Class II malocclusion with maxillary protrusion from the deciduous through the mixed dentition: a longitudinal study.

摘要

The aim of this study was to analyze the skeletal characteristics of Class II malocclusion with maxillary protrusion in the deciduous dentition and to describe the growth features of this type of skeletal imbalance during the transition from the deciduous through the mixed dentition. A group of 17 subjects having skeletal Class II malocclusions in the deciduous dentition due to maxillary protrusion was compared with a control group of 30 untreated subjects with ideal occlusion at the same stage of development. Both groups were observed for the first time in the deciduous dentition (T(1)) and followed during the transition from the deciduous to the mixed dentition (T(2)). During this time no orthodontic treatment was provided. Lateral cephalograms were taken for all subjects at T(1) and T(2). A cephalometric analysis was performed based on a reference system that consisted of two perpendicular lines traced through stable basicranical structures. The results indicate that a Class II skeletal pattern due to a maxillary protrusion is established early in the deciduous dentition and remains unmodified in the transition to the mixed dentition. The maxilla appeared to be displaced forward in Class II subjects, whereas the mandibles of the Class I and Class II subjects did not show any significant differences at this stage of growth. In the passage from the deciduous through the mixed dentition, Class I and Class II subjects showed growth increments that were not significantly different from each other. Sucking habits appeared to be correlated with the skeletal maxillary protrusion.