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Dental plaque

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INTRODUCTION <ul><li>1 mm 3 of dental plaque, weighing about 1 mg contains more than 200 million bacteria </li></ul>

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Index <ul><li>Definition </li></ul><ul><li>Classification </li></ul><ul><li>Composition </li></ul><ul><li>Clinical feature </li></ul><ul><li>Formation </li></ul><ul><li>Clinical significance </li></ul><ul><li>Diagnosis & treatment </li></ul><ul><li>Conclusion </li></ul><ul><li>References </li></ul>

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Definition <ul><li>IT IS A MICROBIAL ECOSYSTEM OR BIOFILM COMPOSED OF DENSELY PACKED MICROBIAL STRUCTURE INSOLUBLE SALIVARYGLYCOPROTEIN , MICROBIAL INTRACELLULAR PRODUCT & TO SOME EXTENT EPITHELIAL CELLS & DEBRIES ARRANGED IN AN ORGANISED COMPLEX INTER CELLULAR MATRIX. </li></ul><ul><li>- BY WHO </li></ul>

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<ul><li>by location on tooth </li></ul><ul><li>supra gingival plaque sub gingival plaque </li></ul><ul><li>coronal marginal attached unattached </li></ul><ul><li>tooth asso. tissue asso. </li></ul>CLASSIFICATION

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<ul><li>By pathogenic effects </li></ul><ul><li>Cariogenic periodontal ds’ calculogenic </li></ul><ul><li>plaque producing plaque plaque </li></ul>

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<ul><li>PRIMARILY OF MICRO-ORGANISMS </li></ul><ul><li>Gram +ve - </li></ul><ul><li>s.mutans </li></ul><ul><li>s.Sanguis </li></ul><ul><li>s.Milleri </li></ul><ul><li>s.Salivarius </li></ul><ul><li>Gram –ve - </li></ul><ul><li>a.Viscosus </li></ul><ul><li>a.Naslundi </li></ul><ul><li>a.Israelli </li></ul><ul><li>Gram –ve anaerobic cocci – </li></ul><ul><li>Vellionellae </li></ul><ul><li>v.parvula </li></ul>COMPOSITION

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<ul><li>Organic : - </li></ul><ul><li>Polysaccharide </li></ul><ul><li>Protein </li></ul><ul><li>Glycoprotein </li></ul><ul><li>Lipid </li></ul><ul><li>Albumin </li></ul><ul><li>Inorganic : - </li></ul><ul><li>Phosphorous </li></ul><ul><li>Sodium </li></ul><ul><li>Pottasium </li></ul><ul><li>Fluoride </li></ul><ul><li>calculus </li></ul>

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PLAQUE MICRO-ORGANISMS <ul><li>DAY :- 1-2 </li></ul><ul><li>Early plaque is consisted of streptococci which dominates bacterial population include, s. mutans, s.sanguis </li></ul><ul><li>Day :- 2-4 </li></ul><ul><li>cocci r still dominate & increase in no of filamentous may be seen. gradually filamentous form grows into cocci layer & replace them. </li></ul>

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<ul><li>Day : - 6-10 </li></ul><ul><li>filamentous increase in no.along with rods, spirilia, & fusobacteria. </li></ul><ul><li>Plaque near the gingival margin is thicker & develops more mature flora earlier with spirochete & vibrios </li></ul><ul><li>As plaque matures- more gram –ve & anaerobic organism appear. During the period when this is happening, signs of inflmmation begin to observe in the gingiva. </li></ul><ul><li>Older plaque :- spirochete & vibrios r prevalent along with cocci & filamentous m.o arranged themselves perpendicular to the tooth surface in a palisade </li></ul>

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<ul><li>DENTAL PLAQUE IS A MICROBIAL BIOFILM. </li></ul><ul><li>Biofilms – “ defined as matrix enclosed bacterial populations adherent to each other and/or to surfaces or interfaces.” </li></ul><ul><li>( costerton,1994 ) </li></ul>FORMATION

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<ul><li>Biofilm can be formed by a single bacterial species or multiple bacterial species as well as other organisms & debris. </li></ul><ul><li>It can form on any surfaces that is wet. </li></ul><ul><li>It can exist on any solid surfaces that is exposed to bacteria-containing fluid. </li></ul>

