Erard E, Cannoni P, Deroze D
Orthod Fr. 1989;60 Pt 2:635-40.
Early extractions of first permanent molars, done on twenty cases without any orthodontic treatment, have not shown, following the Student's analysis, any statistical difference relative to a pilot group as far as the angles. SN- ANS- PNS, SN-OP, SN-GoGn, FMA, Y-axis are concerned. On the other hand, it has been revealed a closure of the angle ANS- Xi- MP associated with an opening of the mandibular arch.
对20例未接受任何正畸治疗的患者进行第一恒磨牙早期拔除，根据学生分析，就SN-ANS-PNS、SN-OP、SN-GoGn、FMA、Y轴等角度而言，与试验组相比未显示出任何统计学差异。另一方面，已发现ANS-Xi-MP角闭合，同时下颌弓张开。
