The correlations between vertical maxillary asymmetry and orbital volume in Taiwanese adults

Facial asymmetry often results from discrepancies between the maxilla and mandible. As the maxilla contributes to the orbital floor and lateral wall, variations in its inclination may affect orbital morphology and volumetric symmetry. This study investigated the relationship between orbital volume (OV) and vertical maxillary asymmetry (VMA) and evaluated influencing factors such as sex, age, height, and skeletal pattern. Cone-beam computed tomography scans of 94 participants (47 men and 47 women) were analyzed. OV, right–left OV discrepancy (DOV), maxillary dimensions, and VMA (mm) were measured. VMA was defined as the vertical height difference between the right and left jugal points relative to the superior facial plane. Participants were divided into three groups on the basis of VMA: Group 1 (–1 < VMA < 1, normal symmetry), Group 2 (–1 ≤ VMA ≤ –2 or 1 ≤ VMA ≤ 2, mild asymmetry), and Group 3 (VMA >2 or <−2, significant asymmetry). Intergroup differences and correlations between OV and VMA were statistically assessed. Mean OV values were 24.25, 23.64, and 23.90 mm³ for Group 1 (n = 34), Group 2 (n = 31), and Group 3 (n = 29), showing no significant intergroup differences. OV was significantly correlated with sex and height, being larger in men and taller individuals. In Group 3, DOV were positively correlated with VMA. Although overall OV and maxillary dimensions did not differ among groups, greater VMA was significantly associated with increased DOV, suggesting that enhanced maxillary asymmetry corresponds to greater orbital volumetric differences.