summary of lecture # 1 september 19, 2007 abdullah s. al-swuailem bds, ms, mph, dr ph

Summary of Lecture Summary of Lecture # # 11

September 19, 2007September 19, 2007

Abdullah S. Al-Swuailem BDS, MS, MPH, Dr PHAbdullah S. Al-Swuailem BDS, MS, MPH, Dr PH

Preventive DentistryPreventive Dentistry

Why Prevention?Why Prevention? Definition of Health. Definition of Health. Types of PreventionTypes of Prevention Remedies if prevention failsRemedies if prevention fails Categories of oral diseasesCategories of oral diseases

Strategies to prevent plaque diseases:Strategies to prevent plaque diseases:

Dental caries and periodontal disease are caused by bacteria and Dental caries and periodontal disease are caused by bacteria and hence are considered infectious diseases. hence are considered infectious diseases.

Virulent bacteria in sufficient number can cause disease in Virulent bacteria in sufficient number can cause disease in susceptible individuals. susceptible individuals.

Dental plaque Composition : Dental plaque Composition : salivary components ( proteins) + bacteria + end products of salivary components ( proteins) + bacteria + end products of

bacterial metabolism . bacterial metabolism .

Primary Prevention in Primary Prevention in Dentistry Dentistry

HostHost BacteriaBacteria

DietDiet

CariesCaries

TimeTime

- Fluoride- Fluoride- Sugar and diet - Sugar and diet - Pit and fissure sealants - Pit and fissure sealants

- Public education- Public education

Primary Prevention in Primary Prevention in Dentistry Dentistry

Read the summary of the Surgeon Read the summary of the Surgeon General Report on “Oral Health in General Report on “Oral Health in America” p-2 in primary Preventive America” p-2 in primary Preventive Dentistry by N. HarrisDentistry by N. Harris

Demineralization and remineralization Demineralization and remineralization phases of dental caries phases of dental caries

Bacterial PlaqueBacterial Plaque

Learning Objectives:Learning Objectives:- Understand the concept of bacterial biofilm in the Understand the concept of bacterial biofilm in the

process of causing diseaseprocess of causing disease- Know and differentiate between subsurface pellicle Know and differentiate between subsurface pellicle

and acquired pellicle and acquired pellicle - Know the stages of dental plaque formation and Know the stages of dental plaque formation and

factors that may affect its build-upfactors that may affect its build-up- Differentiate between sub-gingival and supra-Differentiate between sub-gingival and supra-

gingival calculusgingival calculus


Unlike most diseases, dental caries and Unlike most diseases, dental caries and periodontal disease are caused by a periodontal disease are caused by a variety of bacterial speciesvariety of bacterial species


Microbial biofilm:Microbial biofilm:- All living cells are negatively chargedAll living cells are negatively charged- Biolfim bacteria behave differently from Biolfim bacteria behave differently from

Planktonic (liquid-phase) cells. Bacteria Planktonic (liquid-phase) cells. Bacteria growing in biofilm are more resistant to host growing in biofilm are more resistant to host defence mechanisms and exogenous defence mechanisms and exogenous antimicrobial agents. Thus mechanical antimicrobial agents. Thus mechanical removal of bacterial biofilm is needed to have removal of bacterial biofilm is needed to have effective antimicrobial therapyeffective antimicrobial therapy


- Prior to tooth eruption, microscopic voids on - Prior to tooth eruption, microscopic voids on the enamel surface is filled by organic the enamel surface is filled by organic material of endogenous origin (subsurface material of endogenous origin (subsurface pellicle)pellicle)

- After tooth eruption, a thin coating of salivary - After tooth eruption, a thin coating of salivary film covers the tooth exposed surface and film covers the tooth exposed surface and subsequently become colonized by oral subsequently become colonized by oral bacteria. This exogenous film is called bacteria. This exogenous film is called acquired pellicle acquired pellicle


- If the acquired pellicle is removed it If the acquired pellicle is removed it begins to reform immediately and it begins to reform immediately and it takes about a week for the pellicle to takes about a week for the pellicle to develop its condensed and mature develop its condensed and mature structurestructure

- The acquired pellicle is also formed on The acquired pellicle is also formed on artificial surfaces, e.g. dental artificial surfaces, e.g. dental restorationsrestorations


- The carbohydrate components of The carbohydrate components of certain pellicle glycoproteins may serve certain pellicle glycoproteins may serve as receptors for bacterial-binding as receptors for bacterial-binding protein such as adhesinprotein such as adhesin


Factors influencing the build-up of dental Factors influencing the build-up of dental plaque:plaque:

1.1. Mechanical displacement (chewing, tongue Mechanical displacement (chewing, tongue movement, oral hygiene aids)movement, oral hygiene aids)

2.2. Stagnation (colonization in sheltered Stagnation (colonization in sheltered environments, e.g. inter-proximal area)environments, e.g. inter-proximal area)

