Three-dimensional analysis of maxillary asymmetry in patients with mandibular prognathism

Jaw deviation is a common feature of skeletal mandibular prognathism and often extends to the maxilla, complicating diagnosis and treatment planning in surgical orthodontic treatment. Since occlusion and maxillary morphology strongly influence mandibular position and facial balance, accurate evaluation of maxillary asymmetry is essential. Three-dimensional computed tomography (3D-CT) is more reliable than conventional two-dimensional cephalometric analysis, which is limited by distortion and structural overlap. This study aimed to quantify maxillary deviation in yawing and rolling directions and to classify morphological patterns using cluster analysis of 3D-CT data.

One hundred patients with skeletal mandibular prognathism were analyzed using 3D-CT. Eleven anatomical landmarks were digitized, and twelve asymmetry indices were calculated. Cluster analysis of yawing deviation produced three groups: mild deviation (70 patients), moderate deviation (23 patients), and severe deviation (7 patients). Rolling deviation also yielded three groups: mild deviation (39 patients), moderate deviation (52 patients), and severe deviation (9 patients). Combined analysis classified all cases into nine subgroups. Of those, 31% showed nearly symmetrical morphology, while 69% demonstrated varying degrees of maxillary asymmetry. Characteristic patterns included rolling deviation at the greater palatine foramen, yawing deviation in the posterior alveolar process, and mandibular fossa deviation with mild rolling features. Less frequent subgroups reflected complex and severe morphologies.

Approximately two-thirds of patients with mandibular prognathism exhibited maxillary asymmetry, predominantly in posterior alveolar and basal regions. Classification into nine subgroups clarified distinct deviation patterns, with four groups demonstrating clinically relevant characteristics. These results emphasize the critical role of maxillary morphology in jaw deviation and highlight the value of standardized 3D evaluation. Incorporating maxillary asymmetry patterns into treatment planning may enhance diagnostic accuracy, improve surgical orthodontic outcomes, and contribute to more predictable facial symmetry.