不同前磨牙拔除模式对颏部软组织变化的影响

Soft tissue changes of chin with different premolar extraction patterns

目的:对拔除第一前磨牙和拔除第二前磨牙的安氏I类错患者治疗前、后颏部软组织变化进行比较,探讨2种拔牙模式的异同。方法:患者50例,均为安氏Ⅰ类错畸形,分为2组,每组25例,分别拔除4颗第一前磨牙和4颗第二前磨牙进行治疗。2组患者按性别、年龄、骨面型、拥挤度严格配对,对治疗前、后的头颅侧位X线片颏部软组织指标进行测量比较,采用SPSS10.0软件包对数据进行t检验。结果:(1)在相对X、Y轴的绝对值测量中,治疗前2组无任何统计学差异;治疗后第一前磨牙拔除组在垂直方向上增长明显,而第二前磨牙拔除组在水平、垂直方向上均有增加,水平向生长更明显。(2)在对软组织项目的测量中,治疗前第一前磨牙拔除组的软组织面角、颏沟倾角均小于第二前磨牙拔除组,治疗后2组均出现软组织面凸角减少,颏凸角、软组织面角、颏沟倾角、颏唇沟深度增加;但2组在各项测量项目的变化上无显著组间差别。结论:拔除第一前磨牙组垂直向生长更明显,拔除第二前磨牙组更倾向于颏部的水平向生长;2种拔牙模式在颏部软组织的改变上无显著差别。

PURPOSE： The purpose of this retrospective cephalometric study was to compare the change of chin soft tissue in patients with Class Ⅰ malocclusion after extraction of either first premolars or second premolars. METHODS： The pretreatment and posttreatment records of 50 patients were used in the study. Twenty-five patients underwent extraction of first premolars and 25 patients underwent extraction of second premolars. All the patients were skeletal Class Ⅰ and matched by the gender, age, facial divergence and crowding. The lateral cephalometric radiographs taken before and after treatment were traced and measured. The data was analyzed using SPSS 10,0 software package for Student＇s t test. RESULTS： （1）The horizontal and vertical changes was both significant in the second extraction group compared with first extraction group, and the horizontal change was more apparent. But only vertical change was apparent in the first extraction group. （2）In the soft tissue measurements, the value of soft tissue facial angle and B＇-Pos-FH in the first extraction group was less than those in the second extraction group significantly. After treatment all the patients had an increase in S-Ns-Pos angle, soft tissue facial angle, B＇-Pos-FH and depth of mentolabial groove. At the same time, soft tissue convexity angle was diminished obviously. But the change was not significant between the two premolar extraction groups. CONCLUSIONS： The growth pattern tends to vertical pattern in the first premolar extraction group and the horizontal growth of chin is more obvious in the second premolar extraction group. There is no significant difference of chin soft tissue changes between the two premolar extraction groups.