LONGITUDINAL DATA ON ERUPTION AND ATTACK OF THE PERMANENT TEETH

¹ U. S. Department of Health, Education and Welfare, Social Security Administration, Children's Bureau, Washington, D. C.

1. Methods for analyzing longitudinal records of dental conditions are described.

2. Application of the methods to serial data on 100 Cleveland school children confirms the existence of considerable departures from straight-line development in the age curves for total teeth erupted and total teeth attacked. Although no such departures were found in the curves of about one fifth of the children, in three fifths of the cases there were moderate departures, and in the remaining fifth the departures were marked. The material suggests that age data on eruption and attack obtained from cross-sectional studies tend to mask the extent to which plateaus exist in individual children. Study of the median eruption ages of the fourteen tooth pairs confirms the belief that the reason for the plateaus is the marked batching of the teeth in respect to eruption age.

3. Of all attacked permanent teeth, about 86 per cent are accounted for by attacked first molars at age 10 years.

4. Effectiveness of treatment has been studied by analyzing the data on 266 first molars attacked by age 10 years, among which 121 had been treated and 145 had not. Of the treated teeth, only 17 per cent were lost during the period covered by the records. Of the untreated teeth 88 per cent were lost, and the distribution of their survival times indicated that most of the remaining 12 per cent would have been reported lost a few years later if the children had been followed longer.