Abstract:

Objective To investigate the impact of bilateral temporomandibular joint disc repositioning on mandibular morphology and position，and to analyze the relationship between postoperative changes in condylar position and condylar bone regeneration. Methods A retrospective study was conducted，including patients who underwent bilateral temporomandibular joint anterior disc displacement without reduction（ADDWoR） and disc repositioning surgery from April 2020 to December 2024. Preoperative（T0），1-month postoperative（T1），and more than 6-month postoperative（T2） cone beam computed tomography（CBCT） and magnetic resonance imaging（MRI） were measured using Materialise ProPlan CMF3.0 software. The evaluation indicators included the positional relationship of the mandible relative to the cranial base（e.g.，SNB，ANB），mandibular morphology（e.g.，mandibular ramus height，body length），condylar position（e.g.，anterior，superior，and posterior joint spaces），and condylar bone regeneration. The measurement results were analyzed using the Friedman test，Chi-square test，Fisher’s exact test，and Mann-Whitney U test. A P value<0.05 was considered statistically significant. Results Compared with T0，SNB increased significantly at both T1 and T2 （P<0.001），with no significant difference between T1 and T2 （P>0.05）. ANB，overjet，and the Pog-G' distance decreased significantly at T1 and T2 （P<0.001）. No significant differences were observed between T1 and T2 for ANB and Pog-G' （P>0.05）. The superior and posterior joint spaces increased significantly at T1 （P<0.001），then decreased significantly at T2 compared with T1 （P<0.001），but remained greater than at T0 （P<0.01）. Compared with T0，ramus height and mandibular body length increased significantly at T2 （P<0.05）. The proportion of condylar bone regeneration at T2 was 67.44% （58/86），distributed predominantly along the posterior slope，followed by the superior surface and the anterior slope.The highest regeneration rate occurred when the posterior-to-anterior joint space ratio was ≥1.5（P<0.05）. Conclusion Bilateral temporoman-dibular joint disc repositioning surgery effectively improves the disc-condyle relationship and induces adaptive changes in the morphology and position of the mandible and condyle. Postoperative condylar position reconstruction is associated with condylar bone regeneration，with an increased posterior-superior joint gap promoting condylar bone regeneration.

Key words: anterior disc displacement without reduction, disc repositioning surgery, mandibular morphology, condylar position, condylar bone regeneration