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1Dental plaque

2CONTENTSDefinitionClassificationCompositionDental plaque as a biofilmFormationGrowth dynamics of plaqueStructure and physiologic propertiesPlaque hypothesisClinical significancePlaque controlConclusionReferences

3DefinitionSoft deposits that form the biofilm adhering to the tooth surface or other hard surfaces in the oral cavity, including removable and fixed restorations. Bowen,1976

Bacterial aggregation on the teeth or other solid oral structures. Lindhe, 2003

Dental plaque is a specific but highly variable structural entity , resulting from sequential colonization of microorganisms on the tooth surfaces, restorations and other parts of oral cavity , composed of salivary components like mucin, desquamated epithelial cells, debris and microorganisms , all embedded in extracellular gelatinous matrix. WHO, 1961 4CLASSIFICATION

By location on tooth

supra gingival plaque sub gingival plaque

coronal marginal attached unattached

tooth tissue epithelium55Supragingival plaque

1.Found at or above the gingival margin

2.Inorganic components derived from saliva

3.Gram +ve organisms predominate

4. Few motile bacteria

5. Metabolism: predominantly carbohydrates

6. Supra gingival plaque is associated with calculus formation and root caries

Subgingival plaque

1.Found below gingival margin

2.Inorganic components are derived from crevicular fluid

3. Gram ve organisms predominate

4. Motile bacteria are common

5. Metabolism: predominantly proteins

6. Sub gingival plaque is associated with tissue destruction seen in periodontitis

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8Composition

Primarily composed of microorganisms. One gram of plaque contains approx. 2 x 1011 bacteria.More than 325 different bacterial species may be found in plaque.

9Previous ClassificationNew ClassificationReferenceBacteroides gingivalisPorphyromonas gingivalisShah and Collins,1988Bacteroides endodontalisPorphyromonasendodontalisShah and Collins, 1988Bacteroides intermediusPrevotella intermediaShah and Collins, 1990Bacteroides melaninogenicusPrevotella melaninogenicaShah and Collins, 1990Bacteroides denticolaPrevotella denticolaShah and Collins, 1990Bacteroides loescheiiPrevotella loescheiiShah and Collins, 1990Wolinella rectaCampylobacter rectusVandamme, et al., 1991Wolinella curvaCamplyobacter curvusVandamme, et al., 199110SELECTED BACTERIAL SPECIES FOUND IN DENTAL PLAQUEFacultativeAnaerobicGram-PositiveStreptococcus mutansStreptococcus sanguisActinomyces viscosusGram-negativeActinobacillusactinomycetemcomitansCapnocytophypaspeciesEikenella corrodensPorphyromonas gingivalisFusobacterium nucleatumPrevotella intermediaBacteroides forsythusCampylobacter rectusSpirochetesTreponema denticola(OtherTreponemaspecies)11Non bacterial microorganisms that are found in plaque include mycoplasma species, yeasts, protozoa, viruses.

The microorganisms exist within an intercellular matrix that also contain few host cells, such as epithelial cells, macrophages and leucocytes.12Intercellular matrixTakes up nearly 25% of dental plaque volume. Consists of organic and inorganic materials.Forms a hydrated gel in which the embedded bacteria exist and proliferate. This gel like matrix is a primary characterstic of biofilms. Matrix is thought to protect resident bacteria from substances such as antimicrobial agents, which may be unable to diffuse through the matrix to reach the bacterial cells.

1314Organic constituentsPolysaccharide ProteinsAdhesive95% Dextrans Bacterial colonization5% levansStorage of polysaccharide Source of fermentable carbohydrateAlbuminOriginating from GCF15GlycoproteinsLipid materialImportant component of plaque pellicle. Debris from membranes of disrupted bacteria, host cells and possibly food debris.16Inorganic constituentsSupragingival plaque Subgingival plaque FluoridePrimarily salivaCrevicular fluid Fluoridated tooth pastes and rinsesRemineralisation of tooth structure Prevention of demineralization of tooth structureInhibition of the growth of many plaque microorganisms17DENTAL PLAQUE AS A BIOFILM

Biofilms defined as matrix enclosed bacterial populations adherent to each other and/or to surfaces or interfaces. (costerton,1994) Formed by a single bacterial species or multiple bacterial species as well as other organisms & debris.Form on any surfaces that is wet.Exist on any solid surfaces that is exposed to bacteria-containing fluid.

18Biofilm structureThe bacteria in a biofilm are not distributed evenly, they cluster together to form sessile mushroom shaped microcolonies.

Each microcolony is an independent community containing thousands of compatible bacteria, with its own customised living environment.

