Relationships between jaw deformity and the occlusal plane in cone beam computed tomography scans.

STATEMENT OF PROBLEM: Consistent findings about the relationships between jaw deformity and the occlusal plane are lacking. PURPOSE: The purpose of this clinical study was to explore the relationships between the occlusal plane and jaw deformity by measuring data obtained from cone beam computed tomography (CBCT) scans. MATERIAL AND METHODS: Reconstructed images simulated by using the Materialise Interactive Medical Image Control System (Mimics) software program of CBCT data of 80 participants with facial asymmetry and 42 participants from the normal control group were measured with a new 3-dimensional geometric morphologic measurement system. Fifteen craniofacial surfaces were marked at a point, line, or plane, measuring correlation distances and angles to analyze the relationship between jaw deformity and the inclination of the occlusal plane and other relevant facial features. The Student t test was used to analyze whether the difference in the occlusal plane between the jaw deformity group and the normal group was statistically significant (alpha=.05). The Pearson correlation was used to analyze the correlation among the jaw deformity, the occlusal plane, and other landmarks, and linear regression was used to analyze the relationships among them. RESULTS: A significant difference was found between the occlusal plane of the jaw deformity and that of the normal group (P<.001) and a significant positive correlation between the degree of mandibular deformity and the inclination of occlusal plane (P<.001). A linear relationship was found between the linear regression equation of the angle of the left occlusal plane and the midsagittal sagittal plane Y and the distance between the mental apex of chin and the midsagittal plane X (the mandibular deflection to the right was defined as positive) as Y=90.646+0.388X. Statistically significant differences were found in the deviation of the chin vertex from the midsagittal plane and the distance between the midlines of the maxillary and mandibular central incisors by more than 2 mm (P<.001). CONCLUSIONS: A positive correlation was found between the inclination of the occlusal plane and the degree of jaw deformity, with a linear relationship between them. These findings provide a theoretical basis for the clinical reconstruction of occlusal relationships with jaw deformity.