dental plaque 1
TRANSCRIPT
DENTAL PLAQUE
By Dr. Nitika JainPost Graduate Student
DENTAL PAQUE 2
Introduction - distinct habitats of oral cavity Plaque – definition, types. Structure and Composition of Dental Plaque Plaque Formation At Ultra structural Level
Formation of dental pellicle Initial adhesion and Attachment Colonization
Supragingival & Subgingival Plaque Formation: Clinical Aspects
Physiologic Properties of Dental Plaque Plaque As a Bio Film Special Bacterial Behavior In Bio films Plaque hypothesis – specific and non – specific Virulence factors of periodontopathogens Future advances in periodontal microbiology
12/27/2011
DENTAL PAQUE 3
Microbial habitats within the mouth*
On the basis of physical & morphologic criteria, oral cavity can be divided in to 5 major ecosystems:
1. Intraoral, supragingival, hard surfaces (teeth, implants, restorations & prosthesis)
2. Periodontal/periimplant pocket (with its crevicular fluid, root cementum or implant surface, & the pocket epithelium)
3. Buccal epithelium, palatal epithelium & epithelium of floor of mouth.
4. Dorsum of tongue5. Tonsils12/27/2011
DENTAL PAQUE 4
Distribution of Resident Oral Micro flora
Teeth •Non shredding surfaces• Stagnant sites; food
impaction possible• Influenced by GCF &
saliva• Streptococcus,
Actinomyces, Veillonella, Fusobacteria, Prevotella, Treponema, unculturable
organisms
Tongue• Highly papillated surfaces• Some anaerobic sites.
• Facultative & obligate anaerobes• Diverse microflora Streptococcus,
Actinomyces, Rothia, Neisseria
Cheeks, Lips, Palate• Microflora has low
diversity• Some periodontal pathogens persist by invading buccal
cells.•Streptococcus spp.
predominate
12/27/2011
DENTAL PAQUE 5
Principal Bacterial Genera Found In Oral Cavity
Gram negative
cocci
rods
Gram positive
cocci
rods12/27/2011
DENTAL PAQUE 6
Gram PositiveCocci Rods
Abiotrophia Actinobaculum
Enterococcus Actinomyces
Gemella Alloscardovia
Preptostreptococcus Bifidobacterium
Streptococcus Cornybacterium
Finegoldia Eubacterium
Granulicatella Filifactor
Lactobacillus
Propionibacterium
Rothia
solobacterium12/27/2011
DENTAL PAQUE 7
Gram Negative
Cocci Rods
Anaeroglobu Aggregatibacter
Mega sphaera Campylobacter
Moraxella Cantonella
Neisseria Capnocytophaga
Veillonella Centipeda
Eikenella
Leptotrichia
Prevotella
Porphyromonas
Tanerella
Treponema
wolinella
12/27/2011
DENTAL PAQUE 8
Bacterial Composition of Dental Plaque From Different Sites
Tooth
Approximal • Gram positive
& gram negative;
facultative & obligate
anaerobes:1. Neisseria
2. Streptococcus
3. Prevotella4. Actinomyces
5. veillonella
Gingival crevice• Gram positive
& gram negative &
obligate anaerobes:
1. Streptococcus
2. Prevotella3. Actinomyces4. Treponema
5. Eubacterium
Fissure• Gram positive;• Facultative
anaerobes 1. Streptococcu
s2. Actinomyces
12/27/2011
DENTAL PLAQUEDefinitions
DENTAL PAQUE 10
Definations Dental plaque is defined clinically as a
structured, resilient, yellow-grayish substance that adheres tenaciously to intraoral hard surfaces, including removable or fixed restorations.
“Bowen WH: Nature of plaque, Oral science review 1976”
Dental plaque is a general term for complex microbial community that develops on the tooth surface, embedded in a matrix of polymers of bacterial & salivary origin.
“Philip D Marsh, Michael V Martin, Oral Microbiology, 5th Edition.”
12/27/2011
DENTAL PAQUE 11
Dental plaque can be defined as the soft deposits that form the biofilm adhering to the tooth surface or other hard surfaces in the oral cavity, including removable and fixed restorations.
Carranza 9th edition
12/27/2011
DENTAL PAQUE 12
1880 1900 1930 1960 1990 2000
Sp pathogens identified for many diseases Search begins for oral pathogens in plaque
Non sp plaque HypothesisDiseases linked to constitutional defects
Sp plaque hypothesisTreatment aimed atCausative agent
Biofilm
Golden age ofmicrobiology
Plaque controlBiofilm
CHANGING VIEWS OF PLAQUE
12/27/2011
DENTAL PAQUE 13
Classification of dental plaque – Listgarten (1976) Classified Dental Plaque According to its Location as
Marginal plaque*
Supra gingival*
Sub gingival*
• Tooth associated
• Tissue associated
12/27/2011
DENTAL PAQUE 1412/27/2011
DENTAL PAQUE 15
Dental plaque must be differentiated from other tooth deposits, like materia alba and calculus.
Materia Alba refers to soft accumulations of bacteria and tissue cells that lack the organized structure of dental plaque.
Calculus is hard deposits that form by mineralization of dental plaque and is generally covered by a layer of un mineralised plaque.
12/27/2011
DENTAL PAQUE 16
Material alba Calculus
12/27/2011
DENTAL PAQUE 17Carranza 11th edition
12/27/2011
DENTAL PAQUE 18
Plaque can be defined as a complex microbial community, with greater than 1010 bacteria per milligram. Socransky SS et al “The micro biota of gingival crevice
area of man” JCP 25:134, 1998
In addition to the bacterial cells, plaque contains a small number of epithelial cells, leukocytes, and macrophages. The cells are contained within an extracellular matrix, which is formed from bacterial products and saliva.