19Bacteria in the center of a microcolony may live in a strict anaerobic environment, while other bacteria at the edges of the fluid channel may live in an aerobic environment

20A series of fluid channels penetrates the extracellular slime layer. These provide nutrients and oxygen for the bacterial micro colonies and facilitate movement of bacterial metabolites, waste products, and enzymes within the biofilm structure.

2121Each bacterial microcolony uses chemical signals to create a primitive communication system used to communicate with other bacterial microcolonies.

22The extracellular slime layer is a protective barrier that surrounds the mushroom shaped bacterial microcolonies. The slime layer protects the bacterial microcolonies from antibiotics, antimicrobials, and host defense mechanisms. Can be destroyed by simply wiping them off.

23Formation of plaque Can be divided into 3 stages:Formation of dental pellicleInitial colonization by bacteriaSecondary colonization and plaque maturation24Formation of dental pellicle2526The hydroxyapatite surface consists of negatively charged phosphate groups that interact directly or indirectly with positively charged components of salivary and crevicular fluid macromolecules.27

Initial colonization of the tooth surface by bacteria

2829Secondary colonization and plaque maturation303132 Most studies have focused on interactions between different gram positive species and between gram positive and gram negative species. In the later stages of plaque formation, coaggregation between different gram negative species is likely to predominate. Eg of this type of interaction is the coaggregation of F.nucleatum with P.gingivalis.GROWTH DYNAMICS OF DENTAL PLAQUEImportant changes in the plaque growth can be detected within the first 24 hours.

During the first 2 to 8 hour, Streptococci saturate the salivary pellicle binding sites,covering 3% to 30% of the enamel surface.

Instead of the expected steady growth during the next 20 hours, a short period of rapid growth is observed.

33After 1 day, the term Biofilm is fully deserved because organization takes place within it.

As the bacteria densities approaches approximately 2 to 6 million bacteria/ mm2 on the enamel surface, a marked increase in growth rate can be observed to 32 million bacteria / mm2.

The thickness of the plaque increase slowly with time, increasing to 20 to 30 micrometer after 3 days.

34physiologic properties of dental plaqueTransition from gram positive to gram negative in dental plaque is paralleled by a physiologic transition in the developing plaque.Early colonizers oxygen lower the reduction oxidation potential of the environment favors the growth of anaerobic organisms. Gram positive sugar as a energy source and saliva as carbon source.Anaerobic bacteria amino acids and small peptides as energy source.

35Many physiologic interactions among different bacteria are found in plaque:

Lactate and formate byproducts of metabolism of streptococci and actinomyces utilized in the metabolism of other plaque microorganisms.Growth of P.gingivalis enhanced by metabolic byproducts produced by other microorganisms , eg succinate from Capnocytophaga and protoheme from Camphylobacter.

36The host also functions as an important source of nutrients Eg. Bacterial enzymes that degrade host proteins result in release of ammonia which may be used by bacteria as an energy source.Haeme iron from the breakdown of host hemoglobin may be important in the metabolism of P.gingivalis. Increase in steroid hormone are associated with significant increase in the proportion of P.intermedia found in subgingival plaque.3738

Non Specific Plaque HypothesisPeriodontal disease results from the ELABORATION OF NOXIOUS PRODUCTS BY THE ENTIRE PLAQUE FLORA

According to this theory, Small amount of plaque = Noxious products neutralized by host. Large amount of plaque = large amount of noxious products overwhelms the host defense .

39However this was CONTRADICTED based on certain conclusions ::

First some individuals with considerable amount of plaque & calculus, as well as gingivitis never developed destructive Periodontitis.

Also individual who did present with Periodontitis demonstrated considerable site specificity in the pattern of disease, some sites were unaffected, where as advanced disease was found in adjacent sites.

40Specific Plaque HypothesisIt states that only certain plaque is pathogenic & its pathogenicity depends on the presence of or increase in specific microorganisms. (Loesche W 1976)

It means plaque harbors specific bacterial pathogens resulting in a periodontal disease bcoz these organisms produce substances that mediate the destruction of host tissue E.g. A. actinomcetemcomitans as a pathogen in localized aggressive Periodontitis.

41CLINICAL SIGNIFICANCEDifferent regions of plaque are significant to different processes associated with disease of teeth and periodontium. Eg: marginal supragingival plaque is of prime importance in the development of gingivitis.Supragingival and tooth associated subgingival plaque are critical in calculus formation and root caries. Tissue associated subgingival plaque is important in the soft tissue destruction characteristic of different forms of periodontitis.

42DETECTION OF PLAQUE

Direct vision : -

Thin plaque may be translucent & therefore not visible.Thick plaque tooth may appear dull & dirty.

