Three-dimensional Reconstruction and Comparison of Temporomandibular Joint Space Volume Before and After Orthognathic Surgery in Patients with Skeletal Class III Malocclusion With Mandibular Deviation

Objective: To look into the association between the degree of deviation and the changing trend in the temporomandibular joint (TMJ) space volume after orthognathic surgery in patients with skeletal Class III malocclusion.Methods: Twenty patients having combined orthodontic-orthognathic treatment for skeletal Class III malocclusions with mandibular deviation were chosen, and craniofacial spiral CT was performed before (T0), two weeks after (T1), and six months after (T2) surgery. Using 3D volume reconstruction, further partitioning, and analysis of each domain's volume changes over time, the TMJ space volume is to be obtained. The differences in changes between groups A (mild deviation group) and B (severe deviation group) were examined to examine the impact of the degree of deviation on the TMJ space volume.Results: A statistically significant difference (P<0.05) existed between the postoperative TMJ space volume in group A and the preoperative overall, anterolateral, and anteroinferior space volume; the same difference also existed between the postoperative TMJ space volume in the NDS and the preoperative posterolateral, posteroinferior space volume. In group B, the postoperative TMJ space volume was statistically significant (P<0.05) compared with the preoperative total and anteroinferior space volume in the DS; the difference between the total volume of the T1 stage on the NDS and the total volume of the T0 stage was statistically significant (P<0.05). The two groups showed substantial differences in the space volume changes between the T1-T0 phase and the T2-T1 period.Conclusion: Patients with skeletal Class III malocclusion and mandibular deviation after orthognathic surgery see a change in the TMJ space volume. All patient types experience a largely consistent space volume change trend two weeks after surgery, and the degree of mandibular deviation is correlated with the intensity and longevity of the alteration.