The extracellular matrix contains protein, polysaccharide, lipids and glycoproteins.
12/27/2011
DENTAL PAQUE 19
DENTAL PLAQUE
12/27/2011
Composition – organic and in - organic
DENTAL PAQUE 20
CHEMICAL COMPOSITION OF DENTAL PLAQUE
80% water 20% solids, includes cells mainly bacteria making up 35%
of the dry weight and extracellular components making 65% of the dry weight.
Other than bacteria, non bacterial organisms include:• Mycoplasma• Yeast• Protozoa• Viruses
Host cells in Dental plaque. Epithelial cells Macrophages Leukocytes
12/27/2011
DENTAL PAQUE 21
INTERCELLULAR MATRIX OF DENTAL PLAQUE
Organic constituents
Inorganic constituents
Material from Saliva, GCF and bacteria
12/27/2011
DENTAL PAQUE 22
ORGANIC CONSTITUENTS
Poly saccharides - dextran 95% (adhesion), levan 5%, Sialic acid and fructose
Proteins - Albumin
Glycoproteins - saliva
Lipid materials - Membrane remnants of bacteria and host cells.
12/27/2011
DENTAL PAQUE 23
INORGANIC CONSTITUENTS
Primarily - Calcium & Phosphate
Traces - Sodium, Potassium and Fluoride
Fluoride - From external sources likeis derived tooth paste, mouth washes
12/27/2011
DENTAL PAQUE 24
DENTAL PLAQUE
12/27/2011
Formation
DENTAL PAQUE 25
DEVELOPMENT OF DENTAL PLAQUE
The formation of the pellicle on the tooth
surface
Initial adhesion and attachment of bacteria
Colonization and plaque maturation
12/27/2011
DENTAL PAQUE 26
Formation of the pellicle
Within nanoseconds after a vigorously polishing the teeth, a thin, saliva derived layer called the acquired pellicle, covers the tooth surface.
Consists of more than 180 peptides, proteins, glyco proteins, including keratins, mucins, proline – rich proteins, and other molecules can function as adhesion sites( receptors) for bacteria.
12/27/2011
DENTAL PAQUE 27
ULTRA STRUCTURE OF DENTAL PELLICLE
Thickness - 30 - 100 nm
2 hr pellicle: Granular structures which form
globules, that connect to the Hydroxyapatite
surface via stalk like structures.
24 hrs Later: Globular structures get covered up
by fibrillar particles : 500 - 900 nm thick
36 hrs Later: The pellicle becomes smooth,
globular
12/27/2011
DENTAL PAQUE 28
Studies shows ( 2 hours) enamel pellicle, its amino acids composition differs from that of saliva, indicating that the pellicle forms by selective adsorption* of the environmental macromolecules.
Scannapieo FA et al , “ saliva and dental pellicles’” contemporary periodontics, 1990
Mechanism involved are:Electrostatic forces *Van der waals *Hydrophobic forces*
12/27/2011
DENTAL PAQUE 2912/27/2011
DENTAL PAQUE 30
CHEMICAL COMPOSITION OF ACQUIRED PELLICLE (Mayhell & Butller 1976, Sonju 1975)
4.6% amino acids 2.7% Hexosamine 14% Total carbohydrates Lipids - in small amounts
Amino acids in the pellicle Pellicle contains more hydrophobic and less neutral amino acids than whole saliva (ie more leucine, alamine, tyrosine and sereine than saliva)
Hexosamines in the pellicle Glucosamine - 18%, Galactosamine -18%
Carbohydrates in the pellicle Glucose - 20%, Galactose - 27%Mannose - 9% Fructose - 18%
Salivary Molecules in the pellicle Acinar cell familiesMucins
Proline rich proteins - statherins
Cystatins, Amylases
Ductal & stromal products
Lactoferrin & Lysozyme
12/27/2011
DENTAL PAQUE 31
Initial Adhesion & Attachment of Bacteria
This concept approaches microbial adhesion to surfaces in aquatic environment as 4 stage sequence:
Transport to surface
Initial adhesion
Attachment
Colonization of surface & biofilm formation
12/27/2011
DENTAL PAQUE 32
Clean substratum
Molecular adsorption(Phase 1)
Single organisms (Phase 2)
Multiplication (Phase 3)
Sequential adsorptionof organisms(Phase 4)
12/27/2011
DENTAL PAQUE 33
Transport to the surface
Random contacts occur through:
Brownian motion ( 40 µm/hour)* Sedimentation of organisms* Liquid flow Active bacterial movement (chemotactic
activity)*
12/27/2011
DENTAL PAQUE 34
Initial adhesion
Reversible adhesion of the bacterium and the surface
The proteins and carbohydrates that are exposed on the bacterial cell surface become important once the bacterial are in loose contact with the acquired enamel pellicle.
12/27/2011
DENTAL PAQUE 35
It results in initial, reversible adhesion of bacteria, initiated by interactions between bacterium & surface through long range & short range forces, including Van der Waals attractive forces & electrostatic repulsive forces.
Derjaguin, Landau, Verwey, & Overbeek (DLVO) theory have been postulated that above a separation distance of 1nm, the summation of previous two forces describes total long range interaction, also called as total Gibbs energy (GTOT).
12/27/2011
DENTAL PAQUE 36
The result of (GTOT=GA+GE )summation is function of a separation distance between negatively charged particle & a negatively charged surface in a medium ionic strength suspension medium.
