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Clinical study on the effect of bimaxillary surgery on disc-condyle relationship of temporomandibular joint in patients with skeletal Class Ⅲ malocclusion
SONG Ming-yang, WANG Li-chan, WANG Yu-xin, ZHANG Qian, XIA Cheng-wan, WANG Si-qi, YANG Xu-dong
2025, 23 (1):
6-12.
doi: 10.19438/j.cjoms.2025.01.002
PURPOSE: To analyze the effects of orthognathic surgery on disk-condylar relationship of temporomandibular joint (TMJ) in patients with skeletal Class Ⅲ malocclusion. METHODS: Thirty patients with skeletal Class Ⅲ malocclusion who underwent Le Fort I osteotomy + bilateral mandibular sagittal split osteotomy in the Affiliated Stomatology Hospital of Nanjing University School of Medicine from April 2022 to April 2023 were selected. TMJ and mandibular movement data were obtained before surgery (T0), 3 months after surgery (T1) and at the end of postoperative orthodontics (T2). In addition, 20 patients with normal occlusion were selected as the control group, and the mandibular movement trajectories were recorded. SPSS 26.0 software package was used for statistical analysis of the data. RESULTS: Temporomandibular disorder (TMD) existed in 14 patients with skeletal Class Ⅲ malocclusion at T0, 8 of whom improved after surgery. At T0, the condylar relationship was normal on 18 sides, 42 sides were anterior displacements, of which 30 sides were anterior disc displacement with reduction(ADDwR) and 12 sides were anterior disc displacement without reduction(ADDwoR). Among the 12 sides of ADDwoR, 4 sides were transformed into ADDwR at T1 and 6 sides were transformed into ADDwR at T2. In the 30 sides of ADDwR, 6 sides returned to normal at T1, 1 side turned to ADDwoR, and 4 sides returned to normal at T2. In normal disk-condylar joint T1, ADDwR on 3 sides, ADDwoR on 1 side, and ADDwR on 2 sides at T2. After orthognathic surgery, the displacement angle of the anterior disk decreased in the normal group and the ADDwoR group, and increased in the ADDwR group. The maximum mouth opening at T1[(37.38±8.24)mm] was lower than that at T0 [(44.41±8.21)mm], and recovered to the preoperative level at T2 [(43.01±6.02)mm]. The symmetry of Bennett angle on both sides (|ΔBA|) was worse in T0 stage (6.27°±3.87°) than in the control group (3.43°±3.07°), and more symmetric in T1 stage (5.26°±7.21°) than in T0 stage, but there was recurrence tendency in T2 stage(9.97°±8.25°). The mandibular marginal movement, especially the range of backward movement at T0[(0.35±0.31)mm], was significantly smaller than that of the control group [(0.89±0.71)mm](P<0.05). The mandibular marginal movement at T1 was lower than that at T0. The condylar movement distances (CPL-L and CPL-R) of opening and closing mouth were significantly lower than those of T0(P<0.05), and the mandibular movement recovered or even exceeded the preoperative level at T2. CONCLUSIONS: In the short term after orthognathic surgery, the mandibular marginal movement decreases to some extent, but it will recover or even exceed the preoperative level in the long term. Orthognatology surgery can improve the TMD of skeletal Class Ⅲ patients, and has certain positive effect on predisc displacement.
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