Diagnostic CBCT images of 60 adult patients (120 TMJs) who visited the orthodontic clinic of Hallym University Sacred Heart Hospital were reviewed. The study protocol was approved by the Hospital Ethics Review Committee (IRB 2013-1130).
The subjects were 34 women and 26 men aged 20-40 years (mean age, 25.52±4.97 years) (Table 1). Patients were included if they did not have missing teeth except third molars, severe crossbite or openbite (overbite and overjet ≥ 0 mm), functional mandibular deviation due to occlusal interference, previous orthodontic treatment, clinical signs and symptoms of TMDs, previous TMD treatment, evident dental or facial asymmetry, congenital skeletal deformity such as cleft lip and palate, and history of trauma or general condition affecting the TMJ.
For imaging, the patient was seated with the head in the natural head position, eyes focused on a point at the same level in a mirror, and teeth in centric occlusion (maximum intercuspation). All scans were acquired with an Alphard VEGAunit (Asahi Roentgen, Kyoto, Japan) set at 80 kV, 5 mAs, 15-second scan time, and 0.39-mm3 voxel size. The exposure field was 200 mm in diameter and 179 mm in height. Images were transformed to DICOM (digital imaging and communications in medicine) format and three-dimensionally reconstructed and analyzed through OnDemand 3D Application software (Cybermed, Seoul, Korea).
The images were saved in C-mode and reoriented along the Frankfort horizontal plane on the basis of the right porion, right orbitale, and left orbitale. Both three-dimensional (3D) and cephalometric analyses were performed. The subjects were divided into three equal groups according to the angle formed by Sella-Nasion plane and mandibular plane (SN-GoMe): hypodivergent (SN-GoMe, < 22°), normodivergent (SN-GoMe, 22°-36°), and hyperdivergent (SN-GoMe, >36°) groups.
One orthodontist performed all the measurements as described by Rodrigues et al.4 (link),23 (link) Sagittal slices showing a clear view of the condyle and mandibular fossa with a clear continuous line of cortical bone were examined. The position of each condyle was determined by measuring the anterior, superior, and posterior joint spaces (Table 2, Figure 1). Depth of the mandibular fossa and angulation of the posterior wall of the articular tubercle were measured for identifying fossa morphology (Figure 1). Axial condylar morphology was assessed by measuring the maximum medio-lateral width, maximum antero-posterior width, and angle between the condylar axis and the midsagittal plane (condyle head angle) (Figure 2). Sagittal condylar morphology was classified as normal, flattened osteophytic, and unclassified (Figure 3); normally shaped condyles were subclassified as oval and round on the basis of their shape in the axial view (Figure 4).