1. Dental Caries

2. Definition
Caries is a disease resulting in the destruction of the hard structure of the teeth

3. Stages in the development of caries
The enamel becomes decalcified
A small white spot appear
Discoloration becomes pronounced
The tooth surface softens and decay penetrates through the enamel into the dentine
Caries spreads laterally and in depth
Cavitation occurs

4. The lesion deepens, and pulp becomes affected, first reacting to stimuli (e.g.sweets, temp.), then damaged and dead
Bacteria travels down the root canal, out through the apex causing abscesses
Hanadi Baeissa

5. Factors determining the incidence of caries
Micro organisms: Acid producing bacteria, especially if they produce extracellular polysaccharides, will increase risk
Host factors:
Decreased saliva secretion increase incidence
Buffering power of saliva to raise pH decrease incidence
Hanadi Baeissa

6. The morphology of the teeth: well spaced teeth decrease incidence, while fissures & pits increase it.
The composition of the teeth: certain trace elements decrease incidence (e.g. F, Mb and B), while others (e.g. Cu & Mn) increase it
Hanadi Baeissa

7. Time: frequency of consumption of carbohydrates, and length of time in the mouth are related to incidence. Good oral hygiene can counter act this
Substrates for acid production provided in diet

9. Caries as a disease of civilization
Evidence links caries to civilization
This is due mainly to changes in dietary habits, e.g. increased carbohydrates intake by Eskimos and eating refined instead of natural forms of carbohydrates by African tribes

10. Factors in unrefined food lead to decreased incidence of caries
Substances that decrease solubility of calcium phosphate
More phytate &/or calcium
Antibacterial substances
Substances that inhibit aggregation of bacteria :- decrease plaque formation
Absence of free sugar (most important)

11. Theories for the cause of caries
The proteolytic theory: presence of proteolytic bacteria lead to hydrolysis of protein (collagen) leading to progression of caries
The phospho protein theory: phospho protein phosphatse in plaque acts on phosphoproteins in enamel, but this is not tested in humans

12. The proteolysis-chelation theory: some products of bacterial action on enamel, dentine, saliva & food constituents form complexes with calcium from plaque causing a decrease in the concentration required to maintain saturation, and leading to more solubility

14. The acid theory of caries: Bacteria in saliva + carbohydrate (sugar) lead to acid production dissolving appetite
This the most likely theory

15. Evidence In thick plaque, pH below critical point
pH in carious cavities is lower
Caries intensity correlates with acid production and count of acid producing bacteria
In germ-free rats, caries was produced by inoculation with acid producing organisms

16. The importance of diffusion:
Since caries is a penetrating lesion, the inward diffusion of the acid must play an important role in its development
Evidence shows that the concentration of unionized lactic acid outside the enamel is more important than low pH

17. Unionized acid diffuses more easily inward, becomes diluted and ionized, allowing reaction with apatite to form free calcium and phosphate
These ions diffuse outwards, and may precipitate as CaHPO4, explaining the apparently intact outer layer of enamel over the cavity
Therefore, the critical pH may not only be the level at which the environment of enamel becomes unsaturated with apatite, but it also maybe the pH at which sufficient conc. Of unionized lactic acid exists to ensure inward diffusion

18. The bacteria responsible for caries
Two species were isolated from carious mouths and were suggested as causal organisms:
Streptococcus mutants, and
Lactobacillus acidophilus or odontolyticus
Other filamentous bacteria producing lactic acid were isolated from caries lesions of the root surfaces. These bacteria, the genus Actinomyces are of two species
Actinomyces viscosus
Actinomyces naeslundi , both are found predominantly in the gingival region and cause; inaddition; severe periodontal disease

19. Relationship between lactobacilli and streptococcus mutans
streptococcus mutans alone can produce caries, but the combination is more effective
streptococcus mutans stop acid production at pH 4.3, but lactobacilli continue to below pH 4
Therefore, the joint effect is more intense
Lactobacilli seems to be involved in the initial attack, and is found at tha front of the lesion