GTOT for most bacteria consists of secondary minimum (reversible binding takes place: 5-20 nm from the surface), a positive maximum (located at <2nm away from surface), where irreversible adhesion is established.
If a particle reaches primary minimum a group of short range forces dominates adhesive interaction & determines strength of adhesion.
12/27/2011
DENTAL PAQUE 37
Particles in aqueous suspension can acquire charge due to preferential adsorption of ions from solution of certain groups attached to pellicle or surface.
The charge on surface is always exactly balanced by an equivalent number of counter ions; the size of this electrical double layer is inversely proportional to ionic strength of environment.
As particle approaches surface, it experiences a weak van der Waals attraction induced by fluctuating dipoles within the molecules of the two approaching surfaces. This attraction increases as particles moves closer to substratum.
A repulsive force is encountered if the surface continue to approach each other due to overlap of electrical double layers.
12/27/2011
DENTAL PAQUE 38
ATTACHMENT
12/27/2011
Adhesins
DENTAL PAQUE 39
Attachment
A firm anchorage between bacterium and surface will be established by specific interactions ( ionic, covalent, or hydrogen bonding)
12/27/2011
DENTAL PAQUE 40
Adhesins
Adhesins can be subdivided into two major classes: Fimbrial adhesins, including fimbriae, pili, curli
and type IV pili, Nonfimbrial adhesins, such as
autotransporter, outer membrane and secreted adhesins,
Those associated with biofilm formation
Periodontology 2000, Vol. 52, 2010, 12–37
12/27/2011
DENTAL PAQUE 41
Fimbrial adhesins
Fimbrial adhesins of gram-negative bacteria are classified into five major classes – Chaperone–usher (CU) pili, Curli, Type IV pili, Type III secretion pili and Type IV secretion pili – based on their
biosyntheticpathway
12/27/2011
DENTAL PAQUE 42
Curli
Curli are thin aggregative fimbriae identified as a new type of fimbrial adhesin expressed on the outer surfaces of some Enterobacteriaceae, such as Escherichia and Salmonella spp.
Curli promote bacterial adhesion to and invasion of the host, as well as biofilm formation, and they also function as a potent promoter of host pro-inflammatory responses.
12/27/2011
DENTAL PAQUE 43
Chaperone–usher pili
Pili (from Latin for hairs) and fimbriae (from Latin for threads) are thin, filamentous, proteinaceous surface appendages (hair-like organelles) that protrude from the surface of many different bacterial species and are especially prominent on gram-negative bacteria where they are anchored within the outer membrane.
12/27/2011
DENTAL PAQUE 44
Type IV pili
Type IV pili are extruded across the outer membrane and form long and flexible surface appendages expressed by major human pathogens, such as Neisseria gonorrhoeae, Neisseria meningitidis, Pseudomonas aeruginosa, Vibrio cholerae, Salmonella enterica, Legionella pneumophila and the enteropathogenic E. coli.
It is quite remarkable that type IV pili assembly can be reversed and retracted through the bacterial cell wall.
12/27/2011
DENTAL PAQUE 45
Fimbriae:
• Are proteinaceous hair like appendages • Composed of protein subunits called fimbrillin• Fimbriae also carry adhesins
Fimbriae of oral strain are thin, flexible and 2-3nm in diameter, thus differing from larger more rigid filmbriae found on other bacteria such as eschericia coli
•Fibrils are also found oral bacterial species e.g. S. mitis, Prevotella intermedia, Prevotella nigrescens and S. mutans.
12/27/2011
DENTAL PAQUE 46
•A naeslundi is one of the most imp colonizing species on tooth surfaces. Two major types of fimbriae are present Type 1:- Are associated with adhesion of A. naeslundi to salivary acidic rich protein and to statherin deposited within salivary pellicle. Type 2: Are associated with attachment to of A.naeslundi to glycosidic receptors an epithelial cells PMNs and oral streptocci
•The lectinase like adhesion to these substrates is inhibited by galactose and N. acetyl galactosamine
12/27/2011
DENTAL PAQUE 47
The best characterized fimbriae of the oral G-ve bacteria are those of P-gingivalis
3 types are present
• They are upto 3m long and 5nm wide, the major class of which is composed of fimbrillin
The fimbrillin polypeptide binds proline rich proteins statherin, lactoferrin, oral epithelial cells, oral streptococci
Fimbrae of P.g exhibit chaemotactic properties and demonstrate cytokine induction, both of which are necessary for P.g to invade epithelial cells
12/27/2011
DENTAL PAQUE 48
Host Bacterial Interactions Involved In Adhesion
Bacterium Adhesin Receptor
Streptococcus spp Antigen 1/11 Salivary agglutinin
Streptococcus spp LTA Blood group reactive proteins
Mutans streptococci Glucan binding protein
Glucan
Streptococcus parasanguinis
35 kDA lipoprotein Fibrin, pellicle
Actinomyces naelslundii
Type 1 fimbriae Proline-rich proteins
Porphyromonas gingivalis
150 kDA protein Fibrinogen
Prevotella loescheii 70 kDA lectin Galactose
Fusobacterium nucleatum
42 kDA protein Coaggregation with P. gingivalisOral microbiology 4th edition, Philip Marsh
12/27/2011
DENTAL PAQUE 49
Other factors that help in attachment of bacteria
• Force generating movement is an important first step in biofilm formation by G-ve bacteria
• Active motility due to the production of flagella or twitching mobility due to type IV pili are thought to increase the no of initial interactions between bacterial cells and solid surfaces and to help overcome initial repulsive forces between bacteria and the surface.
