TMJ Condilar Changes After Bimaxillary Advancement and Disc Repositioning

Method: Thirty patients submitted to maxillo-mandibular advancement were divided in two groups: group 1 had no TMJ abnormality seen on MRI and received maxillo-mandibular advancement only. Group 2 had articular disc displacement on MRI and received bimaxillary surgery and TMJ disc repositioning simultaneously. CBCT scans were taken before surgery (T1), immediate after surgery (T2) and one year follow-up (T3). Image segmentation of the anatomic structures of interest and 3D graphic rendering were constructed using ITK-SNAP open-source software. Cranial base voxel-wise registration was used through the IMAGINE open-source software for accurate comparison of the three time point scans. Color-coded surface distances in millimeters were calculated by the CMF open-source software between T2-T1, T3-T2 and T3-T1. 

Result: Surface distance color-maps showed the location and quantified condylar displacements and/or remodeling. Both groups showed similar latero posterior and medio anterior condylar rotation after surgery and maintained this position 1 one post-surgery. Condylar surface post-surgical adaptive changes >2mm  occurred similarly in both groups, and no statistically  significant  differences  was  observed  between groups (p>0.05).

Conclusion: Patients with disc displacements treated with TMJ disc repositioning have similar condylar changes as experienced by patients with normal TMJ disc position after bimaxillary advancement.  Larger sample  size is needed to confirm our preliminary results.