下颌第二磨牙阻生的预防及其早期矫治的初步研究

Prevention of impacted mandibular second molar and its early orthodontic study

目的:探寻下颌第二磨牙阻生的危险因素,为早期矫治提供理论依据。方法:选取119例12-16岁正畸患者,根据下颌第二磨牙萌出情况分为阻生组和萌出组。测量上下颌骨多个变量进行两独立样本t检验,应用logistic回归分析确定下颌第二磨牙阻生的危险因素。结果:阻生组的SNB、ANB、下颌平面角(MP-FH)大于萌出组(P<0. 05),而下颌体长度(Go-Po)小于萌出组(P<0. 05)。两组间SNA、Y轴角、下颌骨长度(Co-Po)、下颌升支长度(Co-Go)、前下面高(ANS-Me)、下颌升支长度与下颌骨长度的比值(Co-Go/Co-Po)的差异没有统计学意义(P> 0. 05)。SNB、ANB、MP-FH是下颌第二磨牙阻生的危险因素。随访达2年时,两组间的ANB、MP-FH、Go-Po和SNB均没有统计学意义(P> 0. 05)。结论:骨性Ⅱ类高角患者更易发生下颌第二磨牙阻生。

Objective: To explore the risk factors of impacted mandibular second molar and provide theoretical basis for early orthodontic treatment. Methods: 119 orthodontic patients aged 12-16 year old were selected to the impaction group and the eruption group. Two independent samples t test and logistic regression analysis were used to determine the risk factors of impacted mandibular second molars. Results: SNB、ANB and MP-FH in the impaction group were larger than those in the eruption group(P<0.05), while Go-Po was less than that in the eruption group(P<0.05). There was no significant difference in SNA, Y-axis, Co-Po, Co-Go, ANS-Me and Co-Go/Co-Po between the two groups(P>0.05). SNB, ANB and MP-FH are risk factors for impaction of mandibular second molars. There was no statistically significant difference in ANB,MP-FH, Go-Po and SNB between the two groups at the end of the 2 years’ follow-up(P>0.05). Conclusion: The mandibular second molar impaction is more likely to occur in the patients with skeletal pattern II with high angle.