하악각과 하악 제2대구치에 대한 하악 제3대구치의 발육위치에 관한 연구

A study on the developmental position of lower third molar in relation to gonial angle and lower second molar

The aspects examined in the present study concerning the location and position of the lower third molar and the interrelationships of this molar, the gonial angle, and the second lower molar in subjects aged 8-24 are based on measureaments made from 472 orthopantomograms. The following conclusion were drawn on the basis of the present study. 1. The gonial angle decreased with age, but slight enlarging occurred in the age group 20-21. 2. The angulation of the third molar in relation to the second molar did correlate with the size of the gonial angle but decreased with developmental stage. 3. The mesial angle between the longitudunal axis of the second molar and the mandibular base line correlated significantly with the gonial angle. the above angle were smaller in Class II, Divison 2 and larger in Class III than in Class I and Class II, Division 1. 4. The rate of presence of third molar was 74.4%.