3/8/2022 Dental plaque Enamel pellicle Enamel pellicle = an amorphous layer of saliva glycoproteins bound on the surface of enamel Negative charge of saliva glycoproteins (PRP, histidine-rich proteins, MG1) Positive ions of enamel (some involved Ca ions) Bind Develop Prof. Wihas Sosroseno Layer called “pellicle” (1/3 is PRP) More sticky on the enamel Faculty of Dentistry AIMST University PRP denatured Inhibit MG1 accumulation Glycolipid and PRP inhibit MG1 deposition Arrows= pellicle stained with disclosing solution Components of pellicles act as specific receptors for bacterial binding MG1 Bacteria Alpha-amylase and salivary cystatin SA1 or MG1 and sIgA bind cooperatively Initial dental plaque development Enamel pellicle During development of pellicle, each of saliva glycoproteins may inhibit or facilitate each other sIgA Lysozyme Supragingival plaque Chemical composition of dental plaque Dental plaque contains 80% water, protein, carbohydrate and inorganic ions (e.g., Ca, P, and F) Dental plaque matrix contains proteins originated from saliva and bacteria Saliva proteins pH changes Protein denaturation Sialic acid cleavage Dental plaque fluid Dental plaque fluid represents actual chemical phase in equilibrium with tooth surface, suggesting that diffusion of components through the plaque is relatively free Proteins and carbohydrate between the cells or on the enamel surface are not a barrier Protein accumulation in plaque Protein less soluble Ca ion Proteins Carbohydrate Enamel Dental plaque 1 3/8/2022 Composition of dental plaque fluid Plaque fluid contains inorganic ions, proteins, carbohydrate, amino acids, ammonia, hydrogen carbonate High levels of potassium – may be due to cell damage following centrifugation or may reflect of the number of bacterial cell death or leaky of bacterial cell wall in the plaque High levels of calcium and phosphorus (with the highest levels in the plaque of lower anterior teeth) – due to solubility of hydroxyapatite Concentration of calcium and phosphorus – increase with age of plaque Metabolic activities of dental plaque Chemical composition of dental plaque Mono- or polysaccharides (from diet) Bacterial metabolism Acid Glycogen (from bacterial intracellular store) Lactic acid Acetic acid Formic acid Butyric acid Proprionic acid In plaque fluid: highest levels - acetic and proprionic acid The levels of butyric and formic acid higher than lactic acid Stephan curve: after sugar intake, dental pH falls rapidly rises slowly back to the original pH about 20-30 minutes Lowest dental plaque pH depends on: Diffusion of sugar in the dental plaque Diffusion of hydrogen ions outward Dental plaque buffering Buffering capacity of dental plaque (largely due to phosphate buffering) > that of saliva The critical dental plaque pH = 6.4-5.0. If pH below this value, the enamel dissolution would be initiated Production of alkali in dental plaque Urea Dental plaque Plaque proteins ammonia pH rise Produce Protease Amino acid Arginine or sialin (arginine residue) Polysaccharide synthesis in dental plaque Characteristic of bacterial plaque metabolism – synthesis of carbohydrate polymers from the simpler sugars Intracellular bacterial storage of glucosa (glycogen): Glycogen The alkali production by dental plaque – mainly occur during “carbohydrate starvation” (e.g., overnight) Storage For next metabolism 2 3/8/2022 Carbohydrate polymer synthesis Streptococcus mutans Glucosyl transferase Important of dental plaque metabolism in health Proteolytic enzymes (e.g, Glucan/dextran collagenases, elastase) (glucose polymer) (alpha-6 bond) Sucrose Adhesive materials for bacterial adherence Deposit extracellularly Produce Dental plaque Calculus formation Breaking down inorganic phosphate & releasing Ca from proteins Fructan/levan Glucosyl transferase (Fructose polymer) (beta-1,2 bond) Dental calculus Dental plaque Increased Ca and P deposit 3 days No decalfication of enamel occurs Hydroxyapatite Amorpous calcium (no apatite formation) (seen in lingual surface of lower incisor) Homogenous crystalization (due to Possible pathway of early calcification of dental plaque Salivary glycoproteins Nucleating substances Bacterial proteolytic enzymes of dental plaque Maintain Ca ion levels increased Ca & P) (seen as random spicules of calcium phosphate) Dental calculus extends to root apex Possible involvement of bacteria in dental plaque calcification by raising local pH due to urease activity by increasing local ion concentration by splitting calcium-binding proteins by removing local inhibitors of calcification, e.g., phyrophosphate Some bacteria, e.g., Corynebacter matruchorii, Actinomyces israeli & Strepcoccus salivarius calcify themselves intracellularly Tissue damage Exotoxins (enzymes) Split calcium-binding proteins Release Ca ion to dental plaque Early calcification of dental plaque in an extracellular enviroment Accumulate Ca ion to dental plaque Crystal growth Intracellular calcification of C. mantruchotii Calcium & phosphate C. mantruchotii Early crystal = brushite metamorphose High energy metabolites Proteolipids (10.000 kD proteolipid & acidic proteolipid) Alkaline phosphatase Poorly crystalline apatite 3 3/8/2022 Two types of dental calculus Supragingival calculus: yellow or white Subgingival calculus: dark brown or greenish Save the earth !! Differences between supra- and subgingival calculus: Subgingival calculus: anaerob bacteria Thank you Subgingival calculus: seeded by gingival fluid/plasma Different nature of cementum and dentine surfaces and frequency of bleeding in gingival crevice 4