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Biofilm structure <ul><li>The bacteria in a biofilm r not distributed evenly, they cluster to gether to form sessile mushroom shaped microcolonies. </li></ul><ul><li>Each microcolony is an independent community with its own customised living environment. </li></ul>

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<ul><li>A protective extra cellular slime layer surrounds the microcolonies. </li></ul><ul><li>A series of fluid channels penetrate the slime layer & facilitate the movement of nutrients & bacterial products throughout the biofilm </li></ul><ul><li>A primitive communication system of chemical signals allows communication bt. the bacterial microcolonies. </li></ul>

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<ul><li>Bacteria 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. </li></ul>

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<ul><li>Fluid channels provide nutrients & oxygen for the bacterial microcolonies, waste products & enzymes within the biofilm structure </li></ul>

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<ul><li>The bacterial microcolonies use “chemical signals” to communicate with each other. </li></ul>

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<ul><li>Bacterial microcolonies r protected by one another or by extracellular slime layer & r usually resistant to antibiotics & antimicrobials, & the body’s defense system. </li></ul><ul><li>Can be destroyed by simply wipping off them. </li></ul>

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FORMATION OF DENTAL PLAQUE BOIFILMS <ul><li>THE PATTERN OF PLAQUE BIOFILM CAN BE DIVIDED INTO 3 PHASES : </li></ul><ul><li>Attchment of bacteria to the solid surface </li></ul><ul><li>Formation of microcolonies on the surface </li></ul><ul><li>Formation of the mature subgingival plaque biofilms </li></ul>

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1.Initial attachment of bacteria <ul><li>Pellicle formation – </li></ul><ul><li>defined as “an acellular layer of salivary proteins & other macromolecules, aproximately 2 to 10 micrometer thick, adsorbed on to the enamel surface.” </li></ul><ul><li>It has important role in protecting the enamel from abrasion and attrition but it also serves as diffusion barrier. </li></ul>

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<ul><li>A thin, bacteria free layer forms within minutes on a cleaned tooth surface. </li></ul>

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<ul><li>The purpose is to protect the enamel from acidic activity. </li></ul><ul><li>Acts like a double sided adhesive tape with their amino- terminal segments to the tooth surface,leaving their carboxy-terminal regions directed towards the oral cavity,where they may interact with oral micro-organisms </li></ul>

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<ul><li>Initial colonization of the tooth surface : </li></ul><ul><li>within few hours bacteria connect to the pellicle & each other with hundreds of hair like structures called fimbriae. </li></ul><ul><li>Stimulate other free floating bacteria to join the community </li></ul>

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<ul><li>4 hrs. after cleaning, there r 103 to 104 bacteria / 1 mm 2 of tooth surface,predominently streptococci & actinomycetes. </li></ul><ul><li>Within a day a no. of bacteria increases, due to growth of streptococci </li></ul><ul><li>The initial bacteria r called “pioneer bacteria” </li></ul><ul><li>It is interection bt. Pr. Adhesion on the surface of colonizing bacteria & carbo. Receptor on the salivary components adsorbed to the tooth surface. </li></ul>

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<ul><li>If within 2 days no further cleaning is undertaken, the tooth surface is colonized predominantly by gram +ve facultative cocci, which r primarily streptococci. </li></ul><ul><li>Extra cellular slime layer formation : </li></ul><ul><li>The act of attaching to the solid surface stimulate the bacteria to excrete a slimy glue like substance that helps to anchor them to the surface & provides protection for attached bacteria </li></ul>

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2.Microcolony formation <ul><li>Bacterial growth :- </li></ul><ul><li>primarily through cell division of the adherent bacteria(rather than attachment of new bacteria) </li></ul><ul><li>Next proliferating bacteria begin to grow away from the tooth. </li></ul><ul><li>Plaque doubling time are rapid in early development & slow in more mature biofilms. </li></ul><ul><li>Bacterial blooms - r periods when specific species or grp. Of species grow at rapidly accelerated rate </li></ul>

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Coaggregation into mushroom shaped microcolonies <ul><li>It is ability of new bacterial colonizer to adheres to previously attached cells </li></ul><ul><li>Forms sessile, mushroom shaped microcolonies that r attached to tooth surface at a narrow base & gives “corn cob” appearance or “taste tube brushes.” </li></ul>

