Postgraduate School of Orthodontics, University of Ferrara, Ferrara, Italy.
School of Economics, Management and Statistics, University of Bologna, Bologna, Italy.
Am J Orthod Dentofacial Orthop. 2020 Feb;157(2):218-227. doi: 10.1016/j.ajodo.2019.03.024.
The aim of this study was to investigate the vestibular anatomy of teeth in samples of adult Italian and Mozambican subjects in ideal occlusion and permanent dentition and identify any anatomic characteristics that may influence bonding in the straight-wire technique.
Linear measurements and coordinates of each curve representing the clinical crown height and width of each tooth were acquired from digital models of each subject categorized to 1 of 2 groups: Italian (18 males, 22 females; mean age, 29.6 ± 5.7 years) or Mozambican (14 males, 15 females; mean age, 23.4 ± 5.9 years). All subjects had normal dentition and no previous orthodontic treatment, fillings, or prostheses. Method error and systematic error were calculated according to the Dahlberg formula (S = ∑ d/2n) and dependent Student t test (P <0.05), respectively. Tooth symmetry was investigated through a paired-samples t test (P <0.05) and sex difference via an independent-samples t test (P <0.05). After neither asymmetry nor sexual dimorphism was found, all data were pooled, inverting the signs of the X coordinates and then mirroring data. Subsequently, a 2-samples t test (P <0.05) and a multivariate cluster analysis were performed on the mirrored data to compare the 2 groups and to identify any within-group diversity for number of clusters for each tooth. Means of all linear measurements and coordinates (crown height and width) calculated for each cluster were reported and compared using a standard 2-samples t test (P <0.05).
Two clusters were identified for the maxillary second premolars and molars in Italian subjects, whereas in the Mozambican subjects, there were 2 clusters for the maxillary first premolars and lateral incisors and 3 clusters for the maxillary canines and central incisors. The mandibular arch was remarkably homogeneous, with only 1 cluster per tooth in each group. In the mandibular arch, statistical differences were recorded between ethnic groups in crown height at the central incisors and second molars and in crown width in the sector from the second premolar to the second molar.
There were considerable differences both between and within racial groups in crown height, crown width, and numbers of clusters, which should be taken into account during bonding. Although single-bracket placement guides specific for ethnicity may be feasible for the mandibular arch, the significant diversity in number of clusters in the maxillary arch indicates that more accurate bracket placement guides that take into account such heterogeneity are required.
本研究旨在调查意大利和莫桑比克成年人正常咬合和恒牙列中牙齿的前庭解剖结构，并确定可能影响直丝弓技术粘结的任何解剖特征。
从每位受试者的数字模型中获得代表每个牙齿临床冠高度和宽度的线性测量值和曲线坐标，并将其分为两组之一：意大利组（18 名男性，22 名女性；平均年龄 29.6±5.7 岁）或莫桑比克组（14 名男性，15 名女性；平均年龄 23.4±5.9 岁）。所有受试者均具有正常的牙列，且未接受过正畸治疗、补牙或镶牙。根据 Dahlberg 公式（S=∑d/2n）计算方法误差和系统误差，分别采用配对样本 t 检验（P<0.05）。通过配对样本 t 检验（P<0.05）研究牙齿对称性，通过独立样本 t 检验（P<0.05）研究性别差异。在未发现不对称或性别二态性后，将所有数据汇总，反转 X 坐标的符号，然后镜像数据。随后，对镜像数据进行 2 样本 t 检验（P<0.05）和多元聚类分析，以比较两组，并为每组的每个牙齿确定聚类的数量。报告所有线性测量值和坐标（冠高和冠宽）的平均值，并使用标准的 2 样本 t 检验（P<0.05）进行比较。
意大利受试者的上颌第二前磨牙和磨牙有 2 个聚类，而莫桑比克受试者的上颌第一前磨牙和侧切牙有 2 个聚类，上颌尖牙和中切牙有 3 个聚类。下颌弓非常均匀，每组每颗牙齿只有 1 个聚类。在下颌弓中，在中切牙和第二磨牙的牙冠高度以及第二前磨牙到第二磨牙区域的牙冠宽度方面，两组之间存在统计学差异。
在牙冠高度、牙冠宽度和聚类数量方面，种族之间存在很大差异，这在粘结过程中需要考虑。尽管针对特定种族的单托槽定位器可能适用于下颌弓，但上颌弓中聚类数量的显著多样性表明，需要更准确的托槽定位器，以考虑到这种异质性。
