en تخصصي Special كاربردي Applicable BACKGROUND<br> We aimed to detect the changes in nasalance, articulation errors, and speech intelligibility after bimaxillary orthognathic surgery in skeletal class III pa-tients.<br> METHODS<br> 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 advance-ment 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.<br> RESULTS<br> Eleven women (55%) and 9 men (45%) with a mean age of 31.95 &plusmn; 4.72 yr were enrolled. The mean maxillomandibular discrepancy was 6.15 &plusmn; 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).<br> CONCLUSION<br> The patients might show a normal articulation pattern and a modified nasalance feature, following maxillary advancement plus mandibular setback surgery. Bimaxillary, Orthognathic surgery, Nasalance, Articulation 8 14 http://wjps.ir/browse.php?a_code=A-10-466-17&slc_lang=en&sid=1 Hamide Ghaemi 100319475328460010040 100319475328460010040 No 1. Department of Speech Therapy, School of Paramedical Sciences, Mashhad University of Medical Sci-ences, Mashhad, Iran. Erfan Emrani 100319475328460010041 100319475328460010041 No Student Research Committee, Facul-ty of Dentistry, Mashhad University of Medical Sciences, Mashhad, Iran Ali Labafchi 100319475328460010042 100319475328460010042 No Student Research Committee, Facul-ty of Dentistry, Mashhad University of Medical Sciences, Mashhad, Iran Khashyar Famili 100319475328460010043 100319475328460010043 No 3. Department of Oral and Maxillofa-cial Surgery, Mashhad Dental School, Mashhad University of Med-ical Science, Mashhad, Iran. Haleh Hashemzadeh 100319475328460010044 100319475328460010044 No Department of Orthodontics, Tehran Dental School, Tehran University of Medical Science, Tehran, Iran Sahand Samieirad 100319475328460010045 100319475328460010045 Yes Oral and maxillofacial diseases re-search center, Mashhad University of Medical Sciences, Mashhad, Iran