The Effect of Bimaxillary Orthognathic Surgery on Nasalance, Articulation Errors, and Speech Intelligibility in Skeletal Class III Deformity Patients

BACKGROUND We aimed to detect the changes in nasalance, articulation errors, and speech intelligibility after bimaxillary orthognathic surgery in skeletal class III patients. METHODS This double-blinded before and after quasi-experimental study was conducted in the Department of Maxillofacial Surgery, Qaem Hospital, Mashhad, Iran from Mar 2019 to Apr 2020. The main intervention was maxillary advancement with LeFort I osteotomy and mandibular setback surgery with bilateral sagittal split osteotomy (BSSO). The nasalance score, speech intelligibility, and articulation errors were evaluated one week preoperatively (T0), 1 and 6 months (T1, T2) postoperatively by a speech therapist. The significance level was set at 0.05 using SPSS 21. RESULTS Eleven women (55%) and 9 men (45%) with a mean age of 31.95 ± 4.72 yr were enrolled. The mean maxillomandibular discrepancy was 6.15 ± 1.53 mm. The mean scores of nasalance for the oral, nasal, and oral-nasal sentences were significantly improved postoperatively (P<0.001). Pre-operative articulation errors of consonants /r/, /z/, /s/ and /sh/ were corrected following the surgery. The percentage of speech intelligibility was significantly increased over time (P<0.001). CONCLUSION The patients might show a normal articulation pattern and a modified nasalance feature, following maxillary advancement plus mandibular setback surgery.