• Cell surface proteins of staphylococcus epidermidis and Caulobacter crescentus are imp in initial attachment. •Polysaccharide adhesion of S. epidermidis 12/27/2011
DENTAL PAQUE 50
COLONIZATION
12/27/2011
Primary and secondary colonizersCo aggregationTest tube brush
DENTAL PAQUE 51
Colonization and plaque maturation
Co aggregation - cell to cell recognition of genetically distinct
partner cell types
12/27/2011
DENTAL PAQUE 52
Primary colonizers
They provide new binding sites for adhesion by other oral bacteria.
The metabolic activity of the primary colonizers modifies the local micro environment which influences the ability of other bacteria to survive in the dental plaque biofilm.
12/27/2011
DENTAL PAQUE 53
Primary colonizers
12/27/2011
DENTAL PAQUE 54
Secondary colonizers
They do not initially colonize the clean tooth surface but adhere to bacteria already in the plaque mass.
12/27/2011
DENTAL PAQUE 55
Secondary colonizers
12/27/2011
DENTAL PAQUE 56
•Primary colonization bypredominantly Gram-positive facultativebacteria. Ss: Streptococcussanguis is most dominant. Av : Actinomyces spp. are also found in 24h plaque.• Gram-positive facultativecocci and rods co-aggregate andMultiply.
12/27/2011
DENTAL PAQUE 57
Surface receptors on theGram-positive facultative cocciand rods allow the subsequent adherence of Gram-negative organisms, which have a poor ability to directly adhere to the pellicle.Fn: Fusobacterium nucleatum.BI: Prevotella intermedia.
12/27/2011
DENTAL PAQUE 58
The heterogeneity increasesas plaque ages and matures.As a result of ecologicchanges, more Gram-negativestrictly anaerobic bacteria colonizesecondarily and contribute to anincreased pathogenicity of thebiofilm.
12/27/2011
DENTAL PAQUE 59
Co aggregation
It was described by Gibbsons & Nygaard Corncob formation - Streptococci adheres
to filaments of bacterionema matruchotti or actinomyces species
Test tube brush – composed of filamentous bacteria to which gram negative rods adhere.
12/27/2011
DENTAL PAQUE 60
• Significance of co aggregation has been highlighted (Kollenbrander 1989, 1995, 1993) in various in vitro & in vivo studies.
• F.nucleatum is central to the mechanism - since this organism can co aggregate with numerous other species.
• Examples F.nucleatum - S.sanguis P. loescheii A.viscous Capnocytophaga P.gingivalis B.forsythus T.denticola
12/27/2011
DENTAL PAQUE 61
18 new genera from oral cavity show co aggregation
-Cell to cell recognition of genetically distinct partner cell types (Kolen brander PE et al 1993)
-Through the highly specific steriochemical interaction of protein and carbohydrate molecules located on the bacterial cell surface.
-Mediated by lectinlike adhesins and can be inhibited by lactose and other galactosides
-Coaggregation concept opens new perspectives, especially for the use of probiotics
12/27/2011
DENTAL PAQUE 6212/27/2011
DENTAL PAQUE 63
S.mitisS.oralis
S.sanguis
Streptococcus spsS.gorondi,S.intermedius
EARLYCOLONIZERS
V.parvulaA.odontolyticus
P.intermediaP.nigrescensP.microsF.nucleatum
C.rectus
E.nodatum
C.showae
E.corrodens Capnocytophaga spsA.actinomycetocomitans
P.gingivalisT.forsythusT.denticola
CLOSELY ASSOCIATEDCOMPLEXES IN THE ORAL CAVITY
LATE COLONIZERS
12/27/2011
DENTAL PAQUE 64
Socransky SS, Haffajee et al, “micro biel complexes in subgingival plaque” JCP 14: 588, 1987
12/27/2011
DENTAL PAQUE 65
Physiologic properties of dental plaque
Early colonizers: use oxygen and lower the redox potential, which then favours growth of anaerobic bacteria• streptococci• actinomyces
Gram positive species:• use sugars
as an energy sources
• and saliva as a carbon source
Bacteria in mature plaque: use amino acids and small peptides as energy sources• anaerobic• asaccharol
ytic
Bacteria like p. gingivalis use by products of other bacteria• Such as
succinate from capnocytophaga ochraceus
• Protocheme from campylobacter rectus
12/27/2011
DENTAL PAQUE 66
Host – as important source of nutrients
Bacteria degrade host proteins to
release ammonia which is used by
another baceria as a nitrogen source.
p. Gingivalis uses hemin iron from
the breakdown of host haemoglobin.
Prevotella intermedia proportions
increases with steroid increase in
host.
12/27/2011
DENTAL PAQUE 67
Ecological plaque hypothesis
In 1990, Marsh et al developed the ecologic plaque hypothesis
According to this, both the total no. of dental plaque and the specific microbial composition of plaque may contribute to the transition from health to disease.
A change in the nutrient status of a pocket or chemical and physical changes to the habitat are thus considered the primary cause for overgrowth by pathogens
12/27/2011
DENTAL PAQUE 68
New treatment concepts : Alter the local environment by reducing the
crevicular flow rate, or The site made less anaerobic by the use of
redox agents
12/27/2011
DENTAL PAQUE 69
De Novo Supragingival Plaque Formation: Clinical Aspects
During 1st 24 hrs, starting from a clean tooth surface, plaque growth is negligible from clinical view point.
Following 3 days, plaque growth increases at a rapid rate, then slows down.
After 4 days, on average 30% of total tooth crown area will be covered with plaque. Plaque does not seem to increase substantially after 4th day.
