteries, causing them to express surface molecules (please refer to text). These molecules have their counter-receptors on inflammatory cells, which then stably attach to the endothelium. In this very early phase, neutrophils (PMN) initially bind toE- and P-selectins and, later, in a more stable fashion to ICAM via CD11/CD18. Once damage occurs, the endothelium produces chemoat-tractants (IL-8, MCP-1), which recruit more leukocytes and monocytes, thus amplifying the process. Next, monocytes are attracted by theexpression and release of MCP-1, binding to the molecule VCAM-1 expressed on endothelial cells. Once activated, monocytes are con-verted into macrophages, whose expression of scavenger receptors allow them to uptake LDL, becoming in later stages “foam-cells,” ahallmark of atherosclerosis. In later stages, lymphocytes also take part in the pathogenesis of atherosclerosis. Once the inflammatoryprocess is gradually amplified, macrophages start to accumulate in the endothelial layer, forming the atherosclerotic lesion. In later stages(not shown), smooth muscle cells proliferate into the endothelial lesion, leading to the formation of a fibrous cap. Cytokines, specificallyIL-6, induce production of CRP by hepatocytes, which also can amplify systemic inflammation.

33


severity of atherosclerosis in rabbits orally chal-lenged with live P gingivalis on a high-fat diet.Importantly, the severity of the periodontallesions as depicted by bone loss was positivelycorrelated with the extent of the lipid deposi-tion observed in the aorta. Additional recentevidence obtained by a controlled study wasprovided by Lalla et al,114 who showed that oral-ly delivered, P gingivalis–induced periodontalinfections accelerated the development of ath-erosclerotic lesions in heterozygous apolipopro-tein E knockout mice (meaning that apolipo-protein production is suppressed but notcompletely eliminated). A number of studies

have recently pinpointed this relationshipthrough a series of clinical assessments. In thesestudies, strong evidence suggests that periodon-tal infections significantly increase the levels ofCRP.88,89 Supporting these observations, clinicalparameters of periodontitis-like PD and thecommunity periodontal index of treatmentneeds correlated positively with the levels ofLDL and total cholesterol in male patients.115

Controversial Aspects of the LinkBetween Periodontal Diseases andAtherosclerosis

Some evidence to date has shown that thebacterial gene for 16s ribosomal RNA from dif-ferent periodontal pathogens may be amplifiedfrom total DNA extracted from human carotidand aortic lesions.71 This evidence, however,does not pinpoint whether bacteria had, in fact,a key role in the development of the lesion orwhether they are only bystanders in theprocess. It is not clear whether these bacteriastay in the bloodstream long enough to elicitimportant inflammatory changes. Another pos-sible explanation is the continuous expressionof inflammatory mediators within the peri-odontal tissues, which could gain access to thebloodstream and then induce inflammatorychanges on endothelial cells, monocytes, and

macrophages. As mentioned previously, someof the cytokines expressed in the mouth areupstream regulators of the expression of acute-phase proteins by the liver (ie, CRP, serumamyloid A). Evidence to date seems to consis-tently indicate that periodontally diseasedpatients indeed present higher levels of CRP.111

This evidence, however, does not establish acause–effect relationship; most of these studiesrecruited patients with a history of heart dis-ease, and they did not adjust the sample toinclude other important, confounding variablesalso capable of influencing the levels of CRP.The influence of proinflammatory mediatorsexpressed in periodontal diseases and theirinfluence in the levels of systemic markers ofinflammation has yet to be determined.Recently, Glurich et al90 analyzed a number ofdifferent systemic markers in patients witheither periodontal disease or CVD, patientswith both diseases, and healthy subjects.Patients with either periodontal disease aloneor CVD alone had their levels of CRP elevatedtwofold above healthy individuals, whereas athreefold increase was observed in patientswith both alterations; serum amyloid A andalpha (1)-antichymotrypsin also were increasedin comparison to those with one or neithercondition. In seeking a relationship betweensystemic markers of inflammation and peri-odontal disease, the recruitment of patientswith a known history of heart disease may leadto misleading information. This is attributableto the fact that these patients are generallyexposed to other, yet nonamenable, risk factorsthat may account for the levels of systemicmarkers. These include hypertension, high lev-els of LDL, triglycerides, reduced levels ofHDL, and sedentary habits.

ConclusionAs the goal of modern health care continues

to shift from an attitude of treatment to one ofprevention, investigations will increasingly bedirected toward elucidating predisposing fac-tors that lead to atherosclerosis and developingappropriate early intervention. Periodontal dis-eases may represent one such factor. Perio-dontitis itself is endemic in North America andEurope, despite the fact that treatment modali-ties have proven successful over the long termand preventive measures are well understood.Periodontal diseases, like atherosclerosis, are aninflammatory disease. Herein may lie the most

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34

Historically, systemic diseases have

been considered by the dental

profession in the context of their

influence on the severity of and

predisposition to periodontal disease.


plausible link between the two diseases, in thatperiodontal disease may be contributing to aheightened systemic inflammatory state that,in turn, contributes to the progression or exac-erbation of atherosclerosis, although otherexplanations have been put forth. If, as hasbeen suggested in this article, periodontitisconstitutes an independent risk factor for ath-erosclerosis, it will be incumbent on all dentalprofessionals to take appropriate measures toboth counsel patients in the prevention of peri-odontal diseases and, where necessary, arrangetreatment for affected individuals to receiveappropriate care either in a general practice orspecialist setting. Ongoing and future investi-gations in this area will focus on establishingthe molecular basis for the relationshipbetween periodontal diseases and atherosclero-sis, and designing more stringently controlledinterventional studies to establish the presenceof a causal relationship if one indeed does exist.Likewise, development of controlled studies onthe use of additional antimicrobial and anti-inflammatory strategies may provide importantnew tools in the control of atherosclerosis as ahealth problem.

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113. Jain A, Batista EL Jr, Serhan C, et al. Role for periodonti-tis in the progression of lipid deposition in an animalmodel. Infect Immun. 2003;71:6012-6018.

114. Lalla E, Lamster IB, Hofmann MA, et al. Oral infectionwith a periodontal pathogen accelerates early atheroscle-rosis in apolipoprotein e-null mice. Arterioscler ThrombVasc Biol. 2003;23:1405-1411.

115. Katz J, Flugelman MY, Goldberg A, et al. Associationbetween periodontal pockets and elevated cholesterol andlow density lipoprotein cholesterol levels. J Periodontol.2002;73:494-500.

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Abstract: Bacterial plaque has been shown to initiate periodontal dis-eases. Most studies indicate that the host response, rather than thedirect effect of bacteria, is responsible for much of the destruction asso-ciated with periodontitis. Bacteria or their products have an indirect roleby stimulating inflammation, which is associated with the excessive pro-duction of inflammatory mediators, such as prostaglandins, or cytokines,such as tumor necrosis factor-alpha (TNF-α) and interleukin-1. Thesemediators, in turn, induce the production and activation of enzymes thatdestroy gingival connective tissue and stimulate the formation of osteo-clasts to resorb bone. Based on results in animal models and studies inhumans showing that similar responses occur, the initial steps in thebreakdown of connective tissue attachment to the tooth surface and boneresorption involve the production of inflammatory cytokines. Moreover,the risk and severity of periodontal diseases is affected by systemic fac-tors, such as diabetes. Diabetes in particular seems to impair the abilityto produce new bone formation after bone loss by preventing the forma-tion of new bone that normally occurs after bone is resorbed, a processcalled coupling. In addition, the cytokines that stimulate loss of tissue,particularly TNF-α, may kill the cells that repair damaged connectivetissue or bone. In diabetes there may be more TNF-α produced, leadingto an even more limited capacity to repair tissue. The diminished capac-ity to form new bone may make it more difficult for diabetics in particu-lar to repair the loss of tissue that occurs in periodontal diseases.

Evidence that DiabetesMellitus AggravatesPeriodontal Diseases andModifies the Response to an Oral Pathogen in Animal Models


• describe the types ofhost response inducedby bacterial products of plaque, such aslipopolysaccharides.

• explain the role ofcytokines, such asinterleukin-1 andtumor necrosis factor-alpha, on the progres-sion of periodontal disease.

• describe the relation-ship between peri-odontal disease and asystemic disorder suchas diabetes.

• discuss the effect ofdiabetes on boneresorption and boneformation that resultsin a net bone loss.

Learning Objectives

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Acentral question in the pathophysiology of periodontal diseasesconcerns how tissue destruction happens and how systemic condi-tions such as diabetes affect tissue loss. This article is divided into

two parts. The first part addresses the question of how bacterial plaqueleads to tissue destruction in periodontal diseases. The second part discuss-es how a systemic condition, such as diabetes, affects periodontitis. Thisconnection is becoming an increasingly important health issue.

Periodontal DiseasesPeriodontal diseases are a significant cause of tooth loss among adults.

Periodontal diseases are defined as polymicrobial infections that stimulate aninflammatory response in periodontal tissues and result in a loss of support ofthe affected teeth.1 This process is characterized by destruction of the peri-odontal attachment apparatus, loss of crestal alveolar bone, apical migrationof the epithelial attachment, and formation of periodontal pockets.2

It is well understood that periodontal diseases are initiated by plaque that


Dana T. Graves, DDS, DMScProfessor

Hesham Al-Mashat, DDSDSc Candidate

Rongkun Liu, DDS, PhDVisiting Scholar

Department of Periodontology and OralBiology

Goldman School of Dental MedicineBoston University

Boston, Massachusetts


accumulates on the tooth surface. Plaque existsas a complex community of up to hundreds ofdifferent bacterial species that can act coopera-tively. One of dentistry’s important contribu-tions to medical science was to establish thatthere are very significant differences betweenthe behavior of bacteria in a biofilm such asplaque vs the behavior of individual bacteria,which are referred to as “planktonic bacteria.”3

There are different ways that bacteria cancause periodontal destruction, two of whichwill be discussed here. Bacteria can producetoxic compounds and enzymes that can causetissue destruction. Alternatively, bacteria ortheir products may stimulate inflammation thatleads to the activation of host enzymes that areresponsible for tissue destruction.1 An impor-tant issue regarding periodontal diseases iswhich of these mechanisms predominate.

The effect of bacterial plaque on periodon-tal tissue destruction can be evaluated byblocking bacterial growth. This was establishedby demonstrating that antibiotic treatmentimproved periodontal health by removing peri-odontal pathogens.4 However, these studies didnot determine whether bacteria alone or theresultant inflammatory host response to bacte-ria caused the periodontal damage. If bacteriaalone are responsible for most of the tissuedamage, then blocking inflammation wouldhave relatively little effect. If the inflammatoryhost response to bacteria is the more importantcomponent, blocking it would significantlydecrease periodontal disease progression. Thus,blocking the host response represents a key testin determining whether bacteria alone or the

response to bacteria is more crucial in thepathogenesis of periodontal diseases.

