Yan Mengdie, He Longwen, Zhang Wenzhong, Xie Yueqiang
Department of Orthodontics, Stomatological Hospital, School of Stomatology, Southern Medical University, S366 Jiangnan Boulevard, Haizhu District, Guangzhou City, Guangdong Province, 510280, China.
BMC Oral Health. 2025 Jul 2;25(1):1023. doi: 10.1186/s12903-025-06354-y.
This study evaluated changes in the mesiodistal angulation of the maxillary lateral incisors during extraction with clear aligners using panoramic images reconstructed from cone-beam computed tomography (CBCT) images and identified the main influencing factors for reducing the distal inclination of the maxillary lateral incisors during extraction.
This study analyzed 27 patients (mean age 21.1 ± 4.9 years; 18 women, 9 men) who underwent extraction with clear aligners. In total, 54 maxillary lateral incisors were included-each patient contributed two teeth. CBCT scans were obtained at pretreatment and refinement. The projection of the midpalatal suture on the panoramic image helped measure the axial angulation of the maxillary lateral incisors. Three-dimensional reconstruction was performed using Mimics, and the maxillary structure superimpose method was employed to measure the horizontal distance of the maxillary lateral incisors. Influencing factors, including lateral incisor attachment, lateral incisor horizontal movement distance, upper dentition retraction method, and lateral incisor crown-to-root ratio, were analyzed. P < 0.05 was considered statistically significant.
Maxillary lateral incisors are prone to distal inclination during orthodontic extraction using a clear aligner (P < 0.001). Notably, the angulation of maxillary lateral incisors significantly decreased in both groups, with larger decreases in the nonattachment groups (P < 0.001). Significant differences were observed between different retraction methods (P < 0.05) and horizontal movement distances of the lateral incisors (P < 0.001), but none among the different crown-to-root ratios (P > 0.05).
During extraction by clear aligner, changes in the mesiodistal angulation of the maxillary lateral incisor should be considered to ensure satisfactory treatment outcomes. By adding attachments and designing the canine first retraction method, the distal inclination of the lateral incisors can be reduced.
本研究利用从锥形束计算机断层扫描（CBCT）图像重建的全景图像，评估使用透明矫治器拔牙过程中上颌侧切牙近远中倾斜度的变化，并确定拔牙过程中减少上颌侧切牙远中倾斜的主要影响因素。
本研究分析了27例接受透明矫治器拔牙的患者（平均年龄21.1±4.9岁；女性18例，男性9例）。总共纳入54颗上颌侧切牙，每位患者贡献两颗牙齿。在治疗前和精调阶段进行CBCT扫描。腭中缝在全景图像上的投影有助于测量上颌侧切牙的轴向倾斜度。使用Mimics进行三维重建，并采用上颌结构叠加法测量上颌侧切牙的水平距离。分析了包括侧切牙附件、侧切牙水平移动距离、上颌牙列后移方法和侧切牙冠根比等影响因素。P<0.05被认为具有统计学意义。
使用透明矫治器进行正畸拔牙时，上颌侧切牙容易出现远中倾斜（P<0.001）。值得注意的是，两组上颌侧切牙的倾斜度均显著降低，非附件组降低幅度更大（P<0.001）。不同后移方法（P<0.05）和侧切牙水平移动距离（P<0.001）之间存在显著差异，但不同冠根比之间无显著差异（P>0.05）。
在使用透明矫治器拔牙过程中，应考虑上颌侧切牙近远中倾斜度的变化，以确保获得满意的治疗效果。通过增加附件并设计尖牙优先后移方法，可以减少侧切牙的远中倾斜。
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