Papagiannis Alexandros, Halazonetis Demetrios J
Department of Orthodontics, School of Dentistry, National and Kapodistrian University of Athens, Athens, Greece
Department of Orthodontics, School of Dentistry, National and Kapodistrian University of Athens, Athens, Greece.
Eur J Orthod. 2016 Apr;38(2):202-11. doi: 10.1093/ejo/cjv019. Epub 2015 Apr 3.
This study aimed to quantify the patterns of shape variability and the extent and patterns of shape covariation between the upper and lower dental arch in an orthodontic population.
Dental casts of 133 white subjects (61 males, 72 females; ages 10.6-26.6) were scanned and digitized in three dimensions. Landmarks were placed on the incisal margins and on the cusps of canines, premolars, and molars. Geometric morphometric methods were applied (Procrustes superimposition and principal component analysis). Sexual dimorphism and allometry were evaluated with permutation tests and age-size and age-shape correlations were computed. Two-block partial least squares analysis was used to assess covariation of shape.
The first four principal components represented shape patterns that are often encountered and recognized in clinical practice, accounting for 6-31 per cent of total variance. No shape sexual dimorphism was found, nevertheless, there was statistically significant size difference between males and females. Allometry was statistically significant, but low (upper: R(2) = 0.0528, P < 0.000, lower: R (2) = 0.0587, P < 0.000). Age and shape were weakly correlated (upper: R(2) = 0.0370, P = 0.0001, lower: R (2) = 0.0587, P = 0.0046). Upper and lower arches covaried significantly (RV coefficient: 33 per cent). The main pattern of covariation between the dental arches was arch width (80 per cent of total covariance); the second component related the maxillary canine vertical position to the mandibular canine labiolingual position (11 per cent of total covariance).
Results may not be applicable to the general population. Age range was wide and age-related findings are limited by the cross-sectional design. Aetiology of malocclusion was also not considered.
Covariation patterns showed that the dental arches were integrated in width and depth. Integration in the vertical dimension was weak, mainly restricted to maxillary canine position.
本研究旨在量化正畸人群中上下牙弓形状变异的模式以及形状协变的程度和模式。
对133名白人受试者（61名男性，72名女性；年龄10.6 - 26.6岁）的牙模进行三维扫描和数字化处理。在切缘以及尖牙、前磨牙和磨牙的牙尖上设置地标点。应用几何形态测量方法（普氏叠加和主成分分析）。通过置换检验评估性别二态性和异速生长，并计算年龄 - 大小和年龄 - 形状相关性。使用双块偏最小二乘法分析来评估形状协变。
前四个主成分代表了临床实践中常见且可识别的形状模式，占总方差的6% - 31%。未发现形状上的性别二态性，但男性和女性之间存在统计学上显著的大小差异。异速生长具有统计学意义，但程度较低（上颌：R(2)=0.0528，P < 0.000，下颌：R(2)=0.0587，P < 0.000）。年龄与形状的相关性较弱（上颌：R(2)=0.0370，P = 0.0001，下颌：R(2)=0.0587，P = 0.0046）。上下牙弓存在显著的协变（RV系数：33%）。牙弓之间协变的主要模式是牙弓宽度（占总协方差的80%）；第二个成分将上颌尖牙的垂直位置与下颌尖牙的唇舌向位置相关联（占总协方差的11%）。
结果可能不适用于一般人群。年龄范围较宽，且与年龄相关的发现受横断面设计的限制。错牙合畸形的病因也未被考虑。
协变模式表明牙弓在宽度和深度上是整合的。在垂直维度上的整合较弱，主要限于上颌尖牙的位置。
