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.

The Effect of Bimaxillary Orthognathic Surgery on Voice Characteristics in Skeletal Class 3 Deformity Patients: An Evaluation Using Acoustic Analysis.

ABSTRACT: The aim of this study was to analyze the effects of bimaxillary orthognathic surgery on the acoustic voice characteristics of skeletal class 3 patients. All healthy nonsyndromic patients with Class 3 deformity who were eligible for bimaxillary orthognathic surgery, were included in this before and after quasi-experimental study. This experiment's main intervention was mandibular setback surgery by bilateral sagittal split osteotomy plus maxillary advancement using LeFort 1 osteotomy. Age, sex, and intraoperative jaw movements were recorded. Acoustic analysis of voice samples (vowels /a/ and /i/) was performed with Praat software as outcome variables. The formant frequencies (F0, F1, F2, and F3) of these vowels were extracted 1 week preoperatively (T0), 1 and 6 months (T1, T2) postoperatively by a speech therapist. The significance level was set at 0.05 using SPSS 19. The study sample comprised 20 patients including 11 women (55%) and 9 men (45%) with a mean age of 31.95 ±â€Š4.72 years. The average mandibular setback and maxillary advancement were 3.30 ±â€Š0.86 and 2.85 ±â€Š0.74 mm, respectively. The fundamental frequency (F0) and the first, second, and third formants (F1, F2, F3) of vowels /i/ and /a/ were significantly decreased over time intervals, postoperatively (P < 0.05). The finding revealed that bimaxillary orthognathic surgery (maxillary advancement and mandibular setback with bilateral sagittal split osteotomy) might reduce the acoustic formant parameters of voice to the normal frequency ranges, in patients with class 3 skeletal deformities. More clinical trials with greater sample sizes and long-term follow-ups are suggested in the future.