There will be a shift towards anaerobic & gram negative flora, including an influx of Fusobacteria, filaments, spiral forms & spirochetes.
12/27/2011
DENTAL PAQUE 70
Topography of supragingival plaque:
Initial plaque formation takes place along the gingival margin & from interdental space, later further extension in coronal direction can be observed.
Plaque formation can also start from grooves, cracks, perikymata, or pits
Scanning electron microscopy reveals that early colonization of enamel surface starts from surface irregularities, where bacteria escape shear forces allowing time needed to change from reversible to irreversible binding.
12/27/2011
DENTAL PAQUE 71
Surface microroughness:
Rough intraoral surfaces accumulate & retain more plaque & calculus in terms of thickness, area & colony forming unit.
Smoothing intraoral surfaces decreases rate of plaque formation.
There seems to be threshold for surface roughness {Ra 0.2 micrometers}, above which bacterial adhesion is facilitated.
12/27/2011
DENTAL PAQUE 72
Variation within dentition:
Early plaque formation occurs faster.1. In lower jaw, compared to upper jaw.2. In molars areas.3. On buccal tooth surfaces, compared to
oral sites.4. In interdental regions compared to strict
buccal or oral surface.
12/27/2011
DENTAL PAQUE 73
Impact of gingival inflammation:
Plaque formation is more rapid on tooth surfaces facing inflamed gingival margins, than those facing healthy gingivae. Studies suggest that increase in crevicular fluid production enhances plaque formation, it favors initial adhesion & colonization of bacteria.
12/27/2011
DENTAL PAQUE 74
Impact of patient age:
Subject’s age does not influence de novo plaque formation.
Plaque developed in older patients resulted in more severe gingival inflammation, which indicates an increased susceptibility to gingivitis with aging.
12/27/2011
DENTAL PAQUE 75
De Novo Subgingival Plaque Formation
Early studies, using culturing techniques examined changes in subgingival microbiota during 1st week after mechanical debridement, partial reduction followed by fast regrowth to almost pre treatment levels within 7 days.
This reveals that a high proportion of treated tooth surfaces still harbored plaque & calculus after scaling, these remaining bacteria were considered primary source for subgingival recolonization.
12/27/2011
DENTAL PAQUE 76
Oral implants have been used as model to study impact of surface roughness on subgingival plaque formation.
Bollen CM, et al “ The influence of abutment surface roughness on plaque accumulation and peri – impalnt mucositis” clin oral implants res 7: 201;1996
Smooth abutments were found to harbor 25 times less bacteria than rough ones, with a slightly higher density for coccoid cells.
Subgingival microflora was largely dependent on remaining presence of teeth & degree of periodontitis in remaining natural teeth.
12/27/2011
DENTAL PAQUE 77
Ageing & Microflora
Following tooth eruption the isolation frequency of spirochetes & black pigmented anaerobes increases.
Increased prevalence of spirochetes & black pigmented anaerobes is found in teenagers, this is due to hormones entering gingival crevice & acting as a novel nutrient source.
Rise in P. intermedia in plaque during 2nd trimester of pregnancy has been ascribed due to elevated levels of oestradiol & progesterone which supplies napthoquinone for growth of this microorganism.
12/27/2011
DENTAL PAQUE 78
Oral microflora
Direct effects
Indirect effects
•Cell mediated immunity wanes•Changes in salivary antibodies•Hormonal changes•Altered physiology of oral mucosa
•Denture wearing•Medication•Cancer therapy•Dietary changes
12/27/2011
Effects on oral microflora
DENTAL PAQUE 79
Plaque As a BioFilm
The term biofilm describes the relatively undefinable microbial community associated with a tooth surface or any other hard, non-shedding material (Wilderer & Charaklis 1989)
Biofilms have an organized structure. They are composed of micro colonies of bacterial cells
non randomly distributed in a shaped matrix or glycocalyx.
In lower plaques layers microbes are bound together in polysaccharide matrix with other organic & inorganic materials.
On top of lower layer, a loose layer appears that is often irregular in appearance; it can extend into surrounding medium.
12/27/2011
Where can we find them?
In a pipe
Plaque on the teeth
In a Creek
In a membrane
Properties of Biofilm
• Survival of the bacterial community as a whole
• Metabolic cooperativity
• Have a primitive circulatory system
• Numerous microenvironments
• Resistant to host defenses
• Resistant to antibiotics and antimicrobials
DENTAL PAQUE 82
Bacteria in bio - films
Resistant of bacteria to antimicrobial agents is increased in the biofilm.
Almost 1000 to 1500times more resistant to antibiotics than in their planktonic stage
Why increased resistance????? Nutrional status Growth rate Temperature pH Prior exposure to sub – effective conc. Of
antimicrobial agents.12/27/2011
DENTAL PAQUE 83
Bio film
Certain properties that resists diffusion like; strongly charged or chemically highly reactive agents fail to reach the deeper part of bio film because biofilm acts as an ion- exchange resin, removing such molecules from solution.
Recently “super resistant” bacteria were identified; the cells have multidrug resistant pumps that can extrude antimicrobial agents from the cell.
12/27/2011
DENTAL PAQUE 8412/27/2011
Good morning
DENTAL PAQUE 85
IMPORTANT FEATURES OF BIOFILM
12/27/2011
Communications in Biofilm
• Genetic expression is different in biofilm bacteria when compared to planktonic (free floating) bacteria.
• Biofilm cells can coordinate behaviorvia intercellular "communication“ using biochemical signaling molecules.
