Evaluation of horizontal condylar angle in malocclusions with mandibular lateral displacement using cone-beam computed tomography.

OBJECTIVES: To evaluate the horizontal condylar angle (HCA) in mandibular lateral displacement (MLD). MATERIALS AND METHODS: HCA in MLD malocclusions were examined using cone-beam computed tomography data in subjects with MLD and control subjects. RESULTS: HCA in joints of control patients and contralateral side joints of MLD patients were not significantly different. The mean HCA on the shifted side was larger than on the contralateral side (P < .001) in the different HCA groups. HCA was significantly larger on the shifted side than on the contralateral side in skeletal Class I, Class II, and Class III groups (P < .001). CONCLUSIONS: (1) There was no statistically significant difference between HCA in control patients and on the contralateral side in MLD patients. (2) HCA was significantly larger on the shifted side than on the contralateral side. (3) HCA on the shifted side and the contralateral side in MLD Class I, Class II, and Class III are significantly different.

Three-dimensional morphological characterization of malocclusions with mandibular lateral displacement using cone-beam computed tomography.

OBJECTIVE: The purpose of this study was to evaluate the morphologic characteristics of MLD malocclusions using 3D imaging. MATERIALS AND METHODS: MLD characteristics were examined using CBCT data in 40 subjects. A 3D Cephalometric analysis was developed to describe the spatial position of the mandible and temporal bones. RESULTS: Vertical dental heights were shorter and the posterior occlusal plane (POP) presented a steeper sagittal inclination on the shifted side (the side of the laterally displaced bony chin) than on the contralateral side. (p < 0.01). The MLD was related to a superiorly inclined POP Cant in the same direction (r = 0.82; p < 0.01). The shifted side condyle was dislocated medially and was smaller. Temporal bone sagittal inclination showed a more forward and medial inclination on the contralateral side (p < 0.01). CONCLUSIONS: A unilateral decrease in the vertical height of the dentition and the subsequent steeper occlusal plane inclinations correlated with (1) mandibular rotational displacement and condylar lateral displacement, (2) mandibular and condylar morphologic changes (3) changes in temporal bone position.

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.