Bacterial Plaque and the Inflammatory Host Response

Previously, the host response to a bacterialchallenge was characterized as either acute orchronic inflammation. However, chronicinflammatory diseases, such as periodontitis,have simultaneous acute and chronic compo-nents. As a result, the terms acute or chronicinflammation have been replaced by innate oracquired immune response, respectively.

From an evolutionary standpoint, the innateimmune response developed before the acquiredimmune response. The innate immune responsedepends on pattern recognition and is carriedout by cells such as polymorphonuclear leuko-cytes and monocytes or macrophages. Thesecells have receptors called toll-like receptors,which can discriminate between classes of for-eign molecules. For example, these receptorsrecognize bacterial deoxyribonucleic acid(DNA) but not mammalian DNA, or the bac-terial cell wall component, lipopolysaccharide(LPS) but not mammalian cell walls.5 Thus, anymolecule that binds to these receptors is recog-nized as “foreign” and elicits a host response.This response is characterized by the productionof inflammatory mediators, including cytokines.Cytokines such as interleukin-1 (IL-1) or tumornecrosis factor-alpha (TNF-α) stimulate a num-ber of cellular events, including recruitment ofphagocytic cells to the site of infection which,taken together, represent the innate immuneresponse.

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IL-1 and TNF Blockers Inhibit Osteoclast Formation and Alveolar Bone Loss


The acquired immune response is not basedon pattern recognition but on the very precisebinding of a T-cell receptor to a specific mole-cule. Rather than binding to a class of mole-cules, such as bacterial LPS, which varies con-siderably depending on the bacterium, a givenT-cell receptor in the acquired immuneresponse binds to only a single LPS moleculeproduced by a specific bacterium.6 This allowsprecision in the response, characterized by theformation of antibodies or activation of specif-ic lymphocytes. However, acquired immunityalso is able, under certain circumstances, to rec-ognize self-antigens, allowing development oflethal autoimmune diseases. Because theacquired immune response has the potential tobe very self-destructive, there are elaboratechecks and balances that control its activa-tion.6 As a result of these checks and balances,the acquired immune response takes muchlonger to become fully activated.

Periodontal diseases are difficult to studybecause cause-and-effect relationship studies inhumans cannot be carried out for ethical rea-sons. Thus, animal models are used for this pur-pose. Our laboratory has evaluated both a non-human primate model and a mouse model tostudy host-bacteria interactions relevant to peri-odontal diseases. The primate model sharesmany similarities to human periodontal diseases,including bacterial etiology. In this model, peri-odontal diseases are initiated by tying silk liga-tures containing Porphyromonas gingivalis aroundthe mandibular posterior teeth of Macaca fascic-

ularis monkeys. The ligatures cause plaque accu-mulation and the conversion of gingivitis toperiodontitis.7 More recently, in our laboratoryand others, rodent models are used because thegene sequences of the animals are generallyknown and various reagents are readily avail-able, which facilitates research studies.

Innate Inflammatory Host Response in Experimental Periodontitis

As mentioned, the host response to peri-odontal infection involves both innate andacquired immune responses. To determinewhether the innate immune response con-tributed to periodontal destruction, experimentswere conducted in the nonhuman primatemodel focusing on the cytokines IL-1 and TNF-α.8-10 These molecules are potent stimulatorsinvolved in activating the innate immuneresponse and have been shown to be at higherlevels in individuals with periodontal diseases.11

Although IL-1 and TNF-α levels were shown tobe higher in periodontitis, there was no evidencethat IL-1 or TNF were involved in periodontalbreakdown. To investigate this issue, a controlgroup of nonhuman primates with periodontaldisease was treated only with a placebo (vehi-cle), while an experimental group of animals wastreated with two blocking agents (antagonists).8,9

One of these blockers specifically inhibited IL-1and the other inhibited TNF-α. After 6 weeks,there was a significant loss of bone withincreased numbers of osteoclasts in the controlgroup treated with placebo. When IL-1 andTNF-α were blocked, there was significantly lessbone and fewer osteoclasts (Figure 1). The dataindicate that the presence of IL-1 and TNF-αare important factors in bone loss and that whenthese molecules are inhibited, the amount ofbone loss is considerably reduced.

The effect of inhibiting IL-1 alone also wasdetermined.10 In the animals not treated withblockers, there was a high degree of bone losscompared to the zero time point. This bone losswas significantly reduced by the inhibition of IL-1 (Figure 2). This study indicated that IL-1 wasone of the principal factors in causing bone loss inexperimental periodontitis because the loss wassubstantially reduced when IL-1 was inhibited.

The previous group of experiments demon-strated that IL-1 and TNF-α contributed tobone loss in experimental periodontitis. How-ever, the data did not show whether IL-1 andTNF-α were responsible for the buildup of

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Effect of IL-1 Inhibitor Alone on Alveolar Bone Loss


inflammation close to bone. The study resultsshown in Figure 3 demonstrate that a signifi-cant aspect of periodontitis was caused by therecruitment of inflammatory cells in close prox-imity to bone and that this depended, to a largeextent, on IL-1/TNF-α activity. Under normalconditions, when IL-1 and TNF-α were notinhibited, the conversion from gingivitis toperiodontitis involved the migration of inflam-matory cells deep into the connective tissueclose to bone. The migration of inflammatorycells was largely reduced when IL-1 and TNF-αantagonists were present. It can be concludedfrom this study that the recruitment of theinflammatory white blood cells close to boneinvolved the production of IL-1 and TNF-α,

most likely in response to bacteria that invadedthe gingiva. This conclusion was reachedbecause the IL-1 and TNF-α blockers did notdirectly affect the bacteria but did affect themigration of inflammatory cells close to bone.

Previous studies on blocking prostaglandinsprovided the first indication that inflammationcaused by bacteria resulted in periodontal tissuedestruction.12,13 Prostaglandins are signalingmolecules that are activated as part of the in-nate immune response and are blocked by non-steroidal anti-inflammatory drugs. When theformation of prostaglandins was inhibited,bone resorption in dogs was reduced. If theseresults are combined with our results fromblocking TNF-α and IL-1, a conclusion can be

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Figure 4—P gingivalis was inoculated into the scalp of mice. The number of osteoclasts and amount of bone loss was significantly higher inthe control group than the diabetic group. Diabetic (db/db) and normoglycemic littermate control mice. * indicates significant differencebetween diabetic and normoglycemic mice, P < .05. Adapted from He et al.24

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Osteoclast Formation Induced by P gingivalisIs Less in Diabetic Mice

Recruitment of Inflammatory White Blood Cells Close to Bone Is Reduced at 6 Weeks by IL-1/TNF Blockers

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reached that bacteria-induced inflammation,stimulated and amplified by cytokines andprostaglandins, was responsible for much of thebone loss that occurred with periodontal dis-eases. Thus, one can draw a model in whichbacteria or bacterial products from the gingivalsulcus penetrate the gingiva. If the invasion isdeep enough, inflammation is produced closeto bone that stimulates bone loss. The smalldegree of inflammation initially inducedbecomes amplified because the early signals,such as IL-1 or TNF-α, enhance the productionof later proinflammatory molecules, such asprostaglandins. Both, in turn, can stimulate theformation of osteoclasts and bone resorption.

Gingival connective tissue also can bedestroyed as a result of the release and activa-tion of tissue-degrading enzymes produced dur-ing inflammation. In this case, inflammatorysignals stimulate the production and activationof matrix metalloproteinases that break downcollagen, which is the most important structur-al unit of the gingiva.1,11

Recent data have suggested that the othermajor arm of the immune system, the acquiredimmune response, may also contribute to peri-odontal bone loss.6 Taken together, it appearsthat some, if not much, of the periodontal dam-age that occurs in periodontitis is a result of thehost immune response. (Note: In the authors’studies in monkeys and other studies in dogs, it isclear that modulating the host can prevent themajority of tissue loss. There is little or no evi-dence that bacteria directly cause periodontalbone loss in humans or animals.) Because modu-lation of the host prevented most of the damageobserved, one can conclude that it is the inflam-

mation rather than the direct action of bacteriathat produces this effect. This is consistent withthe idea that periodontal disease is started by bac-teria in plaque, and that these bacteria can pene-trate the gingiva and stimulate inflammation. Byeffective removal of plaque through good oralhygiene and scaling, there is less invasion of theperiodontal tissues by bacteria. With fewer bacte-ria, there is less inflammation and, as a result,reduced periodontal tissue loss. The sequence ofevents also raises the question as to whether itwould be better to turn off the host response topreserve the periodontal tissues. It is the opinionof the authors that the answer to this question isdecidedly no, because significantly compromisingthe inflammatory response has the potential tofacilitate much greater penetration of the gingivaby bacteria with potentially serious systemic con-sequences. This is thought to occur when thehost response is significantly reduced, for exam-ple, in patients with leukocyte adhesion deficien-cy.14 Thus, one can think of periodontal diseasesas localized collateral damage control whicheffectively prevents bacteria that colonize theteeth from penetrating into the gingiva and caus-ing a generalized septic response. However, itmay be possible in the future to fine-tune theinflammatory response so that it is not as destruc-tive to the periodontium.

Diabetes MellitusIt is estimated that 15 million individuals in

the United States have diabetes mellitus.There are two major forms of diabetes. Type 1diabetes, formerly called juvenile diabetes,occurs when the beta cells of the pancreas aredestroyed—usually by autoimmune disease—and insufficient amounts of insulin are pro-duced. Type 2 diabetes occurs when cells areresistant to the action of insulin. Type 2 dia-betes constitutes about 90% to 95% of the dia-betes cases in the United States while most ofthe remainder have type 1 diabetes.15 In type 2diabetic individuals, insulin levels may initiallybe normal or even slightly higher than normal.The principal failure is resistance to insulinstimulation so that glucose transport from thevasculature into cells of the liver and muscle isnot adequately induced. Therefore, glucose lev-els remain high in circulating blood. Type 2diabetes is commonly associated with obesityand, for reasons that are not entirely clear, obe-sity causes cells to not respond well to insulin(ie, to become insulin resistant).15 Studies have

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shown that both types of diabetes increase therisk of periodontal diseases and cause moresevere periodontal breakdown.16-18

The Effect of Diabetes Mellitus on Periodontal Diseases

It has been shown repeatedly that the risk ofperiodontal diseases or periodontal disease pro-gression is greatly influenced by systemic factorssuch as diabetes. Diabetes increases two- to five-fold the likelihood of developing periodontaldiseases.16-18 Treatment of diabetes often reducesthe risk of more severe periodontal disease.19

Because diabetes has a significant impact onbone and periodontal diseases, people with thisdisease need a thorough periodontal evaluationand special consideration in treatment plan-ning. When the diagnosis of periodontal dis-eases is established, active treatment is recom-mended and should be instituted promptly.One consideration, which is currently the sub-ject of considerable research, is that periodon-tal treatment should be carried out becauseuntreated periodontitis may negatively impactsystemic diseases, including diabetes.20 Alongthese lines, it has been reported that effectiveperiodontal treatment helps in the stabilizationof serum glucose levels.20 This may be anotherexample of how a healthy periodontium bene-fits the overall health of the individual by low-ering the probability of systemic inflammationand its consequences.