Quorum sensing
• Involves the regulation of expression of specific genes through the accumulation of signaling compounds that mediate intercellular communication
• Dependent on cell density and mediated through signaling compounds
• Quorum sensing gives biofilms their distinct properties
Quorum sensing is involved in the regulation of
genetic competencematingbacteriocin productionsporulationstress responsesvirulence expressionbiofilm formationbioluminescence
Competence is a physiological state in which bacteria develop a capacity to take up exogenous DNA (Dubnau, 1991)
It is an elaborate process involving multiple protein components and sophisticated regulatory networks
It is important to ensure that a DNA pool is available when the cells become competent.
• In S.mutans ,quorum sensing is mediated by a competence stimulating peptide (CSP)
• This peptide also induces genetic competence so that the transformation frequency of biofilm grown S.mutans was 10 to 600 fold greater than for planktonic cells
DENTAL PAQUE 91
Principle of Bacterial Transmission, Translocation OR Cross Infection
Intraoral transmission of bacteria from one niche to another is called translocation or cross infection.
Christersson et al. demonstrated translocation of A.a by periodontal probes in patients with localized aggressive periodontitis.
12/27/2011
DENTAL PAQUE 92
Translocation & Mechanical Debridement
To reduce the chance of intraoral translocation “one stage mouth disinfection” was introduced by Leuven group in 1990
This strategy attempts to eradicate, or at least suppress periodontal pathogens in a short time not only from periodontal pocket, but also from their habitats.
Several studies illustrate benefits of one stage full mouth disinfection approach in relation to:
1. Gain in attachment2. Pocket depth reduction3. Microbiologic shifts
12/27/2011
DENTAL PAQUE 93
Microbial Specificity of Periodontal Diseases
Non Specific Plaque Hypothesis
Specific Plaque Hypothesis
12/27/2011
DENTAL PAQUE 94
Non Specific Plaque Hypothesis
The nonspecific and specific plaque hypotheses were delineated in 1976 by Walter Loesche
The nonspecific plaque hypothesis maintains that periodontal disease results from the "elaboration of noxious products by the entire plaque flora.
According to this thinking, when only small amounts of plaque are present, noxious products are neutralized by the host.
Similarly, large amounts of plaque would produce large amounts of noxious products, which would essentially overwhelm the host's defenses.
Nonspecific plaque hypothesis is the concept that control of periodontal disease depends on control of the amount of plaque accumulation.
Treatment of periodontitis by debridement (nonsurgical or surgical) and oral hygiene measures focuses on the removal of plaque and its products and is founded in the nonspecific plaque hypothesis.12/27/2011
DENTAL PAQUE 95
Specific Plaque Hypothesis
The specific plaque hypothesis states that only certain plaque is pathogenic, and its pathogenicity depends on the presence of or increase in specific microorganisms.
This concept predicts that plaque harboring specific bacterial pathogens results in periodontal disease because these organisms produce substances that mediate the destruction of host tissues.
12/27/2011
DENTAL PAQUE 96
Socransky's criteria for periodontal pathogens
ASSOCIATION: A pathogen should be found more frequently and in higher numbers in disease states than in healthy states
ELIMINATION: Elimination of the pathogen should be accompanied by elimination or remission of the disease.
12/27/2011
DENTAL PAQUE 97
HOST RESPONSE: There should be evidence of a host response to a specific pathogen which is causing tissue damage.
VIRULENCE FACTORS: Properties of a putative pathogen that may function to damage the host tissues should be demonstrated.
ANIMAL STUDIES: The ability of a putative pathogen to function in producing disease should be demonstrated in an animal model system. 12/27/2011
DENTAL PAQUE 98
The two periodontal pathogens that have most thoroughly fulfilled Socransky's criteria are Actinobacillus actinomycetemcomitans in the form of periodontal disease known as Localized Juvenile periodontitis (LJP), and Porphyromonas gingivalis in the form of periodontal disease known as adult periodontitis.
12/27/2011
DENTAL PAQUE 99
Evidence implicating as a periodontal pathogen(Adapted from Socransky,
1992) CRITERION OBSERVATIONS
Association Elevated in lesions of Juvenile Periodontitis, and some lesions of Adult Periodontitis
Elevated in "active" Localized Juvenile Periodontitis (LJP) lesions
Detected in apical region of periodontal pocket or in tissues of LJP lesions
Unusual in health or gingivitis Elimination Elimination associated with clinical
resolution of disease Species found in recurrent lesions Host Response Elevated systemic and local antibody
levels in Juvenile Periodontitis Virulence Factors Leukotoxin, collagenase, endotoxin,
epitheliotoxin, fibroblast inhibitory factor, bone resorption-inducing factor
Animal Studies Disease induced in gnotobiotic rats 12/27/2011
DENTAL PAQUE 100
Evidence implicating P. gingivalis as a periodontal pathogen (Adapted from
Socransky, 1992)
CRITERION OBSERVATIONS
Association Microorganism is elevated in periodontitis lesions Unusual in health or gingivitis
Elimination Suppression or elimination results in clinical resolution
Species found in recurrent lesions Host Response Elevated systemic and local
antibody in periodontitis Virulence Factors Collagenase, trypsin-like enzyme,
fibrinolysin, immunoglobulin degrading enzymes, other proteases, phospholipase A, phosphatases, endotoxin, hydrogen sulfate, ammonia, fatty acids and other factors that compromise PMN function
Animal Studies Onset of disease correlated with colonization in monkey model
Key role in mixed infections in animal models 12/27/2011
DENTAL PAQUE
MICROORGANISMS ASSOCIATED WITH
SPECIFIC PERIODONTAL DISEASESPERIODONTAL HEALTH
102 to 103 bacteria. Certain bacterial species have been proposed to be beneficial to the
host, including S. sanguis, Veilonella parvula, and C. ochraceus(Carranza 10th)
Bacteria associated with periodontal diseases are often found in the subgingival microflora at healthy sites, although they are normally present in small proportions(Rose & Maeley, 6th)
Nonmotile nature.
