Singh G D, McNamara J A, Lozanoff S
Dept. of Dental Surgery and Periodontology, Dundee Dental Hospital & School, University of Dundee, Scotland, UK.
Angle Orthod. 1998 Oct;68(5):409-18. doi: 10.1043/0003-3219(1998)068<0409:MMISWC>2.3.CO;2.
The absence of physical restraint may be associated with a mandibular allometry that contributes to mandibular prognathism. Cephalographs of 73 prepubertal children of European American descent with untreated Class III malocclusions were traced and eight mandibular landmarks digitized. The resulting eight-noded geometries were normalized, and the mean Class III geometry compared with the equivalent Class I average. Procrustes analysis established statistical difference (p < 0.05) between these mean configurations. A color-coded finite-element (FEM) analysis was used to localize differences in morphology. Comparing Class III and normal mandibular configuration for changes in size, FEM revealed positive allometry of the mandibular corpus and around supramentale (15% increase in size), with reductions (30%) between the incisor alveolus and menton. For changes in shape, mandibular configurations were predominantly isotropic, with the exception of the anisotropic anterior region in the Class III subjects. Incremental growth differences are consistent with the view that the absence of physical restraint is associated with mandibular prognathism.
缺乏身体限制可能与下颌异速生长有关，这种异速生长会导致下颌前突。对73名未经治疗的Ⅲ类错牙合的欧美裔青春期前儿童的头颅侧位片进行描图，并对八个下颌标志点进行数字化处理。将得到的八节点几何图形进行归一化处理，并将Ⅲ类平均几何图形与相应的Ⅰ类平均值进行比较。普氏分析确定了这些平均构型之间的统计学差异（p < 0.05）。采用彩色编码有限元（FEM）分析来定位形态学上的差异。比较Ⅲ类和正常下颌构型的大小变化，有限元分析显示下颌体和颏下点周围呈正异速生长（大小增加15%），而切牙牙槽和颏下点之间则减小（30%）。对于形状变化，下颌构型主要是各向同性的，Ⅲ类受试者的各向异性前部区域除外。生长增量差异与缺乏身体限制与下颌前突有关的观点一致。
