Coronoid Process Asymmetry in Mandibular Deviation: A Clinical Morphological Analysis.

BACKGROUND

The relationship between asymmetric coronoid process morphology and mandibular deviation remains unclear.

PURPOSE: To measure the association between coronoid process asymmetry and skeletal mandibular deviation.

STUDY DESIGN, SETTING AND SAMPLE: Retrospective case-control study conducted at the Affiliated Stomatological Hospital of Kunming Medical University and the First People's Hospital of Yunnan Province. The study sample comprised a consecutive series of patients aged ≥18 years presenting for evaluation and management of craniofacial differences between March 2020 and December 2025. Exclusion criteria included systemic skeletal diseases (eg, congenital muscular torticollis), temporomandibular joint ankylosis, prior jaw surgery or maxillofacial trauma, hereditary maxillofacial deformities, and poor-quality radiographic images.

PREDICTOR VARIABLE: Mandibular deviation (cases: menton deviation ≥2 mm; controls: <2 mm).

MAIN OUTCOME VARIABLE(S): Coronoid process morphology measured as the absolute value of the difference in coronoid height and coronoid length.

COVARIATES: Age, sex (male/female), and angle between the A-point, Nasion, and B-point.

ANALYSES: Paired and independent t tests were used for intragroup and intergroup comparisons. Pearson correlation and multivariable regression assessed the relationship between coronoid height, deviation distance, and asymmetry. Statistical significance was set at P < .05.

RESULTS

The sample comprised 259 subjects with a mean age of 26.14 ± 6.90 years, of whom 90 (34.75%) were male. Of these, 158 (61.00%) subjects formed the deviation group and 101 (39.00%) formed the control group. The deviation group exhibited statistically significantly greater absolute bilateral differences in coronoid height (1.77 ± 1.45 mm vs 0.76 ± 0.58 mm; P < .001) and coronoid length (1.66 ± 1.40 mm vs 0.81 ± 0.72 mm; P < .001) compared with the control group. Pearson correlation analysis revealed a positive correlation between coronoid process height on the deviated side and deviation distance (r = 0.208, P = .009). Multivariable regression confirmed its independent association with asymmetry (b = 0.898, P < .001).

CONCLUSIONS AND RELEVANCE: Mandibular deviation correlates strongly with unilateral coronoid elongation, indicating that evaluating coronoid morphology improves the clinical assessment of mandibular asymmetry.