10112/27/2011
DENTAL PAQUE
GINGIVITIS 104 to 106 bacteria. Gram-negative bacteria. Compared with healthy sites, noticeable increase also occur in the
numbers of motile bacteria, including cultivable and uncultivable treponemas (spirochetes).
Pregnancy associated gingivitis is accompanied by dramatic increases in levels of P. intermedia, which uses the steroid as growth factors(Carranza,10th )
10212/27/2011
DENTAL PAQUE
CHRONIC PERIODONTITIS C. rectus, P. gingivalis, P. intermedia, F. nucleatum and T. forsythia
were found to be elevated in the active sites(Carranza,10th ) Sites with chronic periodontitis will be populated with greater
proportions of gram-negative organisms and motile bacteria. Certain gram-negative bacteria with pronounced virulence
properties have been strongly implicated as etiologic agents e.g. P. gingivalis and Tannerella forsythus.
10312/27/2011
DENTAL PAQUE
LOCALIZED AGGRESSIVE PERIODONTITIS
Gram -ve, and anaerobic rods. The most numerous isolates are several species from the
genera Eubacterium, A. naeslundii, F. nucleatum, C. rectus, and Veillonella parvula.
In some populations, a strong case can be made for Aa playing a causative role in LAP, especially in cases in which patients harbor highly leukotoxic strains of the organism.
However, some populations of patients with LAP do not harbor Aa, and in still others P. gingivalis may be etiologically more important.
10412/27/2011
DENTAL PAQUE
GENERALIZED AGGRESSIVE PERIODONTITIS
The sub-gingival flora in patients with generalized aggressive peri odontitis resembles that in other forms of periodontitis.
The predominant subgingival bacteria in patients with generalized aggressive periodontitis are P. gingivalis, T. forsythis A. actinomycetemcomitans, and Campylobacter species.
10512/27/2011
DENTAL PAQUE
REFRACTORY CHRONIC PERIODONTITIS
Unusually diverse and may contain enteric rods, staphylococci, and Candida.
Persistently high levels are found of one or more of P. gingivalis, T. forsythis, S. inter-medius, P. intermedia, Peptostreptococcus micros, and Eikenella corrodens.
Persistence of Streptococcus constellatus has also been reported.
10612/27/2011
DENTAL PAQUE
NECROTIZING ULCERATIVE GINGIVITIS/PERIODONTITIS
More than 50% of the isolated species were strict anaerobes with P. gingivalis and F. nucleatum accounting for 7-8% and 3.4%, respectively.
10712/27/2011
DENTAL PAQUE
PERIODONTAL ABSCESSES
The bacteria isolated from abscesses are similar to those associated with chronic and aggressive forms of periodontitis.
An average of approximately 70% of the cultivable flora in exudates from periodontal abscesses are gram-negative and about 50% are anaerobic rods.
Periodontal abscesses revealed a high prevalence of the following putative pathogens: F. nucleatum (70.8%), P. micros (70.6%), P. intermedia (62.5%), P. gingivalis (50.0%), and T. forsythis (47.1%).
Enteric bacteria, coagulase-negative staphylococci, and Candida albicans have also been detected.
10812/27/2011
DENTAL PAQUE
PERIIMPLANTITIS High proportion of anaerobic gram negative
rods, motile organisms, and spirochetes). Species such as Aa, Pg, Tf, P. micros, C. rectus,
Fusobacterium, and Capnocytophaga are often isolated from failing sites.
Other species such as Pseudomonas aeruginosa, enterobacteriaceae, Candida albicans and staphylococci, are also frequently detected around implants.
10912/27/2011
DENTAL PAQUE
PEPTOSTREPTOCOCCUS MICROS
P. micros is a Gram positive, anaerobic, small, asaccharolytic coccus.
Two genotypes can be distinguished with the smooth genotype being more frequently associated with periodontitis lesions than the rough genotype (Kremer et al. 2000).
P. micros was found to be in higher numbers at sites of periodontal destruction as compared with healthy sites (Papapanou et al 2000, Riggio et al 2001).
It was shown that P. micros in combination with either P. intermedia or P. nigrescens could produce transmissible abscesses (Van Dalen et al 1998).
Produce protease(Grenier 2006)
11012/27/2011
DENTAL PAQUE
SALMONELLAS SPECIES
The salmonellas spp. are Gram negative, curved, saccharolytic rods and may be recognized by their curved shape, tumbling motility and, in good preparations, by the presence of a tuft of flagella inserted in the concave side.
Moore et al (1987) described six genetically and phenotypically distinct groups isolated from oral cavity and found S. noxia at a higher proportion of shallow sites (PD>4mm) in chronic periodontitis.
11112/27/2011
DENTAL PAQUE
EUBACTERIUM SPECIES Suggested as possible periodontal pathogens due to
their increased levels in disease sites. (Moore et al 1985).
E. nodatum, Eubacterium brachy and Eubacterium timidum are Gram positive, strictly anaerobic, small somewhat pleomorphic rods.
Some of these species elicited elevated antibody responses in subjects with destructive periodontitis. (Martin et al 1988)
11212/27/2011
DENTAL PAQUE
MILLERI STREPTOCOCCI Some of the streptococcal species are
associated with and may contribute to disease progression.
