Symphyseal Morphology in Sagittal Skeletal Discrepancies: A Retrospective Observational Study

TL;DR

This study found that jaw misalignment (skeletal class) is linked to changes in the shape of the lower jaw's midline, with specific patterns observed in different jaw types.

Contribution

The study identifies a weak negative correlation between ANB angle and symphysis height, and a moderate positive correlation between ANB and IMPA.

Findings

A weak negative correlation was found between ANB angle and symphysis height (r = −0.25, p < 0.01).

Class III subjects had significantly greater symphyseal height than Class II subjects (p < 0.001).

Class II subjects showed the highest IMPA values (p < 0.001).

Abstract

Background: The aim of this study was to evaluate the correlation between skeletal class and morphological patterns of the mandibular symphysis. Methods: The sample consisted of 90 patients with an average age of 18 years (44 > x > 12). In order to investigate any correlation between skeletal class and morphological patterns of the mandibular symphysis, the following tests were used: Pearson’s correlation test, Spearman’s test, and the analysis of variance test (ANOVA) followed by Tukey’s post hoc HDS test. The significance level was set at 0.050. Results: Pearson’s correlation test and ANOVA showed a weak negative correlation between malocclusion and symphyseal height. Therefore, as ANB increases, symphyseal height decreases (r = −0.25, p < 0.01). In addition, a strong positive correlation was found between ANB and IMPA (r = 0.47, p < 0.01). So, as ANB increases, IMPA increases. No statistically significant association was found between symphyseal morphology and IMPA (Spearman’s test). Conclusions: The analysis revealed a weak but statistically significant negative correlation between ANB angle and symphysis height, indicating that as sagittal discrepancy increases (higher ANB), the symphysis tends to be shorter (r = −0.25, p < 0.01). A moderate positive correlation was also found between ANB and IMPA (r = 0.47, p < 0.01), suggesting that a more pronounced Class II skeletal pattern is associated with greater incisor proclination. However, no significant relationship was observed between symphysis type (A/B/C) and IMPA. When comparing skeletal classes, Class III subjects displayed significantly greater symphyseal height than Class II subjects (p < 0.001), while Class II subjects showed the highest IMPA values (p < 0.001).

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