Huang Chun, Wen Xin, Huang Le, Ning Zhao
Department of Stomatology, Shanghai Ikang Junan Clinic. Shanghai 200052, China. E-mail:
Shanghai Kou Qiang Yi Xue. 2022 Oct;31(5):550-555.
To evaluate the effects of three-dimensional maxillary protraction simulation using cone-beam CT (CBCT) on the width of the upper and lower jaws in early permanent dentition patients with skeletal Class Ⅲ malocclusion.
Twenty skeletal Class Ⅲ malocclusion and 20 skeletal Class I patients according to the inclusion criteria from the Department of Orthodontics，Shanghai Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine between January 2016 and January 2021,were selected in this study. CBCT images were taken in all patients before treatment, and Mimics 20.0 software was used to measure the buccal-lingual inclination of the first molars and the width of the dental and basal arch of two groups of patients. Three-dimensional segmentation and maxillary forward movement simulation were performed to evaluate the dental and basal arch width after the sagittal relationship between the maxilla and mandible were changed. SPSS 21.0 software package was used for statistical analysis of the data.
The maxillary molars inclined buccally and the mandibular molars inclined lingually in Class Ⅲ patients(P<0.01); there was no significant difference in the width of the mandibular basal arch between Class Ⅲ and Class I , but the width of the maxillary base arch in Class Ⅲ was significantly smaller than that in Class I (P<0.01), the difference between the maxillary and mandibular base arch widths of Class Ⅲ was significantly smaller than that of class I(P<0.01); however, there was no significant differences in the width of the maxillary and mandibular dental arches between the two groups. During the maxillary protraction simulation in Class Ⅲ patients, the width of the maxillary dental arch of Class Ⅲ was significantly larger than that of the mandible when the maxilla was moved 3 mm forward(P<0.05). The width of maxillary basal arch and the difference between upper and lower basal arch width were still smaller than that of Class I when moving 2 mm(P<0.05); but when the forward movement was 3 mm, there were no significant difference in maxillary basal arch width and maxillomandibular basal coordination between Class Ⅲ and Class I (P>0.05).
Skeletal Class Ⅲ patients in early permanent dentition showed some insufficient development of maxillary basal arch width and buccal inclination of maxillary molars. During maxillary protraction treatment, the width of dental and basal arch change significantly with the amount of maxillary forward movement and mandibular rotation. The sagittal change of the upper and lower jaws is one of the most important factors to decide whether the maxillary expansion is needed. If the change exceeds 3mm, maxillary expansion might not be necessary.
评估使用锥形束CT（CBCT）进行三维上颌前牵引模拟对恒牙早期骨性Ⅲ类错牙合患者上下颌宽度的影响。
选取2016年1月至2021年1月上海交通大学医学院附属第九人民医院正畸科符合纳入标准的20例骨性Ⅲ类错牙合患者和20例骨性Ⅰ类患者。所有患者在治疗前拍摄CBCT图像，使用Mimics 20.0软件测量两组患者第一磨牙的颊舌向倾斜度以及牙弓和基骨弓宽度。进行三维分割和上颌前徙模拟，以评估上颌与下颌矢状关系改变后的牙弓和基骨弓宽度。使用SPSS 21.0软件包对数据进行统计分析。
Ⅲ类患者上颌磨牙颊倾，下颌磨牙舌倾（P<0.01）；Ⅲ类与Ⅰ类患者下颌基骨弓宽度无显著差异，但Ⅲ类患者上颌基骨弓宽度显著小于Ⅰ类患者（P<0.01），Ⅲ类患者上颌与下颌基骨弓宽度差值显著小于Ⅰ类患者（P<0.01）；然而，两组患者上颌和下颌牙弓宽度无显著差异。在Ⅲ类患者上颌前牵引模拟过程中，上颌前移3mm时，Ⅲ类患者上颌牙弓宽度显著大于下颌（P<0.05）。上颌前移2mm时，Ⅲ类患者上颌基骨弓宽度以及上下基骨弓宽度差值仍小于Ⅰ类患者（P<0.05）；但前移3mm时，Ⅲ类与Ⅰ类患者上颌基骨弓宽度以及上下颌基骨协调性无显著差异（P>0.05）。
恒牙早期骨性Ⅲ类患者表现出上颌基骨弓宽度发育不足以及上颌磨牙颊倾。在上颌前牵引治疗过程中，牙弓和基骨弓宽度随上颌前徙量和下颌旋转量而显著变化。上下颌的矢状变化是决定是否需要上颌扩弓的最重要因素之一。如果变化超过3mm，可能无需进行上颌扩弓。
