Ahlbrecht Carly A, Ruellas Antonio Carlos de Oliveira, Paniagua Beatriz, Schilling Juan A, McNamara James A, Cevidanes Lucia Helena Soares
Department of Orthodontics and Pediatric Dentistry, School of Dentistry, University of Michigan, Ann Arbor, Michigan, United States of America.
Department of Orthodontics and Pediatric Dentistry, Federal University of Rio de Janeiro, Rio de Janeiro, Rio de Janeiro, Brazil.
PLoS One. 2017 Jun 8;12(6):e0178728. doi: 10.1371/journal.pone.0178728. eCollection 2017.
The aim of this study was to test the reproducibility of three-dimensional (3D) surface models of maxillary incisors and to propose a characterization of root morphology. The sample was comprised of pre-treatment cone-beam computed tomography (CBCT) images of fifty-five patients. The CBCTs were used to construct 3D surface models of the maxillary incisors. The reproducibility of surface models was tested by repeated construction of them by two observers. A 3D surface model that corresponded to the average of all lateral and all central incisors was generated. 3D surface distances and vector differences were calculated for each individual tooth and the average of the teeth considered. The corresponding points on the 3D surface mesh for each subgroup were compared statistically to those of the neutral subgroup using shape analysis MANCOVA and Hotelling's t-statistic (p < 0.05). Repeated construction of surface models demonstrated adequate inter-rater reproducibility. The distribution of 3D models into root morphology subgroups was: blunt (11% and 26% of the central and lateral incisors, respectively), conical (15% of the central incisors), long (27% and 20% of the central and lateral incisors, respectively), and short (15% and 4% of the central and lateral incisors, respectively). Compared to the neutral average, statistically significant differences in root morphology were found for blunt, long, conical, and short central incisors and for blunt, long, and short lateral incisors. We can conclude that 3D surface models construction for upper incisors is reproducible. 3D shape analysis using CBCT images allows a phenotypic characterization of incisor root morphology.
本研究的目的是测试上颌切牙三维（3D）表面模型的可重复性，并提出牙根形态的特征描述。样本包括55例患者的治疗前锥形束计算机断层扫描（CBCT）图像。这些CBCT图像被用于构建上颌切牙的3D表面模型。由两名观察者重复构建表面模型来测试其可重复性。生成了一个与所有侧切牙和中切牙平均值相对应的3D表面模型。计算了每颗牙齿以及所考虑牙齿平均值的3D表面距离和向量差异。使用形状分析多变量协方差分析（MANCOVA）和霍特林T统计量（p < 0.05），将每个亚组在3D表面网格上的对应点与中性亚组的对应点进行统计学比较。表面模型的重复构建显示出足够的评分者间可重复性。3D模型在牙根形态亚组中的分布情况为：钝形（中切牙和侧切牙分别占11%和26%）、锥形（中切牙占15%）、长形（中切牙和侧切牙分别占27%和20%）和短形（中切牙和侧切牙分别占15%和4%）。与中性平均值相比，钝形、长形、锥形和短形中切牙以及钝形、长形和短形侧切牙在牙根形态上存在统计学显著差异。我们可以得出结论，上颌切牙的3D表面模型构建具有可重复性。使用CBCT图像进行的3D形状分析能够对上颌切牙的牙根形态进行表型特征描述。
