Imaging analysis of temporomandibular joint anatomy changes after intraoral condylectomy combined with orthognathic surgery

Abstract

To quantitatively analyze the changes of facial symmetry and temporomandibular joint structure at different periods after intraoral condylectomy combined with orthognathic surgery, and to evaluate the long-term stability after the operation. Spiral CT data of 10 cases treated by intraoral condylectomy combined with orthognathic surgery were collected, and then reconstructed by ProPlan software. Mark points were drawn on the 3D-images reconstructed immediately after the operation, and 6 months and 12 months after the operation. The measurements parameters included condylar axis angle in three dimensions, condylar-glenoid relative position and condylar facial morphology related indicators. The results were statistically analyzed by the consistency test and the variance of repeated measurement data. The facial asymmetry of the patients was corrected after operation, the height of the affected mandibular ascending ramus(T1: [67.81±6.95]mm, T2: [64.49±6.24]mm, T3: [63.05±7.07]mm)as well as the degree of pogonion deviation decreased(T1: [2.79±4.93]mm, T2: [0.37±4.20]mm, T3: [0.33 ± 3.97]mm)(P<0.05). But the tilt angle of the occlusion plane and the degree of mandibular height asymmetry had no significant difference between all the post-operative periods(P>0.05). The post-operative 3D changes of the position and shape of the resected and its contralateral condylar showed that the bilateral condylar axis angle in the horizontal plane gradually grew after operation(affected condyle: 71.95° ± 7.47°, 74.73°±8.44°, 76.56°±5.22°; control condyle: 72.60°±5.56°, 76.00°±5.30°, 77.19°±6.20° and had significant difference between all the post-operative periods)(P<0.05), the condyle moved slowly upward on both sides(superior space on the affected side: [8.78±4.38]mm, [4.11±2.49]mm, [3.27±1.96]mm; on the control side: [3.63±1.49]mm, [2.52±1.19]mm, [2.38±1.11]mm)(P<0.05), and moved inward only on the affected side(P< 0.05). All the above changes slowed down over time, and the disc-condyle-fossa relative position tended to be stable over time as well. The condyle diameter on the inside-outside direction gradually decreased on the affected side(T1: [14.98±2.39]mm, T2: [14.04±2.68]mm, T3: [13.74±2.89]mm)(P<0.05), and the surface morphology of the resected condyle was similar to the normal side. There were also some condylar surface morphological changes on the control side, but no statistical significance was found between different periods after the peration(P>0.05). The intraoral condylectomy combined with orthognathic surgery can eliminate condylar lesions effectively and correct the facial asymmetry caused by condylar benign tumor and hyperplasia. The facial symmetry can be maintained well after the operation, and the post-operative condylar morphology changes tended to be stable six months after the operation.