Milleri streptococci, Streptococcus anginosus, S. constellatus and S. intermidius might contribute to disease progression in subsets of periodontal patients.
These species was found to be elevated at sites which demonstrated recent disease progression (Dzink et al 1988).
11312/27/2011
DENTAL PAQUE
OTHER SPECIES
Emphasis have been placed on enteric organisms, staphylococcal species as well as other unusual mouth inhabitants.
Slots et al (1990)
11412/27/2011
DENTAL PAQUE
VIRUSES Contreras & Slots 2000, Kamma et al 2001
11512/27/2011
DENTAL PAQUE 116
Viral diseases of the oral mucosa and the perioral region are often encountered in dental practice. Viruses are important ulcerogenic and tumorigenic agents of the human mouth.
12/27/2011
DENTAL PAQUE 117
Four major viral families are associated with the main viral oral diseases of adults, as follows:
1. The group of herpesviruses contains eight different members that all are enveloped double-stranded DNA viruses. In the oral cavity, they are related to different ulcers, tumors, and other oral pathoses.
2.Human papillomaviruses are grouped within five genera and are nonenveloped double-stranded DNA viruses. In the oral cavity, they are related to ulcers, tumors, and oral pathoses.
12/27/2011
DENTAL PAQUE 118
3. Picornaviruses are all nonenveloped, single-stranded RNA viruses. In the oral cavity, they are related to ulcers and different oral pathoses
4. Retroviruses are divided into seven genera of which two are human pathogens. All retroviruses are enveloped single-stranded RNA viruses. In the oral cavity, they are related to different tumors and oral pathoses.
12/27/2011
DENTAL PAQUE
Herpesviruses are capable of infecting various types of cells, including polymorphonuclear leukocytes, macrophages, and lymphocytes.
The diffuse invasion of Candida fungi and other opportunistic organisms into the gingival tissue of AIDS patients has been demonstrated to be a typical virus-mediated alteration of host defense mechanisms.
Shobha Prakash, Sushma Das (2006) concluded that HSV-1 and EBV are significantly associated with destructive periodontal disease including chronic and aggressive periodontitis. HSV-1 detected sites in relation to pocket depth and clinical attachment level were found to be significant indicating that it is associated with severity and progression of destructive periodontal disease.
11912/27/2011
DENTAL PAQUE 12012/27/2011
DENTAL PAQUE
FUNGI Hannula J, Dogan B, Slots (2001) showed
geographical differences in the subgingival distribution of C. albicans serotypes and genotypes and suggested geographic clustering of C. albicans clones in Subgingival samples of Chronic Periodontitis patients.
Reynaud AH (2001) found a weak correlation between yeasts in periodontal pockets.
12112/27/2011
DENTAL PAQUE
MIXED INFECTIONS At the pathogenic end of the spectrum, it is conceivable
that different relationships exist between pathogens. The presence of two pathogens at a site could have no
effect or diminish the potential pathogenicity of one or other of the species.
Alternatively, pathogenicity could be enhanced either in an additive or synergistic fashion.
It is not clear whether the combinations suggested in the experimental abscess studies are pertinent to human periodontal diseases
12212/27/2011
DENTAL PAQUE 123
ARCHAEA
Single celled organism that are distinct from the bacteria.
Methanogenic archaea produce methane gas from hydrogen gas, carbon dioxide
Isolated from patients with periodontal disease by enriching cultures with H2 and CO2.
12/27/2011
DENTAL PAQUE 124
References
1.Dental Plaque: biological significance of a biofilm and community life style P.D.Marsh – JCP- 2005
2.Oral biofilms and Calculus – text book of Clinical periodontology and Implant dentistry - Jan Lindhe, Lang and Karring – 5th Edition
3.Periodontal microbial Ecology – Socransky and Haffajee Periodontology 2000 – Volume 38 – 2005
4.Microbiology of Periodontal diseases: Genetics, Polymicrobial communities, selected pathogens and treatment. Haffajee and socransky - Peridontology 2000, Volume 42, 2006
12/27/2011
DENTAL PAQUE 125
References
5.Communication among Oral Bacteria Paul E. Kolenbrander,* Roxanna N. Andersen, David S. Blehert, G. Egland,Jamie S. Foster, and Robert J. Palmer Jr. MICROBIOLOGY AND MOLECULAR BIOLOGY REVIEWS, Sept. 2002
6.Interspecies Interactions within Oral Microbial Communities Howard K. Kuramitsu,1† Xuesong He,2† Renate Lux,2 Maxwell H. Anderson,3 and Wenyuan Shi2* MICROBIOLOGY AND MOLECULAR BIOLOGY REVIEWS, Dec. 2007
7.Microbial etiology of periodontitis Tatsuji Nishihara & Takeyoshi Koseki Periodontology 2000 Vol-36
12/27/2011
DENTAL PAQUE 126
References
8.Periodontal disease at the Biofilm-Gingival interface Offenbacher et al J.P – Oct 2007
9.Impact of 16S rRNA Gene Sequence Analysis for Identification of Bacteria on Clinical Microbiology and Infectious Diseases Jill E. Clarridge III*` CLINICAL MICROBIOLOGY REVIEWS, Oct. 2004
10.Interspecies interactions within Oral Microbial Communities Howard K.Kuramitsu, Xeusong He, Renate Lux, Maxwell H.Anderson and Wenyuan Shi Microbiology and Molecular Biology Reviews, Dec. 2007
12/27/2011
DENTAL PAQUE 127
References
12/27/2011