Correlation of alveolar bone thickness and central incisor inclination in skeletal Class I and II malocclusions with different vertical skeletal patterns: A CBCT study

Abstract

Introduction: This study aimed to assess the alveolar bone thickness (ABT) and labiolingual inclination of maxillary and mandibular central incisors in patients with Class I and II skeletal patterns with normal-angle, high-angle, and low-angle vertical patterns.

Methods: The study sample consisted of 200 cone-beam computed tomography scans of patients with skeletal Class I and II malocclusions. Each group was further divided into low-angle, normal-angle, and high-angle subgroups. Labiolingual inclinations of maxillary and mandibular central incisors and ABT were measured at 4 levels from the cementoenamel junction in the labial and lingual surfaces. The Kolmogorov-Smirnov test, independent t test, 2-way analysis of variance, and Spearman's correlation test were applied for statistical analyses.

Results: The only significant difference between Class I and II groups regarding the ABT was found at the labial side of the maxillary central incisor, 9 mm apical to the crest. At this level, the mean ABT was 0.87 mm in patients with a skeletal Class I malocclusion, which was significantly greater than that in patients with a skeletal Class II malocclusion with a mean ABT of 0.66 mm (P = 0.02). Comparisons among the vertical subgroups revealed that on the labial and lingual sides of the mandible, as well as the palatal side of the maxilla, significantly thinner alveolar bone was found in patients with high-angle growth patterns than those with normal-angle and low-angle patterns in both sagittal groups (P <0.05). Significant weak to moderate correlations were found between ABT and tooth inclination (P <0.05).

Conclusions: Significant differences in ABT covering central incisors between patients with skeletal Class I and II malocclusion are merely observed at the labial surface of the maxilla, 9 mm apical to the cementoenamel junction. Compared with patients with normal-angle and low-angle, those with a high-angle growth pattern and Class I and II sagittal relationships have thinner alveolar bone support around maxillary and mandibular incisors.