Gao J, Lv H M, Ma H M, Zhao Y J, Li X T
Department of Orthodontics, Peking University School and Hospital of Stomatology & National Center of Stomatology & National Clinical Research Center for Oral Diseases & National Engineering Research Center of Oral Biomaterials and Digital Medical Devices & Beijing Key Laboratory of Digital Stomatology & NHC Research Center of Engineering and Technology for Computerized Dentistry, Beijing 100081, China.
Department of Orthodontics, Guiyang Stomatological Hospital, Guiyang 550002, China.
Beijing Da Xue Xue Bao Yi Xue Ban. 2022 Aug 18;54(4):719-726. doi: 10.19723/j.issn.1671-167X.2022.04.022.
To explore the method of measuring root volume with cone-beam computed tomography (CBCT) three-dimensional reconstruction technology, and to study root length and root volume of upper and lower central incisors in patients with skeletal Class Ⅲ malocclusion treated by surgical orthodontic treatment.
Twenty patients with skeletal Class Ⅲ malocclusion undergoing surgical orthodontic treatment were selected. CBCT data at three time points, before decompensation treatment (T0), after decompensation treatment (before orthognathic surgery, T1), and the end of post-operative orthodontic treatment (T2) were collected. Three-dimensional reconstruction technology was used to measure the root length and root volume of the upper and lower central incisors (including total root volume, cervical root and apical root), calculate the percentage of reduction volume, and measure the distance of tooth movement after orthodontic treatment. Data were statistically analyzed by SPSS 20.0 software. Least significant difference (LSD) method was used for pair comparison between the groups subject to normal distribution, and non-parametric test was used for comparison between the groups not subject to normal distribution. The differences of root length and root volume of upper and lower incisors were compared, and the characteristics of root absorption were analyzed.
Root length and root volume of the upper and lower central incisors were reduced during the surgical orthodontic treatment ( < 0.05) in cases. Both the root volume of cervical root and apical root were significantly reduced ( < 0.05), the reduction of apical root was more significant. The percentage of root volume reduction of the upper central incisor was (30.51±23.23)%, and lower central incisor (23.24±11.96)%. Compared with the upper central incisor, the root volume reduction amount and percentage of the lower central incisor were smaller, and apical root volume reduction of the upper central incisor was greater than that of the lower central incisor, which was statistically significant ( < 0.05). During pre-surgical orthodontic treatment, maxillary central incisor palatal moving was in a controlled tipping manner, and the mandibular central incisor tipped labially.
In patients with skeletal Class Ⅲ malocclusion, root length and total root volume of upper and lower central incisors decreased during surgical orthodontic treatment. Root volume measurement indicated that the cervical root also had root resorption. The difference in root resorption of the upper and lower central incisors might be related to the distance and direction of teeth movement. CBCT three-dimensional reconstruction will compensate for the limitation of root length measurement in evaluating root resorption.
探讨利用锥束计算机断层扫描（CBCT）三维重建技术测量牙根体积的方法，并研究外科正畸治疗的Ⅲ类骨性错牙合患者上下颌中切牙的牙根长度和牙根体积。
选取20例接受外科正畸治疗的Ⅲ类骨性错牙合患者。收集去代偿治疗前（T0）、去代偿治疗后（正颌手术前，T1）及术后正畸治疗结束时（T2）三个时间点的CBCT数据。采用三维重建技术测量上下颌中切牙的牙根长度和牙根体积（包括总牙根体积、颈段牙根和根尖段牙根），计算体积减少百分比，并测量正畸治疗后牙齿移动距离。数据采用SPSS 20.0软件进行统计学分析。对正态分布的组间采用最小显著差（LSD）法进行两两比较，对非正态分布的组间采用非参数检验。比较上下颌切牙牙根长度和牙根体积的差异，并分析牙根吸收特点。
外科正畸治疗过程中，上下颌中切牙的牙根长度和牙根体积均减小（P<0.05）。颈段牙根和根尖段牙根体积均显著减小（P<0.05），根尖段牙根减小更显著。上颌中切牙牙根体积减少百分比为（30.51±23.23）%，下颌中切牙为（23.24±11.96）%。与上颌中切牙相比，下颌中切牙的牙根体积减少量和减少百分比均较小，且上颌中切牙根尖段牙根体积减少大于下颌中切牙，差异有统计学意义（P<0.05）。术前正畸治疗期间，上颌中切牙腭向移动呈控制性倾斜移动，下颌中切牙唇向倾斜移动。
Ⅲ类骨性错牙合患者在外科正畸治疗过程中，上下颌中切牙的牙根长度和总牙根体积减小。牙根体积测量表明颈段牙根也存在牙根吸收。上下颌中切牙牙根吸收的差异可能与牙齿移动的距离和方向有关。CBCT三维重建将弥补牙根长度测量在评估牙根吸收方面的局限性。
