Abstract: PURPOSE:To investigate the influence of functional splint therapy, a conservative treatment which stabilizes the relationship between the condylar head and glenoid fossa, on post-surgical relapse in patients with idiopathic condylar resorption (ICR). METHODS: Thirteen patients treated between 2008—2012, who underwent orthognathic surgery for mandibular advancement were included in this retrospective study. Patients were treated with conventional functional splint therapy for 7.5±1.5 months followed by orthognathic surgery. Cephalometric analysis and temporomandibular joint spaces on serial magnetic resonance images were measured prior to orthognathic surgery(T0), immediately post-surgery(T1), and at least 12 months follow-up(T2) for evaluation of the long-term stability. The differences of data between the two periods were compared using SPSS 22.0 software package. RESULTS: All patients obtained an aesthetic facial profile after orthognathic surgery and a normal occlusion after treatment. Normal protrusive and lateral excursion were presented. The mean advancement of the mandible immediately following surgery (Y axis-B, T1-T0) was (5.05±3.54)mm. No significant difference in temporomandibular joint space was found between T1 and T2(0.17±1.93). Y Axis - B was the only measurement changed, which showed sagittal positional change of the mandible, the mean backward movement of (T2-T1) was (-1.64±2.48)mm. Eleven out of 13 patients presented no post-surgical relapse or less than 2 mm of mandibular backward movement(84.6%), 2 out of 13 patients showed more than 2 mm of mandibular backward movement(15.4%). CONCLUSIONS: Patients who underwent functional splint therapy showed stable condylar position in condylar fossa. Functional splint therapy reduces post-surgical relapse in patients with ICR. Functional splint therapy may be of value in patients with ICR treated with orthognathic surgery combined orthodontics.

Key words: Functional splint, Idiopathic condylar resorption, Orthognathic surgery combined orthodontic treatment, Orthognathic surgery, Surgical relapse