Several mechanisms have been proposed toexplain the greater incidence and severity ofperiodontal diseases in diabetics. Diabetes tendsto increase susceptibility to bacterial infectionby decreasing the effectiveness of cells that killbacteria.21 Because periodontal diseases are trig-gered by bacteria, a decreased capacity to killbacteria may make it easier for bacteria toinvade the gingiva. Another possibility is thatinflammation tends to be enhanced in thosewith diabetes.22 As a result, diabetes might causethe production of higher levels of proinflamma-tory cytokines, such as IL-1 and TNF-α, there-by leading to greater bone loss.22,23 Thus, both ofthese concepts suggest that there is moreinflammation in those with diabetes, eitherbecause there is a greater tendency of bacteria toinvade the gingiva or more inflammation isstimulated by bacteria that do invade as a resultof the diabetic condition. In both scenarios, agreater degree of inflammation would produceenhanced levels of bone loss. However, this

concept has not been proven conclusively.Another possibility, which has not been inves-tigated, is that diabetes enhances net periodon-tal bone loss because diabetes interferes withthe capacity to form new bone after periodontaldiseases have caused bone resorption.

The Effect of Diabetes Mellitus onBacteria-Stimulated Bone Loss

A dynamic tissue, bone is well adapted forrepair. After bone resorption occurs, growth andremodeling are automatically triggered in aprocess called coupling. However, in periodontaldiseases, there is a net loss of bone so that cou-pling is incomplete. We conducted experimentsto determine whether the principal effect of dia-betes on bacteria-stimulated bone loss wascaused by an increase in bone resorption or adecrease in bone repair after bone loss.Genetically diabetic mice (db/db mice) withtype 2 diabetes and their nondiabetic littermateswere used as a model. The diabetic mice sharedmany similarities to human type 2 diabetes. Ahuman periodontal pathogen, P gingivalis, wasinjected into the connective tissue of the scalpsof both the control and experimental groups ofmice—a method that is useful to study theinflammatory response to oral pathogens and theimpact on bone24,25 because it causes a hostresponse and bone resorption. The bone resorp-tion is then repaired by the formation of newbone. The results of this experiment are shownin Figure 4. Contrary to expectations that dia-betic mice would have enhanced bone resorp-

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tion, we found the opposite. P gingivalis infectioncaused less osteoclast formation and less boneresorption compared to normoglycemic (nondi-abetic) mice. This was surprising because it hasbeen widely held that diabetics have increasedbone resorption after bacterial challenge.

The capacity to repair the resorbed bonewas then measured at the histologic and mole-cular levels. Because bone resorption is fol-lowed by new bone formation, net bone lossoccurs when there is less new bone formed. Inthis study, diabetes had a significant impact onthe capacity to form new bone, thus contribut-ing to net bone lost primarily by diminishingnew bone formation (Figure 5).

To further understand why the diabetic micewere not producing enough new bone, the deathof osteoblasts—the cells that produce new boneafter resorption—was measured. The results indi-cated that there was a much more prolongedhigh rate of osteoblast cell death, also calledapoptosis, in the diabeticgroup (Figure 6). Thus, theincreased death of osteoblastsmay contribute to the dimin-ished capacity of diabeticmice to form new bone afterinfection. To look at thisanother way, whenosteoblasts (the cells that pro-duce bone) die prematurely,the capacity to repair thebone defect by producing newbone is severely limited. Thismeans that the normal cou-pling of bone formation afterresorption does not occur.

DiscussionAlthough bacteria in plaqueare required to initiate theperiodontal disease process,they are not necessarilyresponsible for the resultantactual loss of bone tissue. Theindirect role of bacterialplaque products results in anexcessive production of in-flammatory mediators, such asprostaglandins, or cytokines,such as TNF-α and IL-1,which initiate alveolar boneloss. The severity of perio-dontal diseases also is affectedby systemic factors such as

diabetes mellitus. Diabetes mellitus in particularseems to impair the ability to produce new boneafter bone loss by preventing the normal cou-pling of bone formation and bone resorption.These concepts are described for connective tis-sue in Figure 7A and for bone in Figure 7B. Inconnective tissue bacterial products (such asLPS) stimulate cells (such as macrophages) toproduce IL-1 and TNF-α. IL-1 and TNF-α stim-ulate the production of enzymes that destroy gin-gival connective tissue and may also cause thedeath of fibroblasts that are capable of repairingdamaged tissue. In bone, bacteria or their prod-ucts stimulate nearby macrophages to produceIL-1 or TNF. This stimulates bone lining cellssuch as osteoblasts to produce other factors thatinduce formation of osteoclasts that resorb bone.TNF in particular may also cause cell death ofosteoblasts that repair bone. It is interesting tonote that the initial steps in both gingival con-nective tissue destruction and bone resorption

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Figure 7A—IL-1 and TNF-α can be produced by a number of cells and are able to stimulatemany different biologic activities. IL-1 and TNF-α can stimulate fibroblasts to produce lyticenzymes that can destroy connective tissue matrix. TNF can also cause apoptosis of fibroblasts.

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Figure 7B—IL-1 and TNF-α can stimulate osteoblasts to induce the formation of osteoclaststhat resorb bone matrix. TNF-α can also directly induce fibroblast and osteoblast death.


are thought to be similar. In addition, thesecytokines, particularly TNF-α, may kill the cellsthat repair damaged connective tissue, such asfibroblasts or bone-lining osteoblasts. In diabet-ics, there may be more TNF-α produced, leadingto an even more limited capacity to repair tissue.Moreover, diabetes may also make it more diffi-cult for osteoclasts to form for reasons that areunknown at this time. However, the greatesteffect of diabetes in the mouse model appears tobe on diminished bone formation, which is con-sistent with clinical observation of greater netbone loss in humans with diabetes. This hypoth-esis that bacteria causes enhanced net bone lossin diabetic animals because of an inability toform new bone after resorption was developed ina rodent model and needs to be corroborated inother animal models.

ConclusionSeveral studies have shown that bacterial

plaque initiates periodontal diseases and thattreatment which addresses plaque buildup arethe most reliable approach to treatment. Untilrecently, however, the mechanisms by whichbacteria causes periodontal tissue loss were notwell understood. Studies in nonhuman primatesand in dogs suggest that bacterial invasion of thegingiva stimulates the formation of inflammato-ry mediators such as IL-1, TNF-α, and prosta-glandins, and that inhibition of these mediatorsreduces most of the tissue loss associated withperiodontal diseases. This is consistent withhuman studies showing that these inflammatorymediators are elevated in patients with peri-odontitis. On this basis, it is likely, although notabsolutely proven, that the production of IL-1,TNF, and prostaglandin is a critical step in tissuedestruction associated with various periodontaldiseases. These mediators are also elevated inboth animals and humans who have diabetes.The precise mechanism by which diabetesenhances the risk and severity of periodontal dis-ease is not known. Studies in mice suggest thatdiabetes may reduce the capacity of bone torepair itself after bone resorption. If an individ-ual had bone loss and was able to repair some ofthe lost bone, there would be less net bone lossthan in another individual who had reducedcapacity for repair. The latter may be the case indiabetes. However, many more studies are need-ed to refine this concept and determine whethera similar paradigm exists in other animal modelsand in humans.

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322:373-382.2. Schroeder HE, Listgarten MA. The gingival tissues: the

architecture of periodontal protection. Periodontol 2000.1997;13:91-120.

3. Wilson M. Susceptibility of oral bacterial biofilms to antimi-crobial agents. J Med Microbiol. 1996;44:79-87.

4. Haffajee AD, Socransky SS, Gunsolley JC. Systemic anti-infective periodontal therapy. A systematic review. AnnPeriodontol. 2003;8:115-181.

5. Wang PL, Ohura K. Porphyromonas gingivalis lipopolysaccha-ride signaling in gingival fibroblasts-CD14 and toll-likereceptors. Crit Rev Oral Biol Med. 2002;13:132-142.

6. Teng YT. The role of acquired immunity and periodontal dis-ease progression. Crit Rev Oral Biol Med. 2003;14:237-252.

7. Schou S, Holmstrup P, Kornman KS. Nonhuman primatesused in studies of periodontal disease pathogenesis: a reviewof the literature. J Periodontal. 1993;64:497.

8. Assuma R, Oates T, Cochran D, Amar S, Graves DT. IL-1and TNF antagonists inhibit the inflammatory response andbone loss in experimental periodontitis. J Immunol. 1998 Jan1;160(1):403-409.

9. Graves DT, Delima AJ, Assuma R, et al. Interleukin-1 andtumor necrosis factor antagonists inhibit the progression ofinflammatory cell infiltration toward alveolar bone in exper-imental periodontitis. J Periodontol. 1998;69:1419-1425.

10. Delima AJ, Karatzas S, Amar S, Graves DT. Inflammationand tissue loss caused by periodontal pathogens is reduced byinterleukin-1 antagonists. J Infect Dis. 2002;186:511-516.

11. Offenbacher S. Periodontal diseases: pathogenesis. AnnPeriodontol. 1996;1:821-878.

12. Nyman S, Schroeder HE, Lindhe J. Suppression of inflamma-tion and bone resorption by indomethacin during experimen-tal periodontitis in dogs. J Periodontol. 1979;50:450-461.

13. Williams RC, Jeffcoat MK, Kaplan ML, et al. Flurbiprofen:a potent inhibitor of alveolar bone resorption in beagles.Science. 1985;227:640-642.

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15. Kahn B, Flier J. Obesity and insulin resistance. J Clin Invest.2000;106:473-481.

16. Loe H. Periodontal disease. The sixth complication of dia-betes mellitus. Diabetes Care. 1993;16:329-334.

17. Nishimura F, Takahshi K, Kurihara M, et al. Periodontal dis-ease as a complication of diabetes mellitus. Ann Periodontol.1998;3:20-29.

18. Ryan ME, Carnu A, Kamer A. The influence of diabetes onthe periodontal tissues. J Am Dent Assoc. 2003;134:345-405.

19. Mattson JS, Cerutis DR. Diabetes mellitus: a review of theliterature and dental implications. Compend Contin EducDent. 2001;22:757-760.

20. Mealey DL, Rethman MP. Periodontal disease and diabetesmellitus. Bidirectional relationship. Dent Today. 2003;22:107-113.

