骨性Ⅲ类与Ⅰ类错患者基骨及牙弓宽度的比较研究

目的：评价骨性Ⅲ类错合与骨性I类个别正常合上下颌第一磨牙区基骨及牙弓宽度差异。方法：选取骨性Ⅲ类错合患者与骨性I类个别正常合样本各30例。测量CBCT数据中上颌骨颧弓点和下颌第一磨牙阻抗中心对应的颊侧骨皮质点间的距离作为基骨宽度；测量模型上下颌第一磨牙中央窝之间的距离作为牙弓宽度。使用SPSS 22.0独立样本t检验。结果：上颌基骨宽度Ⅲ类组（63.96±3.78mm）小于I类组（65.67±2.76mm）；下颌基骨宽度Ⅲ类组（62.26±3.12mm）大于I类组（60.29±3.15mm）；基骨宽度差为Ⅲ类组（2.31±2.41mm）小于I类组（5.38±1.24mm）。差异均有统计学意义（P<0.05）。Ⅲ类组与I类组上下颌牙弓宽度均无组间差异（P>0.05）。结论：骨性Ⅲ类患者存在上下颌基骨横向发育不调及上下颌磨牙的颊舌向代偿。

A comparative study of basal and dental arch width in skeletal Class Ⅲ malocclusion and Class Ⅰ normal occlusion

Object To evaluate the maxillomandibular transverse basal discrepancies and dental arch discrepancies in the first molar area, and to compare values between skeletal Class III malocclusion and Class I normal occlusion groups. Methods CBCT scans of 30 patients with skeletal Class III malocclusion and 30 with Class I normal occlusion were evaluated. Basal bone width were measured as the distance between zygomatic arch point for the maxilla and for the mandible measured between the most buccal point on the cortical plate opposite the mandible first molars at the level of the center of resistance. Dental arch width were measured as the distance between the right and left fovea of the first molars using dental casts. Independent-sample t tests were used with SPSS(version 22). Results by comparing the skeletal Class III groups and the Class I normal occlusion groups ,the maxillary basal bone width, the mandibular basal bone width, the maxillomandibular basal bone discrepancies showed significant difference (P<0.05) with skeletal Class III groups (63.96±3.78mm) smaller than Class I normal occlusion groups （65.67±2.76mm）, skeletal Class III groups (62.26±3.12mm) bigger than Class I normal occlusion groups （60.29±3.15mm）, skeletal Class III groups (2.31±2.41mm) smaller than Class I normal occlusion groups（5.38±1.24mm）respectively. In the contrast, there was no significant difference in the dental arch width (P>0.05). Conclusion Skeletal Class III malocclusion groups tend to show maxillomandibular transverse basal bone disharmony and compensatory inclination.