Relation between commencement of menstruation and tooth development in ninety-one girls in a primary school in Kumamoto City who were in the 6th Grade in 1965 was studied, with resultsas follows:
1. In early cases, menstruation begins at 9 years and 11 months of age; menarche increases from about 11 years and occurs in large numbers during 11 years and 10 months and 12 years and 3 months. That is, 34.07% of the girls had the menses before they finish primary school.
2. Dental condition at the time of menarche was as follows:
a) In general three or more second molars had erupted before menarche. Its percentage was 77.41%. At least the bilateral second molars on the lower jaw had erupted before the first visit of the menses in all the case.
b) Presence of remaining deciduous teeth was investigated, with the result that 80.65% of the subjects had no deciduous teeth in their jaws. Even if there was any, it was supposed to be not more than one.
It was considered that, along with the growth in stature, degree of tooth development may be used as an indication of the time of menarche.
