[Relationship between late adolescent growth of mandible and maturity indicators--mandibular third molar, hand bones, body height--in Japanese boys].

The study was undertaken to investigate the individual growth timing of the mandible during late adolescent period. Materials used in this study were lateral cephalometric X-rays, hand bones X-rays, panorama X-rays and data of standing height of eighteen Skeletal Class I Japanese boys, all were longitudinally taken from 15 to 18 years old. Results were as follows: 1. Mandibular growth was continued to increase until 18 years old, but annual growth rate was decreased every year. 2. Growth increments of mandibular length was widely varied during 15 to 18 years old. 3. Ossification timing of MP3u and R-IJ stage were tended to delay in cases, represented large amount of growth. 4. Cases showing large amount of growth in the mandible tended to have large increments in body height. 5. There was less correlation between mandibular growth timing and maturation of lower third molars. In conclusion, the growth behavior of hand bones and body height could be used as indicators for predicting mandibular growth potentiality during late adolescent period.