Dental Plaque is defined as a BioFiolm of Structured Resilient Yellow Greyish substance that adheres to intra oral tooth surface or other hard surface in the oral cavity including removal and fixed restoration.
Maximum accumulation of Plaque takes place in 21 days. Dental Pellicle forms within seconds after brushing. Initial plaque formation takes as long as 2 hours to start forming.
- Few Seconds: Acquired pellicle formation and bacterial adhesion
- 2 Hours: Initial Plaque formation takes place. Irreversible colonization of Bacteria has taken place.
- 6 Hours: Supragingival Plaque is well established
- 2 Days: Plaque doubles in mass
- 5-7 days: Plaque maturation is dominated by filamentous bacteria
- 21 days: Bacterial replication slows so that plaque accumulation becomes relatively stable
- 12 weeks: Well differentiated subgingival plaque is formed, dominated by Gram Negative Bacteria
Pellicle formation takes place by selective adsorption of mainly salivary and microbial molecules to the tooth surface. Molecules like PRP, ammylase, mucins and statherin function as receptors for bacterial adhesion. Glucosyltransferases can also be found in the active form in the enamel where it synthesizes glucan that serves as a binding protein ligand on streptococci
Irreversible Bacterial adhesion results from a short range (1nm) stronger, specific stereochemical interactions involving bacterial surface components (adhesins) and cognate receptors on the pellicle. A common type of such interactions is what is called lectin like adhesion which involves binding of carbohydrate (glycosidic) receptors by bacteria polypeptide adhesins. Bindind of glucan by bacterial glucan binding protein is one example.
Cohesion (or) Co-aggregation: This is a very important stage where the adhesin-receptor interaction takes place between the approaching bacteria and the already attached colonized bacteria increasing the diversity of the bio film.