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<ul><li>Central rod shaped bacterium becomes surrounded by many round cocci </li></ul><ul><li>“ bristles” of taste tube brush formation r composed of gram –ve rods. </li></ul>

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3. Formation of mature subgingival plaque biofilm

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<ul><li>Sub gingival plaque biofilm </li></ul>

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<ul><li>Relationship of plaque biofilm to alveolar bone </li></ul><ul><li>The distance bt. Apical edge of calculus & crest of alveolar bone in human pd pocket is constant, having mean length of 1.97 mm. </li></ul><ul><li>(indicates that bacteria r capable of producing bone resorbing activity only in alv. Bone no further than 2.7mm away from biofilm. </li></ul>

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Microbial interactions

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<ul><li>Although bacteria initiate the periodontal disease process, it is the body’s own immune response that is actually responsible for the breakdown of periodontal tissues. </li></ul><ul><li>Immune system complex in periodontitis </li></ul><ul><li>Phagocytes ( the army ) </li></ul><ul><li>Lymphocytes ( the air force ) </li></ul><ul><li>The complement system ( the navy ) </li></ul>

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Neutrophil

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<ul><li>Macrophage </li></ul>

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Lymphocyte

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Complementary system <ul><li>3 major function </li></ul><ul><li>Recruitment of phagocytic cells </li></ul><ul><li>Facilitation of phagocytosis by opsonization </li></ul><ul><li>Direct killing of bacteria by puncturing the bacterial cell membrane </li></ul>

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Phagocytosis

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Sequence of events in host response

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<ul><li>Early bacterial accumulation phase </li></ul>

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<ul><li>Plaque over growth phase : acute inflammation </li></ul>

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<ul><li>Sub gingival plaque phase </li></ul>

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<ul><li>Tissue destruction phase </li></ul>

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<ul><li>Tissue destruction in periodontitis </li></ul>

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<ul><li>Direct vision : - </li></ul><ul><li>Thin plaque – may be translucent & therefore not visible </li></ul><ul><li>Stained plaque – may be acquired </li></ul><ul><li>e.g tobacco stained </li></ul><ul><li>Thick plaque – tooth may appear dull & durty </li></ul>DETECTION OF PLAQUE

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<ul><li>USE OF EXPLORER : - </li></ul><ul><li>Tactile Examination – when calcification has started it appears slightly rough, otherwise it may feel slippery due to coating of soft , slimy plaque </li></ul><ul><li>Removal Of Plaque – when 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. </li></ul><ul><li>Use of disclosing solutions - </li></ul>

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<ul><li>SUPRA GINGIVAL PLAQUE </li></ul><ul><li>Occlusal surface leads to caries </li></ul><ul><li>Gingivitis </li></ul><ul><li>SUB GINGIVAL PLAQUE </li></ul><ul><li>Periodontitis </li></ul><ul><li>Other periodontal disease </li></ul>CLINICAL SIGNIFICANCE

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Treatment <ul><li>Several investigations r being carried out to develop plaque inhibiting agents which could be applied as mouth rinse, tooth paste,& chewing gums. </li></ul><ul><li>They interfere in plaque formation by </li></ul><ul><li>Prevention of plaque formation or alteration of plaque microflora by anti microbial substance </li></ul><ul><li>Prevention or absorption of organic matrix of the teeth </li></ul><ul><li>By means of enzymes capable of decomposing the inter microbial substance </li></ul>

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Surface treatment <ul><li>Chemical plaque inhibition is very little successful </li></ul><ul><li>Antibiotics </li></ul><ul><li>Other antimicrobial substance like chemical disinfectant </li></ul><ul><li>Chlorhexidine longer time use is not preferable because it causes discoloration of mucus membrane </li></ul>

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CONCLUSION PLAQUE + TIME = GINGIVITIS GINGIVITIS +TIME = PERIODONTITIS PERIODONTITIS + TIME = TOOTH LOSS

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REFERENCES <ul><li>FOUNDATION OF PERIODONTICS </li></ul><ul><li>- By donald E. willmann </li></ul><ul><li>DIAGNOSIS & RISK PREDICTION OF PERIODONTAL DISEASE </li></ul><ul><li>- per axelson,dds,odont dr </li></ul><ul><li>CLINICAL PERIODONTOLOGY </li></ul><ul><li>- caranza ( 9 th edition) </li></ul>