21. Mowat A, Baum J. Chemotaxis of polymorphonuclearleukocytes from patients with diabetes mellitus. N Engl JMed. 1971;284:621-627.

22. Salvi GE, Yalda B, Collins JG, et al. Inflammatory mediatorresponse as a potential risk marker for periodontal diseasesin insulin-dependent diabetes mellitus patients. J Periodontol. 1997;68:127-135.

23. Lalla E, Lamster IB, Feit M, et al. Blockade of RAGE sup-presses periodontitis-associated bone loss in diabetic mice. J Clin Invest. 2000;105:1117-1124.

24. He H, Liu R, Desta T, et al. Diabetes causes decreased osteo-clastogenesis, reduced bone formation, and enhanced apop-tosis of osteoblastic cells in bacteria stimulated bone loss.Endocrinology. 2004;145:447-452.

25. Graves DT, Oskoui M, Volejnikova S, et al. Tumor necrosisfactor modulates fibroblast apoptosis, PMN recruitment,and osteoclast formation in response to P. gingivalis infec-tion. J Dent Res. 2001;80:1875-1879.

CE 4

45


Tao Xu, DMD, PhDAssociate Director

Meenal Deshmukh, PhDResearch Scientist

Virginia Monsul Barnes,DDS

Senior Technical Associate

Harsh M. Trivedi, MSTechnical Associate

Diane Cummins, PhDWorldwide Director

The Colgate-Palmolive Company Technology Center

Piscataway, New Jersey

Effectiveness of aTriclosan/CopolymerDentifrice onMicrobiological andInflammatory Parameters


• specify the diseasepathways and conse-quences of periodontaldiseases.

• describe the antibac-terial efficacy of a triclosan/copolymer/fluoride dentifrice,including new molecu-lar techniques availableto document theantibacterial effect.

• discuss the anti-inflam-matory effects of tri-closan, including thespecific markers mea-sured to detect anti-inflammatory efficacy.

Abstract: According to the US Surgeon General’s report, “Oral Healthin America,” published in 2000, most adults in the United States showsome degree of periodontal pathology, with severe periodontal diseasesaffecting about 14% of middle-aged adults. Periodontal diseases arepolymicrobial-induced inflammatory diseases, and they vary from mildgingival inflammation to severe deterioration of the periodontium, ie,loss of periodontal supportive tissues and, ultimately, tooth loss. Newevidence shows that periodontal diseases may impact systemic health.For this reason, the maintenance of a healthy mouth is becomingincreasingly important for the overall health of the body. This articlesummarizes laboratory research conducted during the development of anovel, multibenefit, oral-care technology based on triclosan—a broad-spectrum antibacterial agent—and a polyvinylmethylether/maleic acidcopolymer. This unique combination of agents is found in Colgate®

Total®, a clinically proven efficacious dentifrice for control of dentalplaque and gingivitis. Data are presented that demonstrate the uniqueantibacterial properties of this dentifrice: (1) a broad-spectrum antimi-crobial profile; (2) the long-lasting retention of triclosan on hydroxyap-atite and epithelial cells; and (3) molecular evidence of antibacterialactivity against specific pathogens in clinical dental plaque. In addition,data are presented that demonstrate the anti-inflammatory effects of tri-closan on specific cytokines, the interruption of inflammatory pathways,and the inhibition of bone resorption. Overall, these data support themultibenefit clinical effects of Colgate® Total® and suggest a plurality ofmechanisms of action.

Learning Objectives

Periodontal diseases are polymicrobial diseases, characterized as den-tal-plaque–induced gingival inflammation with loss of periodontalsupport tissues, bone loss, and, ultimately, tooth loss.1-3 For the past

several decades, significant clinical and basic research has established thecomplex pathology of periodontal diseases, and, specifically, that theyinvolve bacterial infection, host immune reaction, and bone metabolism,as well as genetic and environmental risk factors. More recently, a poten-tial link has been identified between periodontal health and systemic dis-eases, including diabetes, cardiovascular disease, respiratory disease, andlow birth weight or preterm birth.

The US Surgeon General’s first-ever “Oral Health in America” reportindicated that most adults in the United States have some degree of peri-odontal pathology, with severe forms of periodontal disease measured as 6 mmof periodontal attachment loss, affecting 14% of adults aged 45 to 55.4 One ofthe major themes of this report was the notion that with increased lifeexpectancy and improved standards of living, oral health means more than


just healthy teeth. Although more research isneeded to substantiate the link between oralhealth and systemic health, the available datahave suggested the importance of oral health tothe control of systemic sequelae.5-9

The importance of bacterial plaque to theonset and progression of periodontal diseases iswell accepted.1-3,10 While more than 400 speciesof bacteria can be detected in the oral cavity,only selective pathogenic species produce prod-ucts harmful to gingival tissues.11,12 The path-way to periodontal destruction is depicted inFigure 1. It shows that dental plaque bacteriainitiate pathogenesis. Microbial products ofspecific pathogens, ie, lipopolysaccharide(LPS) and proteolytic enzymes, directly or indi-rectly trigger a host tissue response by inducingcytokine production and increasing the levelsof inflammatory mediators, leading to inflam-mation and tissue destruction. Without inter-vention or treatment, supporting tissues will bedestroyed, clinical pockets will form, boneresorption will occur, and, ultimately, the toothwill be lost. Potentially more serious than toothloss is the possibility that local oral pathologycould negatively impact the whole body’s

immune response, thereby impacting systemichealth. These concepts and the mechanismsinvolved in periodontal disease etiology havebeen the subject of a number of recent litera-ture reviews.13-18

Given the complexity of periodontal dis-eases and the importance of oral health, one ofthe critical questions is how to best prevent andtreat periodontal infection. Clinical proceduressuch as scaling and root planing provide imme-diate and universal benefits, whereas effectiveroutine oral care can help maintain a healthyoral environment and decrease the occurrenceof oral disease.19

It is interesting to speculate that a combina-tion of antibacterial and anti-inflammatoryefficacy may provide a unique and beneficialapproach to the prevention and treatment ofperiodontal diseases via daily oral-care proce-dures, not only for high-risk individuals, butalso for the general population. Thus, while theprevention and treatment of periodontal dis-eases can be achieved, for the most part,through the control of dental plaque, the con-comitant control of inflammation may addincremental benefit.

A unique triclosan/copolymer/fluoride den-tifrice technology, Colgate® Total®,a, has beendeveloped and clinically proven to enhanceconventional oral-care procedures.20 This tech-nology uses a broad-spectrum antibacterialagent, triclosan, and a polyvinylmethylether/maleic acid (PVM/MA) copolymer to deliversustained antibacterial activity in the oral cav-ity, thereby controlling dental plaque and pre-venting and treating gingival inflammation. Inpractice, this triclosan/copolymer/fluoride den-tifrice has been proven to deliver statisticallysignificant and clinically relevant benefits inthe prevention of caries, the reduction of den-tal calculus buildup and oral malodor, as well asaColgate-Palmolive Company, New York, NY 10022; 800-338-8388

Inflammatory response/ Tissue destruction

Bacterial products (ie, LPS, protease, etc)

Inflammatory mediator/ Cytokine increase

Periodontal pocket/ Bone resorption/Tooth loss and/or Potential impact to systemic health

Oral microbiota/Dental plaque

Figure 1—This illustration of periodontal pathogenesis showswhere bacteria and dental plaque can initiate pathogenesis.Microbial-breakdown products, ie, lipopolysaccharide (LPS) and proteolytic enzymes, can directly or indirectly trigger tissueresponse and inflammatory mediator and cytokine increase,which lead to inflammation and tissue destruction. If the patholo-gy moves forward without intervention, periodontal tissues canbe destroyed, clinical pockets can form, and bone resorption canoccur, leading to possible tooth loss.

Periodontal diseases are polymicro-

bial diseases, characterized as

dental-plaque–induced gingival inflam-

mation with loss of periodontal support

tissues, bone loss, and, ultimately,

tooth loss.

47


the control of dental plaque and treatment ofgingivitis.21 Such a multibenefit oral-care tech-nology can significantly enhance routine oral-care procedures and help to maintain a healthyoral environment.

This article reviews data pertinent to themechanism of action of the triclosan/copoly-mer/fluoride dentifrice and its use in routineoral care for the prevention of plaque and gin-givitis. It is focused primarily on laboratoryresearch into the effects of this dentifrice onoral bacterial pathogens and on triclosan’s roleon host response parameters associated withinflammation.

Antibacterial Efficacy and Control ofDental Plaque

As a broad-spectrum antibacterial agent,triclosan has a nearly three-decade history ofsafe use in soaps and deodorants.17 More than10 years ago, triclosan was successfully intro-duced into oral-care products, specifically den-tifrices and mouthwashes.20 One of the mostsignificant challenges for incorporating the useof triclosan in oral care was to develop a denti-frice formula in which triclosan would be fullycompatible with the excipient ingredients andalso would ensure maximum delivery andretention of triclosan in the oral cavity. Thesolution was to combine triclosan with aPVM/MA copolymer, which stabilizes the tri-

closan in a bioavailable form within the prod-uct matrix, facilitates its release during tooth-brushing, and ensures its adherence in the oralcavity for a prolonged period.

The antibacterial effects of the triclosan/copolymer/fluoride dentifrice on oral organismswere reported by Gaffar et al.22 The authors per-formed the minimum inhibitory concentration(MIC) assay using fresh clinical isolates as wellas standard strains from the American TypeCulture Collection. The MIC values for themajority of the dental plaque pathogens testedwere less than 1 µg/mL (Table 1). In a clinicalstudy,23 dental plaque was collected fromhuman subjects at various time intervals afterthey had brushed with the triclosan/copoly-mer/fluoride dentifrice. The concentration oftriclosan in dental plaque decreased over time,being present at 38.8 ± 18.3 µg/mL and 4.1 ±1.7 µg/mL at 2 and 14 hours, respectively(Table 2). Importantly, the level of triclosanpresent in plaque 14 hours after toothbrushingwas found to exceed the MIC values for most ofthe organisms isolated from dental plaque (asindicated in Table 1). Thus, this triclosan/copolymer/fluoride dentifrice has been found toprovide an effective dose of triclosan to dentalplaque during toothbrushing, where it isretained at antibacterial levels to deliver long-lasting effects for up to 14 hours.