20. Local effects in caries
Caries is localized, indicating the role of local conditions
This might be partly due to differences in composition of plaque (bacterial and matrix)
Evidence also suggests that different types of bacteria cause caries at different sites (e.g. tetracycline reduces smooth surface caries, to a greater extent than pit and fissure caries

21. The role of diet in caries
Diet has two types of effects
Dietary effects: local effects contributing to substrates for bacterial growth & direct interaction with teeth
Nutritional effects: effects of assimilated food stuff

22. 1.Dietary effects
There is evidence relating consumption of carbohydrates (particularly sucrose) to caries

23. A- Indirect Evidence for importance of dietary carbohydrates in caries
Eskimos, whose diet was formerly almost exclusively of fish, meat and fat, had a low incidence of dental caries while on their primitive diet
The prevalence of dental caries in different countries parallels the extent of sugar consumption in those countries

24. In many areas of Europe where sucrose intake was severely restricted during World War II, caries incidence in children decreased dramatically
The study of human biochemical genetics has also provided evidence that sucrose plays a special role in caries. A rare enzyme deficiency involving a lack of fructose-I-phosphate aldolase results in hereditary fructose intolerance. Foods containing fructose cause nausea, vomiting, tremors, and convulsions in affected individuals. As sucrose is a glucose-fructose disaccharide, it also produces these effects, and is avoided by such pateints, who are often found to be caries-free or else have a very low caries prevalence

25. Amongst present-day children of pre-school age there is a marked correlation between caries experience and the extent of eating between main meals
Rampant caries, in which the anterior teeth may be almost completely dissolved away, is found in babies who are given comforters filled with syrup or honey to suck for prolonged periods of time

26. B- Populations on controlled diets
The caries score (decayed, missing and filled teeth, DMFT) was followed over years for different groups given carbohydrates sources of increasing degree of stickiness compared to a control group given a diet low in carbohydrates, with the calories supplied by sugar normally , replaced by margarine

27. Hanadi Baeissa

28. A study conducted at an orphanage, indicated that refined carbohydrates increase the caries score. While resident, the children were given a diet that excluded refined carbohydrates , and had low caries score (DMFT), but this increased dramatically after they left and changed their diet to include sugar and refined carbohydrates

29. Interaction between carbohydrates & dental plaque
Epidemiological evidence & experimental studies indicated the following:
Carbohydrate free diet thin plaque
Presence of sucrose more plaque (gelatinous)
Sucrose is more cariogenic than glucose or fructose with respect to smooth surfaces

30. 4. Extra cellular polysaccharides are produced by bacteria from sucrose this help in:
Adherence to smooth surface
Retain acid in close proximity to tooth surface
Shield against buffering by saliva
The above are less important in fissures

31. Other dietary effects
Addition of Calcium sucrose phosphate (CaSP) caries
Acidic drink could dissolve enamel caries incidence
Fibrous food reduce plaque formation , therfore, caries
Foods that saliva flow caries e.g. salty foods
Foods that pH & increase Ca content caries e.g. cheese

32. 2- Nutritional effects Vitamin D could lead to incidence of caries
Some trace elements caries & some it

33. Minerals associated with increased caries include: Copper, magnesium, Se, zinc, vanadium & lead
Minerals associated with decreased caries include :
F, Sr, B, K, nickel, Mo, Li
Mechanism: suggestion
Effect morphology of teeth (rats)
Effect crystal structure & solubility

34. Caries resistance
Many factors not strong by themselves combine to caries e.g.
Highly buffered saliva with high flow rate
Ca, P, HCO3 in saliva
High F/CO3 of enamel
The most important factor is the type of bacteria
presence of antibodies to cariogenic bacteria might help to caries also

35. Finally the morphology of teeth plays a role
Note:
Cause of caries differs from person to another

36. Remineralization
Carious lesions up to white spot stage can cease to develop and might disappear
Caries progresses by alternate demineralization, when pH falls, and partial remineralization when the pH rises
Saliva could remineralization, but F speeds process