Correlation Between Gonial Angle and Mandibular Symphysis Width in South Indian Dravidian Population

Abstract

Mandibular growth pattern (MGP) prediction plays an important role in orthodontic treatment planning. This study sought to assess the mandibular symphyseal width in adolescents with different mandibular growth patterns (MGPs) so as to see whether a correlation exists. This study was conducted on 90 lateral cephalograms of patients aged between 10 and 16 years. The subjects were divided into normo-divergent, hypodivergent and hyperdivergent subgroups based on the gonial angle. The symphyseal measurement included width or depth of the mandibular symphysis according to Akietal study. He suggested that a mandible with anterior growth direction was associated with a large depth of the symphysis. In contrast, a mandible with a posterior growth direction was associated with a small depth of symphysis. To assess the correlation between mandibular symphyseal width and mandibular growth pattern, Pearson’s correlation test was done. Correlation is significant at the 0.01 level (2 tailed). A P-value which is less than 0.05 was considered statistically significant. The mandibular symphyseal width was found to be strongly associated with the MGP. It can be inferred from the results that in vertical growth pattern, as the gonial angle increases, symphyseal width decreases and in horizontal growth pattern, as the gonial angle decreases, symphyseal width increases. Also, in vertical growth pattern subjects, the mandibular symphyseal width is narrower. In contrast, in horizontal growth pattern subjects, the mandibular symphyseal width is wider.