Orthopantomographic Study of Mandibular Morphology Across Different Growth Patterns: A Retrospective Data Analysis

Variations in mandibular morphology may significantly influence orthodontic treatment planning, particularly in different growth patterns. This study aimed to evaluate mandibular morphology using orthopantomogram (OPG) analyses to quantify the differences in ramus height, mandibular body length, gonial angle, and condylar morphology across different growth patterns, thereby providing insights for personalized orthodontic interventions.

A retrospective cohort study was conducted using the records of 120 subjects with skeletal Class I malocclusion, aged 18-35 years. The participants were divided into three groups (n=40 each) based on the Frankfort-mandibular plane angle (FMA): hypodivergent (<20°), normodivergent (20-30°), and hyperdivergent (>30°). The inclusion criteria were good-quality OPGs and cephalograms, subjects with no history of trauma, temporomandibular joint dysfunction, or previous orthodontic treatment. OPGs were manually traced to measure condylar height, ramus height, corpus height, mandibular body length, gonial angle, and condylar morphology (classified as oval, diamond, bird beak, or crooked finger). The intra- and inter-observer reliabilities were confirmed using intraclass correlation coefficients. The data were statistically analyzed.

Significant differences in mandibular morphology were observed across different growth patterns (p<0.05). The hyperdivergent subjects showed reduced condylar and ramus heights, increased gonial angles, and higher corpus heights, whereas the hypodivergent subjects exhibited increased posterior dimensions and reduced gonial angles. Normodivergent subjects had the longest mandibular body length. The condylar morphology varied, with predominant and atypical oval shapes (bird beak and crooked finger) more prevalent in hyperdivergent cases. Post hoc analyses confirmed distinct intergroup differences.

Mandibular morphology varied significantly in different growth patterns and influenced the ramus height, gonial angle, and condylar shape. These findings underscore the importance of tailored orthodontic strategies based on growth pattern-specific mandibular characteristics to enhance treatment precision and efficacy.