高角骨性Ⅲ类错牙合牙齿倾斜位置特征

目的　了解高角Ⅲ类错牙合 畸形患者全牙轴倾及转矩特征，以期为临床治疗提供指导。 方法　收集符合纳入标准的高角骨性I类（13名）及Ⅲ类（11名）错牙合 畸形共计24名患者头颅CBCT影像Dicom数据，利用invivo 5.1软件进行全牙轴倾度及转矩测量。 结果　（1）高角I类及Ⅲ类左右同名牙倾斜度一致性较好，P＞0.05，此后左右同名牙数据一并处理。（2）高角Ⅲ类与I类矢状向比较：①高角Ⅲ类，上前牙根舌向转矩增大趋势，但仅在上尖牙表现统计学差异，P＜0.05；②高角Ⅲ类，下前牙根舌向转矩减小，P<0.05，差异有统计学意义；③ 高角Ⅲ类，上后牙近中轴倾、下后牙远中轴倾趋势，但差异无统计学意义，P>0.05。（3）高角Ⅲ类与I类横向比较：①高角Ⅲ类，上前牙远中轴倾增加，差异有统计学意义；下前牙轴倾变化趋势不明，仅下中切牙表现远中轴倾（P<0.05）；② 高角Ⅲ类，上后牙根舌向转矩增大，有统计学差异；下后牙根舌向转矩减小趋势，但差异无统计学意义。（4） 高角I类及Ⅲ类与Andrews正常牙合 矢状向及冠状向各牙倾斜位置比较：① 矢状向：高角I类Ⅲ类上下前牙根舌向转矩增大，上下后牙明显近中倾斜；② 冠状向：高角I类Ⅲ类上下前牙远中倾斜增大，上下后牙根舌向转矩加大。 结论　（1）高角骨性Ⅲ类牙齿位置在垂直方向的代偿表现强于矢状方向；（2）高角骨性Ⅲ类上下前牙唇舌向倾斜移动风险较高，移动时更应注重牙齿的整体移动；（3）高角骨性Ⅲ类上颌后牙明显颊向倾斜，上牙列横向扩展范围减小，扩弓后稳定性可能降低。

Characteristics of the inclined position of high-angle skeletal class III malocclusion

Objective　To investigate tip and torque characteristics of all teeth in patients with high-angle skeletal class III malocclusion in order to provide guidance for clinical treatment. Methods　Dicom data of cone-beam CT (CBCT) of 24 patients with high-angle skeletal class I (13 patients) and III malocclusion (11 patients) meeting the inclusion criteria were collected. Tip and torque of all teeth (except the third molar) were measured respectively by the software Invivo5.1.　Results　(1) Inclination angle of the same name teeth had a good consistency in high-angle skeletal class I class III, P＞0.05； the data of the same name teeth were processed together hereinafter. (2) Comparison of sagittal direction between class III and I. In class Ⅲ malocclusion: ① It was showing a trend of increase in the lingual root torque of the anterior upper teeth, but only the canines had significant differences, P＜0.05; ② Lingual root torque of anterior lower teeth had decreased with significant difference, P＜0.05.③ There was no significant difference in the trend of mesio-inclination of the upper posterior teeth and distal inclination of the lower posterior teeth, P＞0.05. (3)Horizontal comparison of direction of skeletal class I and Ⅲ: ①The distal inclination of the anterior teeth in the upper jaw increased with significant difference and only distal inclination of incisors of the lower jaw increased in significant differnce, P<0.05. ② Lingual root torque significantly increased in the upper posterior teeth but decreased in the lower posterior teeth without statistical differnce. (4) Comparison of high-angle skeletal I and III with normal sagittal and coronal inclination of Andrews: ① Sagittal direction: lingual root torque of the upper and lower anterior teeth of high-angle skeletal I and III increased and the upper and lower posterior teeth had significant mesio-inclination. ② Coronal direction: the distal inclination of the upper and lower anterior teeth of skeletal I and III with high angle increased, while the lingual torque of the upper and lower posterior teeth increased.　Conclusions　(1)The vertical compensation of high-angle skeletal class Ⅲ is more significant than that of sagittal compensation. (2) High-angle skeletal class Ⅲ of upper and lower anterior teeth have much higher risk of bucco (labial)-lingual tilting movement, and more attention should be paid to the overall movement of teeth when moving. (3) The posterior teeth of maxilla have obvious buccal inclination in high-angle skeletal class III and the lateral extension range of the upper dentition decreases, which may reduce the stability after arch expansion.