Abstract

ABSTRACTObjective: The purpose of this study was to establish the association between sagittal and vertical skeletal patterns and assess which cephalometric variables contribute to the possibility of developing skeletal Class II or Class III malocclusion. Methods: Cross-sectional study. The sample included pre-treatment lateral cephalogram radiographs from 548 subjects (325 female, 223 male) aged 18 to 66 years. Sagittal skeletal pattern was established by three different classification parameters (ANB angle, Wits and App-Bpp) and vertical skeletal pattern by SN-Mandibular plane angle. Cephalometric variables were measured using Dolphin software (Imaging and Management Solutions, Chatsworth, Calif, USA) by a previously calibrated operator. The statistical analysis was carried out with Chi-square test, ANOVA/Kruskal-Wallis test, and an ordinal multinomial regression model. Results: Evidence of association (p< 0.05) between sagittal and vertical skeletal patterns was found with a greater proportion of hyperdivergent skeletal pattern in Class II malocclusion using three parameters to assess the vertical pattern, and there was more prevalent hypodivergence in Class III malocclusion, considering ANB and App-Bpp measurements. Subjects with hyperdivergent skeletal pattern (odds ratio [OR]=1.85-3.65), maxillary prognathism (OR=2.67-24.88) and mandibular retrognathism (OR=2.57-22.65) had a significantly (p< 0.05) greater chance of developing skeletal Class II malocclusion. Meanwhile, subjects with maxillary retrognathism (OR=2.76-100.59) and mandibular prognathism (OR=5.92-21.50) had a significantly (p< 0.05) greater chance of developing skeletal Class III malocclusion. Conclusions: A relationship was found between Class II and Class III malocclusion with the vertical skeletal pattern. There is a tendency toward skeletal compensation with both vertical and sagittal malocclusions.

Highlights

  • IntroductionAccording to Bjork and Skieller[1], the total rotation of the mandible during growth is the result of the combination of matrix rotation (with its center at the condyles) and the intramatrix rotation (with its center somewhere in the corpus)

  • According to Bjork and Skieller[1], the total rotation of the mandible during growth is the result of the combination of matrix rotation and the intramatrix rotation

  • The normal vertical skeletal pattern was the greatest proportion for both Class II and Class III malocclusion groups

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Summary

Introduction

According to Bjork and Skieller[1], the total rotation of the mandible during growth is the result of the combination of matrix rotation (with its center at the condyles) and the intramatrix rotation (with its center somewhere in the corpus). These rotation patterns suffer marked variations in individuals with hyperdivergent or hypodivergent vertical patterns. Chung and Wong[5] studied the changes in craniofacial growth in skeletal Class II subjects aged from 9 to 18 years, with low, medium and high SN-mandibular plane angle; finding that, at the age of 9, the high angle group showed greater convexity, larger Y-axis and gonial angles, and greater anterior facial height. The trend toward a compensatory mechanism from the skeletal[6,7,8,9,10] and dental[5,11,12,13] structures when deviations occur in growth patterns is used to try to preserve a proportional and equilibrated facial pattern

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