Nabi et al24 published data showing that the

Table 1—Determination of Minimum Inhibitory Concentration of Colgate® Total® on Oral Bacteria*Source of Bacteria Minimum Inhibitory Concentration (MIC in µg/mL)Laboratory strains

MIC values between < 0.38 and 1.14Streptococcus mitis (two species) Fusobacterium nucleatum Actinomyces naeslundii Caphocytophaga ochracea Actinomyces odontolyticus Peptococcus asaccharolyticusPrevotella intermedia

MIC value = 5.35Veillonella parvula

Clinically isolated strainsMIC values between < 0.29 and 0.78Actinobacillus actinomycetemcomitans (two species)Actinomyces odontolyticus (two species)Capnocytophaga spp (two species)Fusobacterium nucleatumActinomyces naeslundii

MIC value = 2.34Capnocytophaga spp 290

*Adapted from Gaffar et al.22

48


presence of 2% PVM/MA copolymer doubledthe amount of triclosan deposited on saliva-coated hydroxyapatite disks (Figure 2). Thismethod mimics the delivery and retention oftriclosan to hard tissues (ie, teeth). In a secondstudy designed to mimic the retention of tri-closan on soft tissues, 2% PVM/MA copolymerwas shown to increase the uptake and retentionof triclosan to exfoliated epithelial cells.25

These results support the clinical observationthat the combination of triclosan and aPVM/MA copolymer delivers a unique, long-lasting antibacterial effect. Furthermore, thisunique effect supports the clinically proven andwell-documented long-term benefits of the tri-closan/copolymer/fluoride dentifrice in regardto dental plaque control, prevention and treat-ment of gingivitis, reduction of dental calculusbuildup and oral malodor, and the preventionof caries.

Molecular Evidence of AntibacterialAction and Long-lasting Benefit

To develop further understanding of theantibacterial effects of this dentifrice, a series ofnew clinical research studies has been conduct-ed using real-time polymerase chain reaction(PCR), a state-of-the-art technique for theanalysis of dental plaque samples. Clinically,the antibacterial effects of oral-care productsare assessed as “gross” effects on plaque accu-mulation by scoring plaque indexes. Thesemeasures do not give any indication of whetherthis antimicrobial activity is directed against

specific microorganisms. Microbiologically,antibacterial effects are measured as reductionsin total bacteria and/or specific species by con-ventional plating and counting-numbers meth-ods. However, it has been increasingly recog-nized that these cultivation techniques areinaccurate, particularly for the study of the eti-ology of periodontal diseases, as many oral bac-teria have very complex physiological require-ments and, thus, cannot be grown and countedin vitro. Furthermore, periodontal pathogensoften constitute only a small fraction of thetotal plaque microbiota, making it difficult tospecifically detect and quantify individualpathogens. On the other hand, PCR-basedassays are capable of detecting the presence orabsence of specific bacteria with much greatersensitivity than cultivable methods. DuringPCR, a single copy of a DNA template isamplified by a factor of a million or more, thus,theoretically, even a single bacterial cell can bedetected. A second advantage of PCR is that itis significantly less labor-intensive than micro-biological culture methods. Real-time PCR

0

10

20

30

40

50

60

0 2

PVM/MA (%, w/v)

Tric

losa

n µg

/Dis

k

Figure 2—Triclosan uptake is increased in the presence of 2% copolymer. Left: the increase of triclosan retention on hydroxyapatitedisks, which mimic the retention to the enamel surfaces. Right: the increase of triclosan retention to the buccal epithelial cells in a cellculture experiment, which simulates triclosan retention to the mucosal surfaces in the mouth. Adapted from Nabi et al.24

0

20

40

60

80

100

0 2

PVM/MA (%, w/v)

Tric

losa

n µg

/10,

000

cells

Increase of Triclosan Retention by the Copolymer

Table 2—Determination of TriclosanConcentration in Clinical Dental Plaque AfterBrushing With Colgate® Total® Toothpaste*

Hours Triclosan (µg/mL)0 02 38.83 ± 18.2814 4.14 ± 1.72

*Adapted from Gaffar et al.23

49


overcomes the limitation of conventionalPCR, which is not quantitative, by allowingquantification of species-specific DNA in agiven sample.26 As there is a direct correlationbetween the number of cells of a specific bacte-rial species and the amount of DNA of thatbacterial species, quantification of DNA is areliable way to estimate the amount of specificbacteria in a mixed microbial population.27

Real-time PCR has been used to detect peri-odontal pathogens in several clinical trials andepidemiologic studies.28,29

In a crossover clinical study, healthy sub-jects were instructed to brush with a standardcommercial fluoride toothpaste and the tri-closan/copolymer/fluoride dentifrice at differ-ent time intervals, with a washout period inbetween. Plaque indexes were recorded andavailable dental plaque was collected from thelingual surfaces before brushing (baseline) and24 hours after brushing (during this time, sub-jects were asked to refrain from any other oralhygiene).30,31 The wet weight of plaque was

recorded and bacterial DNA was isolated fromplaque. A universal primer designed to detectall bacterial DNA and species-specific primerswere made for real-time PCR analysis (Table3). Micrograms of species-specific DNA permilligram of plaque were calculated with theuse of real-time PCR using species-specificprimers to amplify the DNA region encoding16S rRNA. As a part of the bacterial ribosome,the 16S rRNA interacts with specific proteinsand other RNA molecules in the translation ofRNA to protein. The gene coding for 16SrRNA contains highly conserved regions, suit-able for the design of broadly reactive primers,flanking variable and hypervariable regionsthat are used for species identification.28

The effects of the triclosan/copolymer/fluo-ride dentifrice on specific bacterial species wereassessed as a percent reduction or percentincrease by comparing the amounts of species-specific DNA in baseline and 24-hour samples.

Table 3—Oral Bacteria in Clinical Dental Plaque Quantified by Real-time PolymeraseChain Reaction

Total Bacterial Biomass (dental plaque)• Porphyromonas gingivalis• Actinobacillus actinomycetemcomitans• Fusobacterium nucleatum• Bacteroides forsythus• Streptococcus mutans• Actinomyces naeslundii• Lactobacillus caseiThe list represents dental plaque and seven representativeknown oral pathogens selected for DNA quantification by real-time PCR. A universal primer designed to detect all bacterialDNA and species-specific primers were made from the abovebacteria to be used for real-time PCR.

46

29

54

71

0

20

40

60

80

Regular FluorideToothpaste

Colgate® Total®

Increase

Decrease

Perc

enta

ge

Figure 3—Comparison ofreduction of oral pathogens by aunique triclosan/copolymer/fluo-ride dentifrice and a regular fluoride toothpaste. Bars repre-sent percentages of data pointsin which bacterial DNA amountsincreased or decreased 24hours after use of the dentifricerelative to baseline levels. After24 hours, the triclosan/copoly-mer/fluoride dentifrice showed agreater inhibitory effect on oralpathogens (71% of data pointsshowed decreased amounts ofpathogens) compared to regularfluoride toothpaste (54% of datapoints showed decreasedamounts of pathogens).

Comparison of Efficacy Pattern of Colgate® Total®

With a Regular Fluoride Toothpaste on Oral Pathogens via Real-time Polymerase Chain Reaction

50

For the past several decades, signifi-

cant clinical and basic research has

established the complex pathology of

periodontal diseases, and, specifically,

that they involve bacterial infection,

host immune reaction, and bone

metabolism, as well as genetic and

environmental risk factors.


Figure 3 shows the results for five representa-tive subjects for this triclosan/copolymer/fluo-ride dentifrice and the standard fluoride tooth-paste at the 24-hour time point. These dataindicate that the use of the triclosan/copoly-mer/fluoride dentifrice inhibited the regrowthof a higher percentage of oral pathogens thandid the standard fluoride toothpaste.

Further data analysis indicates that specificoral pathogens showed varying levels of suscep-tibility to the use of the standard fluoridetoothpaste. Plaque samples showed significant-ly reduced levels of Lactobacillus casei, a cario-genic microorganism.32 The results suggest thatdaily use of fluoride toothpaste can reduce, aswell as inhibit regrowth of, cariogenic bacteria.Importantly, more significant changes wereobserved 24 hours after the use of the tri-closan/copolymer/fluoride dentifrice, withreductions in bacterial numbers and inhibitionof bacterial regrowth observed for several of theoral pathogens, particularly the periodontalpathogens Fusobacterium nucleatum, Porphyro-monas gingivalis, Actinobacillus actinomycetem-comitans, and Bacteroides forsythus, as well asStreptococcus mutans and Actinomyces naes-lundii. This study provides the first molecularevidence of the antibacterial effects of the tri-closan/copolymer/fluoride dentifrice (Figure 3).The results support the clinically proven bene-fits of this triclosan/copolymer/fluoride denti-frice, namely, the inhibition of dental plaqueand treatment of gingivitis. The data also sug-gest that daily use of this triclosan/copoly-mer/fluoride dentifrice can provide up to 24hours of antibacterial protection and, as aresult, up to 24 hours of dental-plaque control,

which may provide an important contributionto the prevention of oral disease, includingcaries and periodontal inflammation.

Anti-inflammatory Effects of TriclosanInflammation is the body’s self-defense

mechanism to deal with injury and infection.However, excessive or prolonged inflammationcan lead to tissue damage. Prevention and con-trol of inflammation may help to maintainhealthy tissue. With respect to inflammation inthe oral cavity, the prevention and treatment ofgingivitis and periodontitis is beneficial for ahealthy mouth and this, in turn, may be impor-tant for a healthy body. Clinically, the tri-closan/copolymer/fluoride dentifrice treats gin-givitis. Laboratory research suggests that theantigingivitis effect of this triclosan/copoly-mer/fluoride dentifrice results from the com-bined antimicrobial and anti-inflammatoryproperties of triclosan. The antimicrobial activ-ity of triclosan results in better plaque control,while the anti-inflammatory action directlyameliorates the inflammation.22-25,33 Modeer etal33 conducted a series of laboratory studies toassess the anti-inflammatory action of tri-closan. Interleukin-1 beta (IL-1β) is an impor-tant cytokine that can play multiple roles inthe stimulation of the inflammatory response.Specifically, IL-1β can induce prostaglandin E2

(PGE2) production during the process ofinflammation. PGE2 is the most potent stimu-lator of bone resorption and exhibits a broadrange of inflammatory effects. In one study,Modeer et al reported that as IL-1β wasincreased from 50 pg/mL to 200 pg/mL, thepresence of triclosan at 1 µg/mL prevented asignificant increase in PGE2 (Table 4). Tumornecrosis factor-alpha (TNF-α) is also an impor-tant mediator of inflammatory reaction andmay cause tissue damage. In a second study, tri-closan was shown to inhibit TNF-α–inducedPGE2 production. At both 1 and 10 µg/mL

Table 4—Inhibition of PGE2 Production by Triclosan

Inhibition of IL-1β–induced PGE2 production IL-1β (µg/mL) Control Triclosan

(No triclosan) (1 µg/mL) 50 ~10* <1100 ~15 <3200 ~25 ~5Inhibition of TNF-α–induced PGE2 production TNF-α (µg/mL) Control Triclosan

(No triclosan) (1 µg/mL) 1 ~10 <510 ~35 ~10PGE2 = prostaglandin E2; IL-1β = interleukin-1 beta; TNF-α = tumor necrosis factor-alpha.*Values in the columns of control and triclosan represent production of PGE2

picograms per 103 of human gingival fibroblasts. Adapted from Modeer et al.33

Table 5—Comparison of Anti-inflammatoryEffect Between Ibuprofen and Triclosan

PGE2 COX-2Ibuprofen 4.12 1.86Triclosan 13.8 0.59

Stimulation of HEPM Stimulation of RAW cells by IL-1β 10 µg/mL cells by Escherichia

coli LPS at 1 µg/mLPGE2 = prostaglandin E2; COX-2 = cyclooxygenase-2; HEPM = human embryonic palate mesenchymal;LPS = lipopolysaccharide;IL-1β = interleukin-1 beta.

