i. Enamel/Aquired pellicle
ii. Dental plaque
iii. Materia alba
iv. Calculus
i. AQUIRED PELLICLE: It is an amorphous organic and membraneous layer found on exposure tooth surfaces as well as restoration.
They are accellular,translucent,homogenous,thin,unstructured film covering and adherent to the tooth surface,and other form surfaces in the oral cavity. It is formed after tooth eruption from the protein of saliva.
NOTE: Dextran and levan are sticky substances produced by bacteria in the mouth and are aerobic.
ii. DENTAL PLAQUE: This is the first deposit after enamel pellicle formation. It is a dense non-calcified highly organised bacteria mass embedded in an inter bacteria matrix which adhere closely to the teeth,calculus and other hard surfaces in the oral cavity. It is resistant to the cleansing effect of saliva
The microorganism of dental plaque contributes in the development of dental caries and inflammatory of periodontal diseases. It consist of such salivary components as mucin and desquamated epithelial cells and of microorganisms.
COMPOSITION OF DENTAL PLAQUE
Plaque is compose of 70% bacteria and 30% inter bacteria substance. It includes extracellula polysaccharides and host cells.
SIGNIFICANCE OF PLAQUE IN DENTISTRY.
When plaque is exposed to cariogenic diet e.g refined carbohydrate, which produces acids that dissolves the enamel leading to dental caries in subsceptible individual.
In contact with the gums, the bacteria product irritates the gum resulting to gingivitis with progression to periodontitis if uncontrolled.
If left foq a long time in the mouth, it calcifies to form dental calculus which gives futher attachment and permanent to dental plaque.
iv.DENTAL CALCULUS: Calculus is a calcified plaque,which is formed when plaque stays in the mouth for a long time and will incoorporate enough mineral (calcium) to be calcified. The colour is off-white from yellow to dark brown or black(for smokers).
Calulus tends to start from buccal surface of the molar and the lingual surface of the anteriors because of the opening of the salvary gland, into the mouth.
TYPES OF CALCULUS.
The two types of calculus differs considerably in their clincal appearance and their distribution.
a. SUPRAGINGIVAL CALCULUS: Calculus is supragingival if it occurs above the gingival margin of the gum, on the surface of the enamel. It present at very concentration and most prevailant on the lower aspect of the incisor and molars.
b. SUBGINGIVAL CALCULUS: Occurs below the gum margin within periodontal pocket.its formed in a relatively small quantity.it has no pre-dilation of the mouth but where ever there is periodontal pocket.
NOTE: Calculus forms mainly on areas opposite the orifice of major salivary glands. It is compose mainly of calcium salt, i.e. Calcium phosphate and Calcium carbonate. The calcium salts are precipitated when saliva on secretion loses carbon dioxide and becomes more alkaline as the PH rises.saliva itself is saturated with hydroxyapatite and apatite crystals are precipitated by this process.
Dental caries is the decay and irreversible infection crmbling of the substances ov the tooth. It is caused by the metabolism of the bacteria in plaque attached to the tooth surfaces. The acid produce by the baterial breakdown of sugar in the diet causes demineralization of the enamel of the tooth. If no preventive measure is applied, it spreads into the dentine and progressively destroys the tooth.
It is the most common cause of toothach, and once infection has spread to the pulp it may extend through the root canal into the periapical tissues to cause an apical abscess.
Frequent intake of carbohydrat is a major cause, and the disease is more common in young people and has a predilation for specific sites in the oral cavity.
The two groups of bacteria responsible for initiating caries are:
1-strptococcus multans
2-lactobacillus.
Dental caries can be prevented effectively by restricting the frequency of sugar consumption and avoiding sweet food and drinks at bedtime.
Enamel resistance to dental caries can be increased by the application of fluoride salts to the tooth surface from tooth past/mouth rinse.
Fluoridation of water also makes teeth resistant to caries during the period of tooth development.
Once caries spreads into the dentine, treatment is usually consisting of either removing the decayed part of the tooth and replacing it with a filler