43USE OF EXPLORER : - Tactile Examination : When calcification has started it appears slightly rough, otherwise it may feel slippery due to coating of soft , slimy plaqueWhen no plaque is visible , an explorer can be passed over the tooth surface & when plaque is present it will adhere to explorer tip. This technique is used when evaluating plaque index. 3. Use of disclosing solutions

44Plaque control Removal of microbial plaque and the prevention of its accumulation on the teeth and adjacent gingival surfaces.

ChemicalMechanical45Mechanical plaque controlTooth brushesManual toothbrushElectrical toothbrush Interdental cleaning aids dental flosswooden tips or rubber tipsInterdental brushes Proxa brushes Unitufted brush Miniature bottle brushOral irrigation devices

46 manual Toothbrushes

According to The American Dental Association: Brushing surface of 1-1.25 inches (25.4 to 31.8mm) long

5/16 to 3/8 inch (7.9-9.5mm) wide

2 to 4 rows of bristles

5-12 tufts per row47Parts of a brush

48Brushing plane

49Filaments

Hard and softNatural and syntheticMultitufted and space tufted

Advantages of nylon filaments over natural bristles

rinse clean and dry rapidly when left in open.More durable and maintain their form longer.Ends rounded and closed,repel water and debris.More resistant to acculumation of bacteria and fungi than are natural bristles.

50Methods of brushing5152Bass technique

53Modified Stillman technique Like the Bass Method the filaments are placed at a 45 angle to the tooth. Unlike the Bass Method the filaments are placed half in the sulcus and half on the gingiva.The same stroke is used as the Bass

54CHARTERS METHODPosition the filaments toward the chewing surface of the toothPlace the sides of the filaments against the enamel and angle them at a 45 to the tooth. Vibrate the filaments gently but firmly, keeping the filaments against the tooth. Reposition on the next set of teeth.

55Fones TechniqueTechnique that uses large, sweeping, scrubbing circles with the toothbrush held at right angles to the tooth surfaces.

With the jaws parted, the palatal and lingual surfaces of the teeth are scrubbed in smaller circles.

Occlusal surfaces of the teeth are scrubbed in an anteroposterior direction.

56Electric toothbrushes In subjects not highly motivated to oral health care, as well as in those having difficulty in mastering a suitable handbrush, "the use of an electric brush with its standard movements may result in more frequent and better cleansing of the teeth".

57Motions: Back and forthCircularEllipticCombinations

Cleaning action by:Mechanical contact between the bristles and the toothLow-frequency acoustic energy generates dynamic fluid movement and provides cleaning slightly away from the bristle tips.

58Interdental cleaning aidsThey are adjunct devices which are used to remove plaque from the interproximal tooth surfaces.The specific aids required for interproximal cleaning depend on various criteria such as the size of the interdental spaces, the presence of furcations, tooth alignment, and the presence of orthodontic appliances and fixed prostheses.59Dental floss Clinical studies clearly show that, when toothbrushing is used together with flossing, more plaque is removed from the proximal surfaces than by toothbrushing alone.

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61Technique

62wooden tipsUsed as an ideal substitute to dental floss in type 2 gingival embrasures.Inserted into the gingival embrasures and remove soft deposits from teeth.Also mechanically stimulate the gingiva.Use is restricted to facial aspect of anterior teeth.63Interdental brushesBest choice of plaque removal from interproximal tooth surfaces in type 2 gingival embrasures.Design is similar to that of bottle brush.Used in posterior areas of mouth.May also be used to clean furcation areas and root concavities.64

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66Oral irrigation devicesMainly beneficial in removal of unattached plaque and debris.Composed of a built in pump and reservoir.When used as an adjunct to tooth brushing these devices have a beneficial effect on periodontal health by retarding plaque and calculus formation.They may also be used to carry antimicrobial agents subgingivally.67

68Chemical plaque controlIdeal requisitesShould decrease plaque & gingivitisPrevent pathogenic growthShould prevent development of resistant bacteriaShould be biocompatibleShould not stain teeth or alter tasteShould have good retentive propertiesShould be economic

6970Vehicles for delivery of chemical agentsTooth Paste Mouth rinses Irrigative Chewing gum VarnishesGel Lozenges 711st Generation Agents

Antibiotics:

PenicillinsTetracyclineVancomycinKenamycin Erythromycin Niddamycin Spiromycin Metronidazole

72Mechanism of Action:Bactericidal or bacteriostatic action.

Limiting factors of systemic drug therapy:

Hypersensitivity reactionsBactericidal resistance

73Phenols Related essential oils

eg. Triclosan Listerine25-35% - plaque reduction

Mechanism of action : Act on cytoplasmic membrane inducing leakage of cellular constituents and thereby causing bacteriolysis.