51


TNF-α, PGE2 production was significantlyinhibited by the presence of triclosan (Table 4).It was also found that TNF-α–induced PGE2

production can be inhibited for up to 24 hoursin a human gingival fibroblast cell culture. Thiswas probably because of the inhibition of PGE2

biosynthesis. In addition to its direct effects oncytokines, triclosan can reduce the activity ofthe enzyme cyclooxygenase-2 (COX-2), whichmay also lead to a decrease in the production of

PGE2. Table 5 shows the results of studies thatcompared triclosan in two different cell culturesystems to ibuprofen, a known anti-inflamma-tory drug used as a positive control. Ibuprofenand triclosan both inhibited PGE2 production.However, triclosan was more potent thanibuprofen in inhibiting COX-2. Collectively,the results show that triclosan can inhibitimportant cytokines, PGE2 biosynthesis, andthe COX-2 pathway. Together, these resultssuggest that the anti-inflammatory effects oftriclosan may contribute to the end clinicalbenefit delivered by the triclosan/copolymer/fluoride dentifrice, namely anantigingivitis effect. Finally, in a preliminarylaboratory study, triclosan was found to havethe potential to directly affect bone resorption,a severe downstream consequence of periodon-tal inflammation. Using a parathyroid-hor-mone–induced release of calcium from bonecultures as a model for bone resorption, tri-closan was shown to inhibit PGE2 and calciumrelease.34

SummaryColgate® Total® is a dentifrice containing a

unique active system of triclosan, PVM/MAcopolymer, and sodium fluoride. This combina-tion delivers long-lasting antibacterial andantigingivitis effects for the prevention andcontrol of periodontal inflammation. The labo-ratory data discussed here provides molecular

evidence for the antibacterial effect of this den-tifrice and shows that this effect is efficaciousfor up to 24 hours postbrushing. The data fur-ther confirm and support the long-term anti-plaque and antigingivitis benefits of the tri-closan/copolymer/fluoride dentifrice that havebeen documented in numerous clinical trials.In addition to reducing and inhibiting plaqueand gingivitis, this triclosan/copolymer/fluoridedentifrice delivers complete oral care by pro-viding significant reductions in caries, oral mal-odor, and calculus buildup, and improveswhitening (as measured by the tooth colorshade changes).35 Thus, brushing with the tri-closan/copolymer/fluoride dentifrice con-tributes to the maintenance of a completehealthy oral cavity, and this, in turn, may aid inpromoting the overall health of the body. Asthe US Surgeon General’s report states, oralhealth means much more than healthy teeth;oral health is linked to total health and well-being throughout life. Ignoring oral health canlead to pain and suffering. Therefore, the pre-vention of oral disease via daily oral care mayadd significant positive benefits for long-termtotal health.

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disease. In: Lindhe J, Karring T, Lang NP, eds. ClinicalPeriodontology and Implant Dentistry. 4th ed. Oxford,England: Blackwell Publishing Ltd; 2003:106-149.

2. Newman MG, Takei HH, Carranza FA, eds. Carranza’sClinical Periodontology. 9th ed. Philadelphia, Pa: WBSaunders Company; 2001:96-167.

3. Willmann DE, Harris NO. The role of dental plaque in theetiology and progress of periodontal disease. In: Harris NO,Garcia-Godoy F, eds. Primary Preventive Dentistry. 6th ed.Upper Saddle River, NJ: Pearson Prentice Hall; 2003:73-91.

4. Oral Health in America: A Report of the Surgeon General.Rockville, Md: US Public Health Service, Dept of Healthand Human Services; 2000:1-13.

5. Listgarten MA, Korostoff J. The development and structureof dental plaque (a bacterial biofilm), calculus, and othertooth-adherent organic materials. In: Harris NO, Garcia-Godoy F, eds. Primary Preventive Dentistry. 6th ed. UpperSaddle River, NJ: Pearson Prentice Hall; 2004:23-44.

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7. Genco RJ, Offenbacher S, Beck J. Periodontal disease andcardiovascular disease: epidemiology and possible mecha-nisms. J Am Dent Assoc. 2002;133(suppl):145-225.

8. Offenbacher S, Katz V, Fertik G, et al. Periodontal infectionas a possible risk factor for preterm low birth weight. J Periodontol. 1996;67(10 suppl):1103-1113.

9. Jeffcoat MK, Chestnut CH III. Systemic osteoporosis andoral bone loss: evidence shows increased risk factors. J AmDent Assoc. 1993;124:49-56.

10. Genco RJ, Goldman HM, Cohen DW, eds. ContemporaryPeriodontics. Philadelphia, Pa: The CV Mosby Co; 1990.

Recently, a potential link has been

identified between periodontal

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respiratory disease, and low birth

weight or preterm birth.

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11. Kroes I, Lepp PW, Relman DA. Bacterial diversity withinthe human subgingival crevice. Proc Natl Acad Sci USA.1999;96:14547-14552.

12. Paster BJ, Bosches SK, Galvin JL, et al. Bacterial diversity inhuman subgingival plaque. J Bacteriol. 2001;183:3770-3783.

13. Van Dyke TE, Tohme ZN. Periodontal diagnosis: evaluationof current concepts and future needs. J Int Acad Periodontol.2000;2:71-78.

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15. Lamster IB. Current concepts and future trends for peri-odontal disease and periodontal therapy. Part 1: etiology,risk factors, natural history and systemic implications. DentToday. 2001;20:50-55.

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17. Regos J, Zak O, Solf R, et al. Antimicrobial spectrum of tri-closan, a broad-spectrum antimicrobial agent for topicalapplication. II. Comparison with other antimicrobial agents.Dermatologica. 1979;158:72-79.

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21. Volpe AR, Petrone ME, Prencipe M, et al. The efficacy of adentifrice with caries, plaque, gingivitis, tooth whiteningand oral malodor benefits. J Clin Dent. 2002;13:55-58.

22. Gaffar A, Nabi B, Kashuba B, et al. Antiplaque effects ofdentifrices containing triclosan/copolymer/NaF system ver-sus triclosan dentifrices without the copolymer. Am J Dent.1990;3(spec no):S7-S14.

23. Gaffar A, Afflitto J, Nabi N, et al. Recent advances inplaque, gingivitis, tartar and caries prevention technology.

Int Dent J. 1994;44(suppl 1):63-70.24. Nabi N, Mukerjee C, Schmid R, et al. In vitro and in vivo

studies on triclosan/PVM/MA copolymer NaF combinationas an anti-plaque agent. Am J Dent. 1989;2(spec no):197-206.

25. Volpe AR, Petrone ME, DeVizio W, et al. A review ofplaque, gingivitis, calculus and caries clinical efficacy stud-ies with a dentifrice containing triclosan and PVM/MAcopolymer. J Clin Dent. 1993;4(spec no):31-41.

26. Klein D. Quantification using real-time PCR technology:applications and limitations. Trends Mol Med. 2002;8:257-260.

27. Rupf S, Merte K, Eschrich K. Quantification of bacteria inoral samples by competitive polymerase chain reaction. J Dent Res. 1999;78:850-856.

28. Sakamoto M, Takeuchi Y, Umeda MI, et al. Rapid detectionand quantification of five periodontopathic bacteria by real-time PCR. Microbial Immunol. 2001;45:39-44.

29. Morillo JM, Lau L, Sanz M, et al. Quantitative real-timePCR based on single copy gene sequence for detection ofActinobacillus actinomycetemcomitans and Porphyromonas gin-givalis. J Periodontol Res. 2003;38:518-524.

30. Xu T, Barnes VM. The development of a new dental probeand a new plaque index. J Clin Dent. 2003;14:93-97.

31. Yankell SL, Tawil G, Green PA. Overnight plaque forma-tion. J Prev Dent. 1980;6:313-315.

32. Kleinberg I. A mixed-bacteria ecological approach to under-standing the role of oral bacteria in dental caries causation:an alternative to Streptococcus mutans and specific-plaquehypothesis. Crit Rev Oral Biol Med. 2002;3:108-125.

33. Modeer T, Bengtsson A, Rolla G. Triclosan reducesprostaglandin biosynthesis in human gingival fibroblastschallenged with interleukin-1 in vitro. J Clin Periodontol.1996;23:927-933.

34. Data on file. Piscataway, NJ: Colgate-Palmolive TechnologyCenter.

35. Fischman SL, Yankell SL. Dentifrices, mouthrinses, andchewing gums. In: Harris NO, Garcia-Godoy F, eds. PrimaryPreventive Dentistry. 6th ed. Upper Saddle River, NJ: PearsonPrentice Hall; 2004:119-144.

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Academy of General Dentistry, Approved PACE Program ProviderFAGD/MAGD Credit 7/18/1990 to 12/31/2005

Rationale for the DailyUse of a DentifriceContaining Triclosan in the Maintenance of Oral Health

After reading this article, thereader should be able to:

• discuss why manypatients require a multi-benefit dentifrice as partof their daily oralhygiene regimen.

• list the desirable featuresof a chemotherapeuticantiplaque agent.

• examine the benefitsprovided by a dentifricecontaining triclosan,copolymer, and fluoride.

• describe the role of thecopolymer in thisunique dentifrice.

Abstract: This paper provides an overview and summary of the data thatdemonstrate the effectiveness of a dentifrice containing triclosan/copoly-mer/fluoride in significantly reducing plaque, calculus, gingivitis, andthe onset and progression of periodontitis. The caries-preventive benefitof the triclosan/copolymer/fluoride dentifrice was at least as good as thatof a fluoride dentifrice. No evidence of bacterial resistance or the devel-opment of pathogenic or opportunistic bacteria was observed.

