Department of Orthodontics, Egas Moniz High Institute for Health Science, Lisbon, Portugal.
Am J Orthod Dentofacial Orthop. 2013 Mar;143(3):310-6. doi: 10.1016/j.ajodo.2012.09.021.
The aims of this study were to investigate whether there is a different transverse morphologic pattern of dental arches among patients with different manifestations of Class II Division 2 incisor retroclination and to evaluate to what extent the pattern of smaller-than-average teeth in Class II Division 2 malocclusion is common to all groups studied. This information might clarify whether different Class II Division 2 phenotypes represent a single etiology or multiple etiologies.
The sample comprised 108 subjects with Class II Division 2 malocclusions, divided into 2 groups according to the type of incisor retroclination: group I included 43 Class II Division 2 subjects with retroclination exclusively of the maxillary central incisors, and group II included 65 Class II Division 2 subjects with retroclination of the 4 maxillary incisors. Maxillary and mandibular intercanine and intermolar widths as well as mesiodistal crown dimensions of the 4 maxillary and mandibular incisors were determined from the patients' initial study models. Mean values of all variables were compared between the 2 groups by sex with analysis of variance.
From the comparison between these 2 groups, no statistically significant differences were found for all transverse measurements (P >0.05). For all mesiodistal measurements analyzed, statistically significant differences between the groups were only found for the mean value of both maxillary lateral incisors' mesiodistal dimensions in both sexes (P <0.05).
It is not possible to attribute a characteristic pattern of dental arch-width and incisor mesiodistal dimensions to the different manifestations of incisor retroclination in Class II Division 2 malocclusion.
本研究旨在探讨不同表现型的上颌切牙Ⅱ类 2 分类错（牙合）反（牙合）患者的牙弓横向形态是否存在差异，以及Ⅱ类 2 分类错（牙合）中牙小畸形的模式在多大程度上普遍存在于所有研究组。这些信息可能有助于阐明不同的Ⅱ类 2 分类表型是否代表单一病因或多种病因。
样本包括 108 例Ⅱ类 2 分类错（牙合）患者，根据切牙反（牙合）的类型分为 2 组：组 I 包括 43 例上颌切牙仅反（牙合）的Ⅱ类 2 分类错（牙合）患者，组Ⅱ包括 65 例上颌 4 个切牙反（牙合）的Ⅱ类 2 分类错（牙合）患者。从患者的初始研究模型中确定上颌和下颌尖牙间及磨牙间宽度以及上颌和下颌 4 个切牙的近远中冠尺寸。对所有变量的平均值进行性别分析方差比较。
从这两组的比较中，所有横向测量值均无统计学差异（P>0.05）。在分析的所有近远中测量值中，仅在两性中上颌侧切牙近远中尺寸的平均值存在统计学差异（P<0.05）。
不能将牙弓宽度和切牙近远中尺寸的特征模式归因于Ⅱ类 2 分类错（牙合）中切牙反（牙合）的不同表现型。
