Abstract
On the basis of the dental health examination of 361 infants at the age of 18months and the questionnaires to their mothers, we sought out the factors associated with dental caries at the age of 3. The caries activity tests were conducted on the infants and their mothers, using the pH value of Cariostat, estimated colonies of S. mutans in saliva grown in MSB broth and the charactersistic color reaction of RD test correlated with the number of S. mutans and Lactobacilli in saliva at the same time.
Statistical analysis was carried out by subjecting those items with the use of the second class of Hayashi's quantifying theory, in which the existence of decayed or filled teeth for each infant was chosen as external criteria. Furthermore, in order to predict the cariogenecity at 3 years of age from 18 months, the df-s index at the age of 3 was used by applying the first class of Hayashi's theory.
As a result, the main factors contributing to the existence of dental caries at 18 months were found to be the pH value of the Cariostat and MSBB in infants, the condition of the oral hygiene and the tooth brushing habit. On the other hand the factor contributing the most to dental caries at the age of 3 was found to be the result of MSBB in the infants, followed by pH value of Cariostat in mothers and habit concerning meal snacks. It was suggested that these factors might be the most important items when we try to pick out the high risk patient for dental caries at the early stages.
