Investigation of Morphologic Changes in Temporomandibular Joint With Anterior Disk Displacement Based on 3-Dimensional Reconstructive Imaging

The objective of this study was to measure the association between the disk position and condylar alteration in patients diagnosed with anterior disk displacement (ADD) of temporomandibular joint (TMJ). A retrospective cross-sectional study was designed, dividing into 4 groups: normal articular disk position (NADP) of unilateral ADD patients (n=10), ADD with reduction (ADDwR, n=16), ADD without reduction (ADDwoR, n=24), and healthy volunteers (HV, n=30) based on magnetic resonance imaging and cone-beam computed tomography. After morphologic parameters were calculated from 3-dimensional reconstructive images, differences in parameters with respect to ADD status were tested with analysis of variance and Fisher least significant difference multiple comparisons were performed. Condylar volume of ADDwR, ADDwoR, NADP, and HVs were 1768.29±404.19, 1467.13±438.20, 1814.48±753.60, and 1914.66±476.48 mm, respectively, showing a significant downward trend from healthy disk to a displaced one ( P <0.05). Same trend also found in condylar superficial area, with the condylar superficial area of the ADDwR, ADDwoR, NADP, and HVs were 842.56±138.78 mm, 748.52±157.42 mm, 842.87±263.00 mm, and 892.73±164.19 mm, respectively. From NADP to ADDwR to ADDwoR, superior joint space (SJS) was declined, [SJS (NADP) (2.10±0.91 mm) > SJS (ADDwR) (1.85±0.61 mm) > SJS (ADDwoR) (1.50±0.50 mm), P =0.034]; medial joint space was significantly associated with the different disk displacement types ( P(HV-ADDwR) =0.001; P(HV-ADDwoR) =0.021; P(NADP-ADDwR) =0.022; P(ADDwR-ADDwoR) =0.001). Our findings suggest that condylar volume and superficial area, and superior and medial joint space, albeit with a small sample size, are significantly associated with different disk displacement types, detection of which might therefore be worth exploring for assessing ADD.