In order to study the influence of diet on the incidence and severity of carious lesions and changes of microfolra in the plaque, 271 hamsters in the weaning period were inoculated with
S. mutans (sero type d) orally and reared with a cariogenic diet (Diet 2000, CLEA Co., Japan).
First investigations the cariogenic diet (powder) were kneaded (clayish), hardened (pellet), heated (powder, plate and pellet) with adding water, moreover, heated pellet diet was repowdered. Then the incidence and severity of carious lesions on each of them were studied, and the relation of the size of sucrose particles and quantity of sucrose in the diet with the incidence and severity of the carious lesions was evaluated.
Next, quantitative microflora changes in the plaque were investigated, including
S. mutans, and ATP analyses were made.
The results were as follows:
1) The size of sucrose particles in the powdered cariogenic diet were closely related to the incidence and severity of carious lesions. 2) As far as the incidence and severity of carious lesions are concerned, the physical qualities of diet are altered by various treatments. Especially, the more the adhesive properties of the diet were increased, the more the craious lesions were observed. 3) As far as the nutritional value of the diet, diminished by heating, are concerned, the influence on carious lesions was much less than the influence on the nutritional needs of the entire body system. 4) The incidence and severity of carious lesions did not depend upon the quantity of sucrose in the diet, when it was fed in pellet form (kneaded, hardened and heated). 5) The maxirnam stationary phase of
S. mutans was prolonged by adding 5 % sucrose to Tripticase Soy Broth (BBL). 6) After 28 days,
S. mutans was made up more than 80 % of the microflora in the hamster plaque. 7) The total number of microorganisms and
S. mutans in the experimental groups was significantly increased, compared to the control groups. 8) The ATP studies were very useful in analysing the cariogenic plaque. 9) It is necessary to define the physical qualities of cariogenic diet in experimental studies.
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