骨性Ⅰ、Ⅱ类不同垂直骨面型患者下颌前牙区皮质骨厚度与下切牙牙根位置的CBCT研究

目的:比较骨性Ⅰ、Ⅱ类不同垂直向个体下颌前牙区皮质骨厚度和下切牙牙根位置的差异。方法:本研究为回顾性观察性研究。共收集324例个体，其中男性141例，女性183例。测量个体下颌前牙区皮质骨厚度和下切牙牙根位置，使用单因素方差分析比较不同骨型个体下颌前牙区皮质骨厚度与下切牙牙根位置，使用线性相关分析研究骨性Ⅱ类患者随着下颌平面角增加皮质骨厚度变化趋势。结果:高角患者下颌前牙区皮质骨较均角和低角患者更薄，男、女性Ⅰ类高角根中唇舌侧厚度分别为0.50 mm、1.27 mm和0.35 mm、1.16 mm，低角为0.58 mm、1.82 mm和0.62 mm、1.77 mm( P<0.05， P<0.01)，Ⅱ类高角根中唇舌侧厚度分别为0.38 mm、1.14 mm和0.51 mm、1.35 mm，低角为0.83 mm、2.28 mm和0.97 mm、1.93 mm( P<0.001)。且高角患者牙根距离唇舌侧皮质骨距离更近( P<0.05， P<0.01， P<0.001)。在骨性Ⅱ类患者中，随着下颌平面角增加，骨皮质厚度变薄( P<0.001)。 结论:高角患者下颌前牙区皮质骨较薄，骨性Ⅱ类患者尤其明显，因此临床上应防止骨开裂和骨开窗的发生。

A CBCT study of the correlation of mandibular anterior cortical bone thickness and the position of mandibular incisors in skeletal Class Ⅰ and Class Ⅱ patients with different vertical patterns

Objective:To investigate the difference of mandibular anterior cortical bone thickness and the position of mandibular incisors among different vertical patterns in skeletal Class Ⅰ and Class Ⅱ patients.Methods:This study is a retrospective observational study. 324 CBCT images are collected, including 141 males and 183 females. Mandibular anterior cortical bone thickness and the position of mandibular incisors are measured. Difference of mandibular anterior cortical bone thickness and the position of mandibular incisors among skeletal patterns are analyzed using one-way analysis of variance. Correlation of mandibular plane angle and cortical bone thickness is analyzed using bivariate correlation.Results:The cortical bone thickness of mandibular anterior teeth is thinner in hyperdivergent patients than that in normo- and hypodivergent patients. The thickness of labial and lingual cortex in Class Ⅰ hyperdivergent patients are 0.50 mm and 1.27 mm in male, 0.35 mm and 1.16 mm in female, and that in Class Ⅰ hypodivergent patients are 0.58 mm and 1.82 mm in male, 0.62 mm and 1.77 mm in female ( P<0.05, P<0.01). The thickness of labial and lingual cortex in Class Ⅱ hyperdivergent patients are 0.38 mm and 1.14 mm in male, 0.51 mm and 1.35 mm in female, and that in Class Ⅰ hypodivergent patients are 0.83 mm and 2.28 mm in male, 0.97 mm and 1.93 mm in female ( P<0.001). The distance between root and buccal or lingual inner cortex is shorter in hyperdivergent patients ( P<0.05, P<0.01, P<0.001). In Class Ⅱ patients, the cortical bone thickness decreases when the mandibular plane angle increases ( P<0.001). Conclusions:The cortical bone thickness is thinner in hyperdivergent group. Orthodontists should pay more attention to hyperdivergent patients when proclining mandibular incisors due to thinner anterior cortical bone thickness so as to prevent dehiscence and fenestration.