Relationship of maxillary 3-dimensional posterior occlusal plane to mandibular spatial position and morphology

Introduction: The purpose of this study was to examine the relationship of the 3-dimensional (3D) posterior occlusal plane (POP) and the mandibular 3D spatial position. The relationship of the POP to mandibular morphology was also investigated. Methods: Retrospective data from a convenience sample of pretreatment diagnostic cone-beam computed tomography scans were rendered using InVivo software (Anatomage, San Jose, Calif). The sample consisted of 111 subjects (51 male, 60 female) and included growing and nongrowing subjects of different races and ethnicities. The 3D maxillary POP was defined by selecting the cusp tips of the second premolars and the second molars on the rendered images of the subjects. The angles made by this plane, in reference to the Frankfort horizontal plane, were measured against variables that described the mandibular position in the coronal, sagittal, and axial views. The POP was also compared with bilateral variables that described mandibular morphology. Results: There were significant differences of the POP among the different skeletal malocclusions (P < 0.0001). The POP showed significant correlations with mandibular position in the sagittal (P < 0.0001), coronal (P < 0.05), and axial (P < 0.05) planes. The POP also showed a significant correlation with mandibular morphology (P < 0.0001). Conclusions: These findings suggest that there is a distinct and significant relationship between the 3D POP and the mandibular spatial position and its morphology.