A cone beam computed tomography study based on three-dimensional cephalometric analysis of relationships between the lip-line and jaw deformity.

OBJECTIVE: The aim of this study was to use the cone beam computed tomography (CBCT) to study the relationships between the lip-line and mandible deformity. DESIGN: CBCT data of 20 patients with jaw deformity (experimental group) and 20 patients without mandible deformity (control group) were selected. Use three-dimensional cephalometry to measure the reconstructed images of CBCT data simulated by the Materialise Interactive Medical Image Control System (Mimics), mark the related points, lines and planes of the three-dimensional craniomaxillofacial structure, and measure relevant distances and angles. The T-test, Pearson correlation analysis and Linear regression were used to analyze the characteristics of the lip-line and jaw deformity. RESULTS: There was a significant difference in the lip-line between mandible deformity group and control group. Significant positive correlations could been found among the lip-line cant, the occlusal plane cant, the mandibular plane cant and the degree of mandible deformity (r=0.964, 0.942, 0.611, P < 0.01). A linear relationship was found between the left lip-line cant Y and the menton deviation X [the mandible deflection to the right was defined as positive, and the left lip-line below frankfort horizontal was viewed as positive] as Y= 0.340 + 0.505X. CONCLUSIONS: The lip-line of patients with jaw deformity was inclined, and the lip-line cant was positively correlated with the degree of mandible deformity, and there was a certain linear relationship between the two, which could provide a theoretical reference for clinicians to diagnose and treat patients with mandible deformity.

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 (α=.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.

Cone-beam Computed Tomography-based three-dimensional cephalometric analysis of mandible symmetry and the occlusal plane of adult patients with high-angle skeletal class III malocclusion and jaw deformity.

OBJECTIVE: To use cone beam computed tomography (CBCT) scans to analyze mandibular symmetry, the occlusal plane and their correlations in patients with high-angle skeletal class III malocclusion and jaw deformity. DESIGN: Reconstructed images simulated of CBCT data of 20 adult patients with high-angle skeletal class III malocclusion and jaw asymmetry (Experimental group) and 20 adult patients of skeletal class I with normal faces (Control group) were measured with a three-dimensional (3D) geometric morphological measurement system. Related landmarks, lines and planes were marked and relevant distances and angles of 3D craniofacial structures were measured. The Student t-test was performed to assess symmetry. With the help of the Pearson correlation and Linear regression, we explored the correlations and other relationships among them. RESULTS: Compared with control group, the symmetrical differences in experimental group were concentrated in condyle, coracoid process, mandibular angle, mandibular first molar area and the chin (P < 0.05). A strong positive correlation was found between the degree of mandibular deviation and the inclination of the occlusal plane in the coronal position (r = 0.860, P < 0.001) and a linear relationship between them was found: Y = 1.300 + 0.419X (the inclination of occlusal plane was Y, and the mandibular deviation was X). CONCLUSIONS: Certain characteristics of mandibular symmetry and the occlusal plane were found in patients with high-angle skeletal class III malocclusion and jaw asymmetry. These findings provide references for doctors to pay attention to the degree and location of mandibular asymmetry and to determine the occlusal plane.