3. Definition of Dental caries
Dental caries is defined as a preventable, chronic and biofilm mediated disease
modulated by diet. This multifactorial, infectious oral disease caused primarily
by complex interaction of cariogenic oral flora (Bio film) with fermentable
dietary carbohydrates on the tooth surface over time.
4. Etiology
Dental caries is a disease that is dependent on complex inter relationships between following
five critical parameters:
I. Biofilm
II. Tooth habitat
III. Diet
IV. Saliva
V. Oral hygiene
5.
6. I. Biofilm
• Plaque defined as a soft, unmineralized, biofilm consisting of a variety of
bacterial species embedded in a matrix derived from salivary mucins and
extracellular polysaccharide polymers synthesized by the organisms.
7. • Plaque formation proceeds through following stages
1. Deposition of a cell free layer, Acquired Pellicle which is derived from salivary glycoproteins.
This layer acts as nutrient for plaque bacteria.
2. Colonization of pellicle by Gram positive bacteria like S.sanguis and S.mutans within
24hours
3. Maturation of plaque by further colonization with filamentous and other bacteria. Also there
is build up of plaque substance by polysaccharides produced by plaque bacteria.
8.
9. II. Tooth
• Tooth habitats provides favourable environment for pathogesis of biofilm.
These are;
• Composition
• Morphological characteristics
• Position
10. III. Diet and caries
• Carbohydrates changes the ph of oral environment by changing the
composition of biofilm and producing the highly acidogenic environment.
• High frequency exposure to fermentable carbohydrates such as sucrose
• Sugar taking frequency in between the meal,
• Sugar containing acid beverages, increase the risk of caries.
11. Critical Ph
• The critical ph for enamel is 4.5-5.5
• The critical ph for dentin is 5
• Normal Ph 6.9 to 7.2
12. Stephan curve
• Stephan curve is a stimulated model shows how plaque reacts
to carbohydrates
• After sugar exposure, ph drops very rapidly to its critical value
5.5-5.2. Tooth is at risk.
• Repeated fall of ph leads to more and more mineral loss.
• After 30-60 minutes ph returns to its original value.
• If buffering action is not available, the plaque PH could drop
to 3 or 4
• Salivary buffers are ineffective at ph 5 or below 5.
13. IV. Saliva
Saliva is an extremely important substance for the proper digestion of foods,
and it also plays a key role as a natural anticaries agent.
• Bacterial Clearance
• Direct Antibacterial Activity
• Buffer Capacity
• Remineralization
14. Bacterial Clearance:
• Adults produce 1 to 1.5 L of saliva a day, very little of which occurs during
sleep.
• The flushing effect of this salivary flow is, by itself, adequate to remove
virtually all microorganisms not adherent to an oral surface. The flushing is
most effective during mastication or oral stimulation, both of which produce
large volumes of saliva.
• Large volumes of saliva also can dilute and buffer biofilm acids.
15. Direct Antibacterial Activity:
• Lysozyme, lactoperoxidase, lactoferrin, and agglutinins possess antibacterial activity.
• These salivary proteins are not part of the immune system but are part of an overall
protection scheme for mucous membranes that occurs in addition to immunologic control.
• Individuals with decreased salivary production (owing to illness, medication, or irradiation)
may have significantly higher caries susceptibility.
16. Buffer Capacity:
• The volume and buffering capacity of saliva available to tooth surfaces have major roles in dental
caries protection.
• The buffering capacity of saliva is determined primarily by the concentration of bicarbonate
ion.
• In addition to buffers, saliva contains molecules that contribute to increasing biofilm pH. These
include urea and sialin.
17. Remineralization:
• Saliva and biofilm fluid are supersaturated with calcium and phosphate ions.
• This supersaturated state of the saliva provides a constant opportunity for
remineralizing enamel and can help protect teeth in times of cariogenic challenges.