3.3. Availability of nutrientsAvailability of nutrients4.4. Interactions between the microbes and the Interactions between the microbes and the

host’s inflammatory immune system host’s inflammatory immune system


Plaque formation:Plaque formation:- Within 2 hours, initial plaque formation begins as a Within 2 hours, initial plaque formation begins as a

series of isolated bacterial colonies confined to tooth series of isolated bacterial colonies confined to tooth surface irregularitiessurface irregularities

- In about 2 days, the plaque double in mass and In about 2 days, the plaque double in mass and bacterial colonies coalesce bacterial colonies coalesce

- In the first 4-5 days of plaque formation, the number In the first 4-5 days of plaque formation, the number of bacteria increase significantlyof bacteria increase significantly

- After approximately 21 days, bacterial replication After approximately 21 days, bacterial replication slows so that plaque accumulation becomes relatively slows so that plaque accumulation becomes relatively stable. Bacteria in the deeper portion of the stable. Bacteria in the deeper portion of the developing plaque are either facultative or obligate developing plaque are either facultative or obligate anaerobesanaerobes


Plaque formation:Plaque formation:- In individuals with poor oral hygiene, superficial dental In individuals with poor oral hygiene, superficial dental

plaque may contain food debris and mammalian cells such plaque may contain food debris and mammalian cells such as desquamated epithelial cells and leukocytes. This debris as desquamated epithelial cells and leukocytes. This debris layer is called materia alba “white matter”layer is called materia alba “white matter”

- First bacteria to adhere to tooth surface are called First bacteria to adhere to tooth surface are called primary colonizers, and are typically non-pathogenicprimary colonizers, and are typically non-pathogenic

- Secondary colonizers bacteria colonize on existing Secondary colonizers bacteria colonize on existing bacterial layerbacterial layer

- Early colonizers are cocci (47-85% streptococci), followed Early colonizers are cocci (47-85% streptococci), followed by short rods and filamentous bacteria. These are mainly by short rods and filamentous bacteria. These are mainly aerobic bacteriaaerobic bacteria

- Sucrose is used to synthesize intracellular and Sucrose is used to synthesize intracellular and extracellular polysaccharidesextracellular polysaccharides


Dental Plaque metabolism:Dental Plaque metabolism:- Upon exposure of dental plaque to sucrose, acid forming Upon exposure of dental plaque to sucrose, acid forming

organism such as S. mutans produce:organism such as S. mutans produce:1.1. AcidsAcids2.2. Intracellular polysaccharidesIntracellular polysaccharides3.3. Extracellular polysaccharides [ glucans (dextran) and Extracellular polysaccharides [ glucans (dextran) and

fructans (levan)]fructans (levan)]- 20% of plaque dry weight is made up of glucans, 10% 20% of plaque dry weight is made up of glucans, 10%

levans, and 70-80% bacterialevans, and 70-80% bacteria- Dental plaque and dental caries and periodontal disease Dental plaque and dental caries and periodontal disease

initiationinitiation


Dental calculus:Dental calculus:- From Latin word meaning stoneFrom Latin word meaning stone- Tartar refers to accumulated sediment or crust on the Tartar refers to accumulated sediment or crust on the

sides of a wine casksides of a wine cask- Calculus in itself is not harmful, but harm comes from Calculus in itself is not harmful, but harm comes from

overlying dental plaqueoverlying dental plaque- Smokers, children with asthma and cystic fibrosis, Smokers, children with asthma and cystic fibrosis,

mentally handicapped individuals, and patients who are mentally handicapped individuals, and patients who are tube-fed over long periods have greater calculus depositstube-fed over long periods have greater calculus deposits

- Patients taking medications such as beta-blockers, Patients taking medications such as beta-blockers, diuretics, and anticholinergics have significantly reduced diuretics, and anticholinergics have significantly reduced levels of calculuslevels of calculus


Dental calculus:Dental calculus:- Supra-gingival calculus: Supra-gingival calculus: - located coronal to gingival margin and frequently located coronal to gingival margin and frequently

develops opposite to duct orifices of major salivary glands. develops opposite to duct orifices of major salivary glands. 30% mineralized. Yellow to white chalky mass30% mineralized. Yellow to white chalky mass

- Sub-gingival calculus:Sub-gingival calculus:- Located below the gingival margin and derived its Located below the gingival margin and derived its

minerals from crevicular fluids within the gingival sulcus. minerals from crevicular fluids within the gingival sulcus. It is thinner and harder (60% mineralized) than supra-It is thinner and harder (60% mineralized) than supra-gingival calculus. Gray to black in color.gingival calculus. Gray to black in color.

- Calculus formation can be inhibited by using agents Calculus formation can be inhibited by using agents containing pyrophosphate or metal ions such as zinc containing pyrophosphate or metal ions such as zinc

summary of lecture # 1 september 19, 2007 abdullah s. al-swuailem bds, ms, mph, dr ph

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