74Triclosan is included in tooth paste to reduce plaque formation. Used along with Zinc citrate or co-polymer Gantrez to enhance its retention within the oral cavity. Delays plaque formation. It inhibits formation of prostaglandins & leukotrienes there by reduce the chance of inflammation.

75Quaternary ammonium compounds :

Eg. Benzathonuim chloride Benzalkonium chloride Acetyl pyridinium They are cationic, antiseptics & surface active agents. Side effects: burning sensation of oral mucosa brownish discoloration of teeth recurrent ulcerationdiscoloration of tongue

76Mechanism Of Action:

Positively charged molecule reacts with negatively charged cell membrane phosphates and thereby disrupts the bacterial cell wall structure of microorganisms.

77Sanguanarine (Natural products/ Herbal extracts)

It is benzophenanthradine alkaloid found in commercial mouth rinse paste. Mechanism of action: Inhibiting the growth of bacteria. pH is 4.5 and alcohol content of 11.5%78Metal salts Zinc Salts Tin Salts (Stannous fluoride) Sodium fluoride Copper salts Adverse effects Metallic taste Dryness of Mouth Yellow brown discoloration of teeth and tongue

Have a plaque inhibitory capacity as they reduce glycolytic activity in micro-organisms & delay bacterial growth.

79 2nd Generation Bisbiguanides: eg. Chlorhexidine gluconate 0.2 % Alexidine Cationic Chlorophenyl biguanide

Suggested for oral use by Schroder in 1969

pH 3.5 It is a cationic effective against gram +ve ,gram-ve, fungi, yeasts & viruses.

Its superior action is due to its property of sustain availability i.e. substantivity.

80Mechanism Action

It prevents pellicle formation. It prevents adsorption of bacterial cell wall on to the tooth surface. It prevents binding of mature plaque.

81Metabolism of Chlorhexidine Glauconate Bacteriostatic (Reversible effects )

Cationic Chlorhexidine molecule is attached towards negatively charged bacterial cell surface & it is adsorbed by phosphate containing compounds.

The cationic Chlorchexidine molecule added integrity of bacterial cell memb. enter into cell memb.

Permeability of inner memb will increases & there will be leakage of low molecular weight components.

Bactericidal (irreversible effects )

Increase concentration of chlorhexidine

Coagulation and precipitation of the cytoplasm by the formation of phosphated complexes, adenosine phosphate & nucleic acid.

82Properties:

Bacteriostatic at low conc.Bactericidal at high conc.It exhibits antibacterial activity for 5 hrs & supresses salivary bacterial count for over 12 hrs. after a single use. Plaque reduction upto 80-90%.Potent antifungal agent in oral cavity.

European Formula - 0.2% USA Formula - 0.12%

83Adverse effects (chlorhexidine)Brownish staining of teeth & restoration which is reversible. Has a bitter taste. Loss of taste sensation which is transient Painful desquamative lesions of the oral mucosa with burning sensation. Parotid swelling rarely cause side- effects Condition subside in a few days by discontinuing the mouth wash. Rarely hypersensitivity.

843rd Generation Delomopinol:-

Inhibits plaque growth reduce gingivitisIt interferes with plaque matrix formation & also reduces bacterial adherence. It is indicated as pre- brushing mouth rinse as it weakens binding of plaque to the tooth surface.

85Conclusion More than 500 bacterial strains have been identified in dental biofilm. Most forms of periodontal disease are caused by specific pathogens, particularly gram-negative bacteria. The recognition that dental plaque as a biofilm helps to explain why periodontal diseases have been so difficult to prevent and to treat. Periodontal pathogens within a biofilm environment behave very differently from free-floating bacteria. The protective extracellular slime matrix makes bacteria extremely resistant to antibiotics, antimicrobial agents, and host defense mechanisms. Mechanical removal is the most effective treatment currently available for the control of dental plaque biofilms.

86RefrencesCLINICAL PERIODONTOLOGY - CARRANZA ( 10th edition)

CLINICAL PERIODONTOLOGY AND IMPLANT DENTISTRY- LINDHE

ESSENTIALS OF PREVENTIVE AND COMMUNITY DENTISTRY- SOBEN PETER ( 3RD edition)

SHAH HN, COLLINS DM: PROPOSAL FOR RECLASSIFICATION OFBACTEROIDES ASACCHAROLYTICUS, BACTEROIDES GINGIVALIS, ANDBACTEROIDES ENDODONTALISIN A NEW GENUS,PORPHYROMONAS. INTERNATIONAL JOURNAL OF SYSTEMATIC BACTERIOLOGY 1988; 38(1):128-131.

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