An estimation of craniofacial growth in the untreated Class III female with anterior crossbite

Abstract

The literature has little to say regarding the normal growth and development of untreated individuals with Class III malocclusion or anterior crossbite. In part, this paucity of information is because of the relatively low prevalence of these characteristics in European-American populations and the need, recognized by the lay public and health professionals, for treatment of these conditions. Given the absence of true longitudinal data, this study attempts to estimate the growth of the untreated individual with Class III malocclusion and anterior crossbite by evaluating large samples of untreated subjects at distinct developmental stages. Initially the morphologic characteristics of 2074 Japanese female patients who had anterior crossbite were evaluated cephalometrically before treatment. On the basis of the cephalometric analysis, all subjects who did not have a Class III molar relationship were excluded from further analysis, leaving a sample of 1376. The subjects then were classified into seven groups (120-256 subjects per group) according to Hellman's stages of dental development. Descriptive statistics for 28 measurements were calculated. The results of this study imply that the maxilla in Japanese females maintains a retruded relationship to the cranial base and does not become less retrusive with time. In contrast, the mandible is protrusive even in the late deciduous dentition and becomes more protrusive with time, making the discrepancy between the upper and lower jaws progressively more severe. Dental compensations in both arches become increasingly evident as development progresses, and the underlying skeletal and dentoalveolar imbalances also are reflected in the soft tissue profile.