不同前磨牙拔除模式对安氏Ⅰ类病例软硬组织B点的影响

摘要] 目的：通过不同拔牙模式研究安氏I类错牙合患者治疗前后软硬组织B点变化的影响。方法：本研究选择50例安氏Ⅰ类临界病例，包括拔除第一前磨牙组和第二前磨牙组各25例。分别测量14项矫治前后头颅侧位片的软硬组织指标。组内和组间比较采用T检验。结果：(1)矫治前，两组患者在水平和垂直距离差异没有统计学意义；矫治后，各点垂直方向上的变化在拔除第一前磨牙组中存在显著差别(P<0.05)，而软硬组织B点水平方向上的变化在拔除第二前磨牙组中相对明显。（2）硬组织变化方面，治疗前两组患者差异无统计学意义；治疗后，两组患者下切牙轴倾度、SNB角变化无统计学意义，NB的线距减少且差异有统计学意义(P<0.01 )；拔除第一前磨牙和第二前磨牙组间差异无统计学意义。（3）软组织变化方面，治疗前，两组患者的下唇倾角、下唇翻卷度和B'-EP差异无统计学意义，但颏沟倾角差异有显著的统计学意义( P<0.001)；治疗后，两组患者软组织显著改善；矫治前后两组间差异无统计学意义。结论：正畸拔牙矫治显著改变软、硬组织B点，但两种不同拔牙模式间对软硬组织的改变没有统计学意义。

Skeletal and soft tissue point B changes with different premolar extraction patterns

Objective To compare skeletal and soft tissue point B changes in Class I malocclusion patients by difference extraction models. Methods The pretreatment and posttreatment records of 50 patients were used in the study. 25 patients involved extraction of first premolars and 25 patients involved extraction of second premolars. The lateral cephalometric radiographs taken before and after treatment were traced and measured. 14 typical values were measured in Winceph 7.0 software and statistical analysis was carried out by SpsslT. 0 software with t test. Results （ 1 ） The horizontal and vertical lines were not significantly different between the two extrac- tion groups before the treatment. But the vertical changes of skeletal and soft tissue point B were more apparent in the first premolar ex- traction group after the treatment. And the horizontal change of soft tissue point B was apparent in the second premolar extraction group. （2） In the hard tissue measurements, all the values were not significantly different between the two extraction groups before the treat- ment. After the treatment all the patients had a significant decrease in incisal inclination and length of L1-NB. significantly different be- tween the two premolar extraction groups. （3） In the soft tissue measurements, the values of 〈 B＇-LL-FH and 〈 Pos-B＇-FH in the first extraction group were less than those in the second extraction group before the treatment. After the treatment, all the patients had a sig- nificant improvement in soft tissue profile. And all the changes were not significantly different between the two premolar extraction groups. Conclusions The skeletal and soft tissue point B both changed remarkably after the extraction orthodontic treatment. There was no significant difference between the two premolar extraction groups.