成人骨性Ⅲ类错牙合患者正畸去代偿前后下切牙区牙槽骨形态特征的CBCT研究

CBCT research of alveolar bone condition around mandibular incisors in adults with skeletal class Ⅲ malocclusion before and after orthodontic decompensation

目的比较正畸去代偿前后严重的成人骨性Ⅲ类错牙合患者下切牙区牙槽骨形态变化情况。方法对15例接受正畸-正颌联合治疗的严重成人骨性Ⅲ类错牙合患者(男9例,女6例,平均年龄23.6岁),分别在治疗前(T0期)和正颌手术前1个月(T1期)进行CBCT摄片。分别测量正畸前及术前正畸结束时下切牙区牙槽骨形态,包括牙槽骨厚度、牙槽骨附着高度、牙根长度等指标。相关数据采用SPSS15.0统计软件进行配对t检验。结果正畸去代偿前后的比较结果显示:1正畸去代偿以后下切牙唇倾度增大,根尖点距舌侧骨皮质距离变小(P<0.01);2牙槽骨厚度未见明显改变;3唇舌侧牙槽骨附着高度矫治后均有降低,尤其是舌侧牙槽骨附着高度降低显著(P<0.01);4牙根长度测量未见明显改变。当下切牙进行较大范围的唇向倾斜运动时,牙根向舌侧骨皮质靠近,牙槽骨附着高度进一步降低。结论在成人骨性Ⅲ类错牙合的矫治中,由于需要在不良的牙槽骨形态中移动下切牙,必须密切关注其牙周组织状况、牙槽骨形态变化以及牙根与牙槽骨的关系,选择恰当的矫治方案,减少下切牙过度地唇舌向移动,避免不良反应的发生。

Objective To compare alveolar bone conditions around mandibular incisors in the adult of skeletal classⅢ malocclusion before treatment and after the presurgical orthodontic treatment. Methods 15 patients treated with orthodontic treatment and orthog-nathic surgery （9 men, 6 women, average age：23.6 years） took CBCT before treatment （T0） and 1 month before orthognathic surgery （T1）.The amount of alveolar bone thickness, the vertical alveolar level and the root length were measured. Paired t-test was performed for the comparisons of the differences between pre-and post-operative variables using SPSS15.0. Results ①The lower incisors incli-nation was increased and the incisors root apex was closer to the lingual side of alveolar bone （ P〈0.01）;② The alveolar bone thick-ness at apex was not statistically changed;③The vertical alveolar bone levels at the labial and lingual sides were both significantly re-duced especially at the lingual side after presurgical orthodontic treatment （ P〈0.01）;④The root length was not significantly changed. When the lower incisor inclined to the lip in a wide range, the tooth root moved closer to the lingual bone cortex, and the attachment height of alveolar bone lowered more. Conclusion In the treatment of adults with skeletal class Ⅲ malocclusion, special attention should be given to the patients’ periodontal health, the change of alveolar bone and the relationship between root and alveolar bone. A right plan should be chosen to decrease the excessive movement of lower incisors so as to avoid adverse reaction.