Abstract
On the basis of the dental health examination of 799 infants (414 boys and 385 girls)at the age of 1 year and 6 months±2 weeks and the questionnaires to their mothers, factors contributing to the dental caries of the early period were sought. The oral examinations of infants included noting the incidence of dental caries, oral hygiene conditions, numbers of erupting teeth, pH value of Cariostat, height and weight. As for their mothers, the pH value of Cariostat was evaluated as well as the questionnaires concerning nursing methods, dietary habits, tooth brushing habits, and other technical dental phenomena which might be familiar to mothers.
Discriminant analysis was carried out by subjecting them to the second class of Hayashi's quantifying theory. Presence or absence of the dental caries in infants was chosen as an external criterion.
As a result, contributing factors which separated the infants with dental caries from the subject without caries at the age of 1 year and 6 months were found to be as follows: the oral hygiene factor, the developmental factor and the oral habit factor. It was suggested that these factors might be the most important item when oral hygiene instructions for the child are given at such an early period.
