Maxillary dentoalveolar assessment following retraction of maxillary incisors: a preliminary study

ABSTRACT Objective: The aim of this preliminary study was to assess changes in tooth length and alveolar thickness following retraction of maxillary incisors. Methods: A total of 11 patients presenting severe maxillary dentoalveolar protrusion revealed by initial (T1) cone-beam computed tomography (CBCT), and whose treatment plan included extraction of maxillary first premolars and retraction of maxillary incisors, were selected and submitted to CBCT examination one month after the end of incisors retraction (T2). The premaxilla was assessed through seven axial slices by means of Dolphin ImagingTM software. In each of these slices, five measurements of the distance from the buccal cortical bone to the palatal cortical bone were performed. Tooth length of maxillary incisors (n = 44) was also measured in sagittal slices. Measurements were repeated after a two-week interval, and intraclass correlation coefficient (ICC) was used to test examiner calibration. Wilcoxon test was used to detect differences in measurements performed at the two time intervals. Results: The ICC was satisfactory for tooth length (0.890) and for premaxilla alveolar thickness measurements (0.980). Analysis of data showed no statistically significant differences (p > 0.05) in tooth length or alveolar thickness between the two-time intervals assessed. Conclusion: The force used in retraction of maxillary incisors in this research did not promote significant changes in tooth length of maxillary incisors or in premaxilla alveolar thickness.

摘要
目的：本初步研究旨在评估上颌前牙内收后，牙体长度与前上颌牙槽骨厚度的变化情况。
方法：共纳入11例经初始（T1）锥形束计算机断层扫描（cone-beam computed tomography，CBCT）确诊为重度上颌牙槽牙前突的患者，所有患者的治疗方案均包含拔除上颌第一前磨牙并内收上颌前牙。于上颌前牙内收结束1个月后，对所有患者进行第二次锥形束计算机断层扫描（T2）。采用Dolphin ImagingTM软件，通过7张轴向断层切片对前上颌骨进行评估：在每张切片中，分别5次测量颊侧骨皮质至腭侧骨皮质的距离；同时在矢状断层切片中测量44颗上颌前牙的牙体长度。测量操作于2周后重复进行，采用组内相关系数（intraclass correlation coefficient，ICC）检验检查者校准一致性；采用威尔科克森检验分析两次测量结果的差异。
结果：牙体长度测量的组内相关系数为0.890，前上颌骨牙槽厚度测量的组内相关系数为0.980，两项指标的一致性均较为理想。数据分析显示，两次测量的牙体长度与牙槽厚度均无统计学显著性差异（p>0.05）。
结论：本研究中用于上颌前牙内收的矫治力，未对上颌前牙的牙体长度或前上颌骨牙槽厚度产生显著影响。