Morphologic Analysis of the Temporomandibular Joint Between Patients With Facial Asymmetry and Asymptomatic Subjects by 2D and 3D Evaluation: A Preliminary Study

Abstract

Signs and symptoms of temporomandibular joint (TMJ) dysfunction are commonly found in patients with facial asymmetry. Previous studies on the TMJ position have been limited to 2-dimensional (2D) radiographs, computed tomography (CT), or cone-beam computed tomography (CBCT). The purpose of this study was to compare the differences of TMJ position by using 2D CBCT and 3D model measurement methods. In addition, the differences of TMJ positions between patients with facial asymmetry and asymptomatic subjects were investigated. We prospectively recruited 5 patients (cases, mean age, 24.8 ± 2.9 years) diagnosed with facial asymmetry and 5 asymptomatic subjects (controls, mean age, 26 ± 1.2 years). The TMJ spaces, condylar and ramus angles were assessed by using 2D and 3D methods. The 3D models of mandible, maxilla, and teeth were reconstructed with the 3D image software. The variables in each group were assessed by t-test and the level of significance was 0.05. There was a significant difference in the horizontal condylar angle (HCA), coronal condylar angle (CCA), sagittal ramus angle (SRA), medial joint space (MJS), lateral joint space (LJS), superior joint space (SJS), and anterior joint space (AJS) measured in the 2D CBCT and in the 3D models (P < 0.05). The case group had significantly smaller SJS compared to the controls on both nondeviation side (P = 0.009) and deviation side (P = 0.004). In the case group, the nondeviation SRA was significantly larger than the deviation side (P = 0.009). There was no significant difference in the coronal condylar width (CCW) in either group. In addition, the anterior disc displacement (ADD) was more likely to occur on the deviated side in the case group. In conclusion, the 3D measurement method is more accurate and effective for clinicians to investigate the morphology of TMJ than the 2D method.

FIGURE 1

The 3D models of mandible, maxilla, and teeth of (A) asymptomatic subject, (B) patient with facial asymmetry. 3D = three-dimensional.

FIGURE 2

Measurements of the HCA: (A) on the horizontal CBCT image; (B) in the 3D model. 3D = three-dimensional; A = the anterior direction; CBCT = cone-beam computed tomography; HCA = horizontal condylar angle; L = the left direction; P = the posterior direction; R = the right direction.

FIGURE 3

Measurements of MJS, SJS, LJS, CCA, and CCW: (A and B) on the coronal CBCT image; (C and D) in the 3D model. 3D = three-dimensional; B = the bottom direction; CBCT = cone-beam computed tomography; CCA = coronal condylar angle; CCW = coronal condylar width; L = the left direction; LJS = lateral joint space; MJS = medial joint space; R = the right direction; SJS = superior joint space; T = the top direction.

FIGURE 4

Measurements of SRA, PJS, and AJS: (A and B) on the sagittal CBCT image; (C and D) in the 3D model. 3D = three-dimensional; A = the anterior direction; AJS = anterior joint space; B = the bottom direction; CBCT = cone-beam computed tomography; P = the posterior direction; PJS = posterior joint space; SRA = sagittal ramus angle; T = the top direction.