Learning Objectives

Few areas in the human body contain a higher concentration of, ormore diverse, microbiota than the oral cavity. There are more than300 different species of bacteria in the oral cavity, with approximate-

ly 100 billion bacteria per gram of plaque in the gingival sulcus.1,2 It is notsurprising, therefore, that the presence of bacteria in supragingival plaquecan be associated with a variety of oral diseases, including gingivitis.Personal removal of supragingival bacterial plaque (ie, self-performedplaque control) on a daily basis is the most widely accepted method of oraldisease prevention.3 Long-term studies clearly demonstrate that regular,self-performed plaque control, in conjunction with professional, preventivemeasures, is an effective means of maintaining oral health.4,5

The most common method of supragingival plaque control is themechanical removal of plaque through the use of a device such as a tooth-brush.6 A fluoridated dentifrice is often used during the teeth-cleaningprocess, and dental professionals often recommend flossing or some othermeans to improve interdental cleaning. However, such measures are usedless widely and frequently.7,8 Most patients do not brush or floss in the man-ner instructed, or for the amount of time necessary to achieve optimal oralhealth. In one clinical study, the average brushing time for subjects at homewas 37 seconds; and a quarter of the subjects brushed for less than 20 sec-onds.9 While many patients demonstrate improved self-performed plaquecontrol immediately after professional care, in many instances it is only sus-tained for a relatively short period. More evidence to support the theory thatcurrent self-performed oral hygiene practices are not sufficient to maintainan effective level of plaque control and oral health has been reported fromstudies in India, Israel, Scotland, Sweden, and Switzerland.10 For example,although 94% of the subjects reported daily brushing and flossing, all sub-jects had visible plaque on more than 90% of their tooth surfaces.11 Thesestudies and others clearly demonstrate that personal oral hygiene practicesusing mechanical methods of supragingival plaque control are insufficient tomaintain a level of plaque control commensurate with periodontal health.12

Although the success of an individual’s home-care regimen depends onmotivation, dexterity, and compliance, it is unrealistic to assume that most


William DeVizio, DMDWorldwide Director

Clinical Dental ResearchThe Colgate-Palmolive Company

Technology CenterPiscataway, New Jersey

Robin Davies, BDS, PhDDirector

Colgate-Palmolive Dental Health Unit

Manchester, United Kingdom


patients adhere to strict recall schedules andmeticulous daily plaque control.13 Therefore, achemotherapeutic agent can be used to aid thepatient in the mechanical removal of dentalplaque. The desirable characteristics of achemotherapeutic agent that affects dentalplaque are that it should be: nontoxic, nonirri-tating, nonallergenic, safe, effective, pleasanttasting, economical, and easy to use. Ideally,the best delivery mechanism for this effectiveplaque control agent would be a toothpaste.14

Toothpaste is an important mass-consumerproduct that provides a very convenient deliv-ery system. It is widely used and enjoys the sup-port of the dental profession. The dramaticreduction in dental caries in most industrializedcountries since the introduction and wide-spread use of fluoride toothpaste is a testamentto the impact that incorporation of a chemo-therapeutic agent, in this case fluoride, mayhave on oral health.15 The addition of an effec-tive antimicrobial agent to a fluoride-contain-ing dentifrice is appealing because it meetsmany of the criteria of a desirable antiplaqueproduct.

While toothpaste is an ideal vehicle to deliv-er an antiplaque agent, it is very difficult in adentifrice formulation to successfully maintainthe activity and release of the agent whileremaining acceptable to the user.16 One agentthat recently has been successfully incorporatedinto a toothpaste formulation is triclosan.Triclosan is a phenolic agent comprised ofbisphenol and a nonionic germicide. It has lowtoxicity and a broad spectrum of activity.Triclosan is effective against both gram-positiveand gram-negative bacteria. It has been usedsuccessfully in numerous consumer products formore than 30 years. If triclosan is to be used asan antiplaque agent, substantivity—or reten-tion—of the antimicrobial agent to the teethand gingiva is a critical component of efficacy.One toothpaste formulation, Colgate® Total®,a,has successfully improved the substantivity oftriclosan by incorporating a copolymer, poly-

vinylmethylether/maleic acid (PVM/MA). Stu-dies have shown that this combination of tri-closan and PVM/MA copolymer provides long-lasting (up to 12 hours) clinical efficacy.17-19

The clinical efficacy of this triclosan/copolymer/fluoride dentifrice on plaque, and itspositive effects on oral health, has beendemonstrated in approximately 2,000 subjectswho participated in 13 independent, double-blind clinical studies.20 These studies weredesigned in compliance with most regulatoryagencies and professional associations world-wide, including the US Food and DrugAdministration and the American DentalAssociation. From these clinical studies, sub-jects using the triclosan/copolymer/fluoridedentifrice had on average 27% less plaque thansubjects using a fluoride dentifrice. Thisimproved level of plaque control was accompa-nied by a 57% reduction in gingival bleeding.20

It is well known that using dentifrices contain-ing fluoride has resulted in significant reduc-tion in caries.21 It is reasonable to assume that adentifrice containing triclosan and copolymerin addition to fluoride would provide benefitsthat are at least similar. Indeed, 4 studies withapproximately 10,000 participants demonstrat-ed that the triclosan/copolymer dentifrice con-

taining fluoride provided a significant anti-caries benefit that is at least as effective as thatprovided by other dentifrices containing fluo-ride alone.22-25 Several studies also have shownthat the PVM/MA copolymer, in the presenceof triclosan, inhibited crystal growth ofhydroxyapatite,26 which suggested that the den-tifrice might provide an anticalculus benefit.Four clinical studies were conducted on morethan 400 subjects with a history of supragingi-val calculus formation.27-30 It was demonstratedthat the use of a dentifrice containing triclosanand PVM/MA copolymer resulted in a 23% to57% reduction in supragingival calculus whenaThe Colgate-Palmolive Company, New York, NY 10022; 800-338-8388

Few areas in the human body

contain a higher concentration

of, or more diverse, microbiota

than the oral cavity.

There are more than 300 different

species of bacteria in the oral

cavity, with approximately 100 billion

bacteria per gram of plaque in the

gingival sulcus.

55


compared with a fluoride dentifrice, with anaverage reduction of 37%.

In addition to a reduction in dental cariesand calculus formation, the triclosan/copoly-mer/fluoride dentifrice has been shown to beeffective in maintaining gingival health andalso may be beneficial for controlling the onsetand rate of progression of attachment loss inhigh-risk individuals. For example, randomized,controlled studies in adolescents and adultsdemonstrated that the unsupervised use of thetriclosan/copolymer/fluoride dentifrice signifi-cantly reduced the onset and progression ofperiodontitis when compared with a fluoridedentifrice.31-33

While it is highly desirable to use a denti-frice to deliver an effective antimicrobial agent,the benefit to oral health must be balancedagainst potential deleterious shifts in oral ecol-ogy. More specifically, because antibiotic resis-tance may have the potential to become aproblem worldwide, the indiscriminate use ofantimicrobials must be avoided. Therefore, thebenefit-to-risk ratio with regard to use of tri-closan must clearly be favorable for society.

To ascertain the effects of microbial resis-tance to triclosan, clinical studies were con-ducted with a triclosan/copolymer/fluoridedentifrice on more than 1,000 patients overprolonged periods (up to 5 years).34-38 The over-all conclusion from the microbiology studieswas that the use of this triclosan/copolymer/fluoride dentifrice does not cause the develop-ment of pathogenic, opportunistic, or resistantoral microorganisms. These findings corrobo-rate an earlier study conducted on a triclosan/zinc dentifrice.39 Furthermore, these microbiol-ogy studies were reviewed by an expert panel,40

which concluded that:• there is substantial evidence that the use of a

dentifrice containing triclosan and a copoly-mer provides a significant clinical oral healthbenefit in the general population.

• the ultimate indicator of the ability of anantimicrobial agent to induce bacterial resis-

tance in humans can only be determinedfrom clinical studies.

• data from clinical studies of a triclosan/copoly-mer dentifrice up to 1 year in duration clearlyindicate that there is no evidence to supportthe acquisition of bacterial resistance in thesupragingival oral microflora.

• no further studies of the effect on the oralmicroflora of a triclosan/copolymer dentifriceare required to support microbiologic safety.

ConclusionClinical studies clearly indicate that the use

of Colgate® Total® may provide oral health ben-efits beyond those associated with “traditional”toothpaste use, in a manner that is safe andeffective. Dental professionals can confidentlyrecommend this triclosan/copolymer dentifriceto their patients for use as part of their normaloral hygiene regimen.

References1. Haffajee AD, Socransky SS. Microbial etiological agents of

destructive periodontal diseases. Periodontol 2000. 1994;5:78-111.

2. Moore WE, Holdeman LV, Cato EP, et al. Bacteriology ofmoderate (chronic) periodontitis in mature adult humans.Infect Immun. 1983;42:510-515.

3. Hancock EB. Periodontal diseases: prevention. AnnPeriodontol. 1996;1:223-249.

4. Axelsson P, Lindhe J, Nystrom B. On the prevention ofcaries and periodontal disease. Results of a 15-year longitu-dinal study in adults. J Clin Periodontol. 1991;18:182-189.

5. Cutress TW, Powell RN, Kilisimasi S, et al. A 3-year com-munity-based periodontal disease prevention programme foradults in a developing nation. Int Dent J. 1991;41:323-334.

6. Iacono VJ, Aldredge WA, Lucks H, et al. Modern supragin-gival plaque control. Int Dent J. 1998;48(3 suppl 1):290-297.

7. Bakdash B. Current patterns of oral hygiene product use andpractices. Periodontol 2000. 1995;8:11-14.

8. Ciancio SG. Chemical agents: plaque control, calculusreduction and treatment of dentinal hypersensitivity.Periodontol 2000. 1995;8:75-86.

9. Van der Ouderaa FJG, Cummins D. Delivery systems foragents in supra- and subgingival plaque control. J Dent Res.1989;68(spec iss):1617-1624.

10. O’Mullane D. New agents in the chemical control of plaqueand gingivitis: reaction paper. J Dent Res. 1992;71:1455-1456.

11. Christersson LA, Grossi SG, Dunford RG, et al. Dentalplaque and calculus: risk indicators for their formation. J Dent Res. 1992;71:1425-1430.

12. Svatun B, Saxton CA, Huntington E, et al. The effects ofthree silica dentifrices containing triclosan on supragingivalplaque and calculus formation and on gingivitis. Int Dent J. 1993;43(4 suppl 1):441-452.

13. Wilson TG Jr. Compliance and its role in periodontal ther-apy. Periodontol 2000. 1996;12:16-23.

14. Addy M, Renton-Harper P. Local and systemic chemother-apy in the management of periodontal disease: an opinionand review of the concept. J Oral Rehab. 1996;23:219-231.

15. Changing patterns of oral health and implications for oralhealth manpower. Part I. Report of a Working Group con-

Most patients do not brush or

floss in the manner instructed,

or for the amount of time necessary to

achieve optimal oral health.

56


vened jointly by the Federation Dentaire Internationale andthe World Health Organization. Int Dent J. 1985;35:235-251.

16. Cummins D, Creeth JE. Delivery of antiplaque agents fromdentifrices, gels and mouthwashes. J Dent Res. 1992;71:1439-1449.

