第一小臼齒 拔去가 II級1類 不正咬合者의 顔貌와 齒列弓에 미치는 影響에 關한 硏究

A STUDY ON THE EFFECTS OF THE 1st BICUSPID EXTRACTION ON THE CHANGES IN FACE AND DENTAL ARCH FORM IN ANGLE CLASS II DIV.1 MALOCCLUSIONS

This study was undertaken to compare the main differences and its effects of the 4 first bicuspid extraction on the face and dental arch of the class II div 1 malocclusion. The subjects consisted of twenty two class II div 1 malocclusion, four males, eighteen females, were 14 Years 2 Months old at the start of the treatment 16 Year 3 Months old at the end of the treatment.(mean age) Twenty one variables were observed by comparing the statistical data of the pretreatment records with postteratment records, which were consited of eight varibles on the study model digitation, thirteen variables on the tracing of the lateral cephalogram. The following results were obtained. 1. No significant change was observed in the intercanine width. 2. Intercuspal widths of the 1st. premolar and 2nd. premolar were decreased. 3. Change of the overjet was dependant upon upper anterior rather than lower anterior. 4. No significant changes were observed in facial plane angle and ANB angle. 5. Uprighting of the lower 1st. molar had an effect on the increase of the facial height .