17. Nabi N, Murkerjee C, Schmid R, et al. In vitro and in vivostudies on triclosan/PVM/MA copolymer/NaF combinationas an anti-plaque agent. Am J Dent. 1989;2(spec no):197-206.

18. Afflitto J, Fakhry-Smith S, Gaffar A. Salivary and plaquetriclosan levels after brushing with a 0.3% triclosan/copoly-mer/NaF dentifrice. Am J Dent. 1989;2(spec no):207-210.

19. Gaffar A, Afflitto J, Nabi N, et al. Recent advances inplaque, gingivitis, tartar and caries prevention technology.Int Dent J. 1994;44(1 suppl 1):63-70.

20. Volpe AR, Petrone ME, DeVizio W, et al. A review ofplaque, gingivitis, calculus and caries clinical studies with afluoride dentifrice containing triclosan and PVM/MAcopolymer. J Clin Dent. 1996;7(suppl):S1-S14.

21. Bratthall D, Hansel-Petersson G, Sundberg H. Reasons forthe caries decline; what do the experts believe? Eur J OralSci. 1996;104(4 pt 2):416-422.

22. Hawley GM, Hamilton FA, Worthington HV, et al. A 30-month study investigating the effect of adding triclosan/copolymer to a fluoride dentifrice. Caries Res. 1995;29:163-167.

23. Feller RP, Kiger RD, Triol CW, et al. Comparison of theclinical anticaries efficacy of an 1100 NaF silica-based den-tifrice containing triclosan and copolymer to an 1100 NaFsilica-based dentifrice without those additional agents: astudy on adults in California. J Clin Dent. 1996;7:85-89.

24. Mann J, Karniel C, Triol CW, et al. Comparison of the clin-ical anticaries efficacy of a 1500 NaF silica-based dentifricecontaining triclosan and a copolymer to a 1500 NaF silica-based dentifrice without those additional agents: a study onadults in Israel. J Clin Dent. 1996;7:90-95.

25. Mann J, Vered Y, Babayof I, et al. The comparative anti-caries efficacy of a dentifrice containing 0.3% triclosan and2.02% copolymer in a 0.243% sodium fluoride/silica baseand a dentifrice containing 0.243% sodium fluoride/silicabase: a two-year coronal caries clinical trial on adults inIsrael. J Clin Dent. 2001;12:71-76.

26. Gaffar A, Esposito A, Afflitto J. In vitro and in vivo anti-calculus effects of a triclosan/copolymer system. Am J Dent.1990;3(spec no):S37-S42.

27. Schiff T, Cohen S, Volpe AR, et al. Effect of two fluoride

dentifrices containing triclosan and a copolymer on calculusformation. Am J Dent. 1990;3(spec no):S43-S45.

28. Lobene R, Battista GW, Petrone DM, et al. Clinical effica-cy of an anticalculus fluoride dentifrice containing triclosanand a copolymer: a 6-month study. Am J Dent. 1991;4:83-85.

29. Volpe AR, Schiff TJ, Cohen S, et al. Clinical comparison ofthe anticalculus efficacy of two dentifrices. J Clin Dent.1992;3:93-95.

30. Banoczy J, Sari K, Schiff T, et al. Anticalculus effect of threedentifrices. Am J Dent. 1995;8:205-208.

31. Ellwood RP, Worthington HV, Blinkhorn AS, et al. Effect ofa triclosan/copolymer dentifrice on the incidence of peri-odontal attachment loss in adolescents. J Clin Periodontol.1998;25:363-367.

32. Rosling B, Wannfors B, Volpe AR, et al. The use of a tri-closan/copolymer dentifrice may retard the progression ofperiodontitis. J Clin Periodontol. 1997;24:873-880.

33. Cullinan MP, Westerman B, Hamlet SM, et al. The effect ofa triclosan-containing dentifrice on the progression of peri-odontal disease in an adult population. J Clin Periodontol.2003;30:414-419.

34. Zambon JJ, Reynolds HS, Dunford RG, et al. Effect of a tri-closan/copolymer/fluoride dentifrice on the oral microflora.Am J Dent. 1990;3(spec no):S27-S34.

35. Bonta CY, Reynolds HS, Dunford RG, et al. Long termeffects of a triclosan/copolymer dentifrice on oral microflo-ra. J Dent Res. 1992;71:577.

36. Walker C, Borden LC, Zambon JJ, et al. The effects of a0.3% triclosan-containing dentifrice on the microbial com-position of supragingival plaque. J Clin Periodontol.1994;21:334-341.

37. Zambon JJ, Reynolds HS, Dunford RG, et al. Microbialalterations in supragingival dental plaque in response to atriclosan-containing dentifrice. Oral Microbiol Immunol.1995;10:247-255.

38. Fine DH, Furang D, Bonta CY, et al. Efficacy of a tri-closan/NaF dentifrice in the control of plaque and gingivitisand concurrent oral microflora monitoring. Am J Dent.1998;11:259-270.

39. Jones CL, Ritchie JA, Marsh PD, et al. The effect of long-term use of a dentifrice containing zinc citrate and a non-ionic agent on the oral flora. J Dent Res. 1988;67:46-50.

40. Seymour G, Cullinan M, Faddy M, et al. Laboratory andclinical evidence documenting the microbiologic safety ofColgate Total. Bio Ther Dent. 2001;16:27-28.

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CE 1—Dr. Mariotti

1. Immediately after cellular injury, whichcells release preformed biochemical mediators?a. stemb. mastc. histamined. B helper cells

2. The complement, clotting, and kinin sys-tems are all tied together through a mixtureof interactions. Which of the following fromone system can activate one or both of theother plasma protein systems?a. mRNAb. proteinc. ribosomed. mitochondria

3. The process in which a cytokine alters the function of adjacent cells is:a. autocrine.b. paracrine.c. found only in dorsal root ganglia.d. found routinely in osteocytes.

4. What are biologically active molecules thatare released into the bloodstream and stimu-late functional activity of cells distant fromthe site of secretion?a. autosomal recessive neutrophilsb. autosomal dominant basophilsc. prokaryoticd. hormones

5. What is the dividing line between acute andchronic inflammation?a. 3 daysb. 7 daysc. 3 monthsd. There is no clear dividing line.

6. The most common systemic effects ofinflammation include fever and:a. leukocytosis.

b. pinocytosis.c. phagocytosis.d. bacterial endocarditis.

CE 2—Dr. Scannapieco

7. Recent work has elucidated complex signaling pathways between bacteria referred to as:a. PCR.b. quorum sensing.c. histopathological balancing.d. ion balance.

8. Periodontitis is associated with extensiveformation of biofilm that is dominated byspirochetes and:a. anaerobic gram-negative bacteria.b. aerobic gram-positive bacteria.c. facultative aerobic bacteria.d. aerobic gram-negative bacteria.

9. The surface area of the periodontal ligamenthas been calculated to cover about:a. 250 square millimeters.b. 250 square centimeters.c. 75 square centimeters.d. 180 square micrometers.

10. Low-grade but persistent bacteremia mayallow oral bacteria to aggregate plateletsthrough:a. protein synthesis.b. receptor-ligand interactions.c. biofilm exudates.d. histamine activation.

11. Recently, it has been reported that DNA oforal bacteria could be amplified directlyfrom:a. gingival fluid.b. oral biofilm.c. parathyroid hormone.d. atherosclerotic plaques.

12. During parturition, the uterus is influenced

QuizDental Learning Systems provides 2 hours of Continuing Education credit for those who wish

to document their continuing education endeavors. Participants are urged to contact their state reg-istry boards for special CE requirements. To receive credit, complete the enclosed answer sheet andmail it, along with a check for $20, to Dental Learning Systems, 405 Glenn Drive, Suite 4, Sterling,VA 20164-4432, for processing. You may also phone your answers in to 888-596-4605, or fax themto 703-404-1801. Participants with a score of at least 70% will receive a certificate documentingcompletion of the course. For more information, call 800-926-7636, ext 180. Program #: D518

58


by the hypothalamus through the produc-tion of:a. prostaglandins.b. oxytocin.c. TNF-α.d. acute-phase proteins.

CE 3—Dr. Dave et al

13. About how much of all coronary artery disease can be explained by conventionalrisk factors?a. one quarterb. halfc. three quartersd. almost all

14. Atherosclerotic plaque, in addition to beingan accumulation of lipids, is a:a. bacterial infection only.b. viral infection only.c. inflammatory lesion.d. completely encapsulated entity.

15. One of the hallmarks of the early athero-sclerotic lesion is the recruitment and adhesion of which of the following to thesite of endothelial damage?a. neutrophilsb. monocytesc. lymphocytesd. all of the above

16. One of the most consistent markers of systemic inflammation and unfavorable cardiovascular prognosis is:a. cytomegalovirus.b. acute-phase protein CRP.c. low-density lipoprotein uptake.d. IL-1β.

17. Separating the “inner” and “outer” environ-ments at the base of the gingival sulcus is the:a. junctional epithelium.b. periodontal ligament.c. remnants of Hertwig’s root sheath.d. epithelial rests of Mallassez.

18. What is a part of the outer membranesreleased after cell death?a. microtoxinb. macrotoxin

c. endotoxind. exotoxin

CE 4—Dr. Graves et al

19. Which of the following represents a key testin determining whether bacteria alone orthe response to bacteria is more crucial inthe pathogenesis of periodontal disease?a. blocking the host responseb. testing of different antibiotic regimens on

agar diffusion platesc. Cochran-Mantel-Haenszel statisticsd. determination of intraluminal vs extralu-

minal bacterial position

20. The term chronic inflammation has beenreplaced by:a. acute inflammation.b. innate immune response.c. acquired immune response.d. cytokine activation phase.

21. The innate immune response depends on:a. T-cell receptor to a specific molecule.b. T-cell receptor to a specific bacteria.c. pattern recognition.d. an autoimmune cascading agent.

22. Previous studies on which of the followingprovided the first indication that inflamma-tion caused by bacteria resulted in periodon-tal tissue destruction?a. migration of IL-1 antagonistsb. blocking prostaglandinsc. buildup of TNF-αd. inhibition of gram-negative cocci

23. After bone resorption occurs, growth andremodeling are automatically triggered in aprocess called:a. osteogenesis.b. phagocytosis.c. diapedesis.d. coupling.

24. A prolonged high rate of osteoblast celldeath is called:a. phagocytosis.b. osteogenesis.c. apoptosis.d. kinincytosis.

59

Gingivitis: An InflammatoryPeriodontal Disease

Proceedings from a Symposium Sponsored by The Colgate-Palmolive Company

This Supplement to The Compendium was sponsored by an unrestricted educational grant from The Colgate-Palmolive Company. To order additional copies, call 800-926-7636, ext. 180. D518

Copyright © 2004. Dental Learning Systems

an inflammatory periodontal disease

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