Abstract: Abstract: Objective To explore effects of the orthognathic surgery treating class Ⅲ osseous maxillofacial deformities on the patients′ voice function.Methods A total of 26 consecutive cases,who were diagnosed as class Ⅲ osseous maxillofacial deformities by orthodonticorthognathic associated therapy center of the affiliated stomatological hospital of Nanjing Medical University,were enrolled in this study.Those cases were divided into two groups according to the medical history and specialized examination.The cleft lip and palate group (Group A)included 10 cases.They were all congenital cleft lip and palate patients with secondary maxillary dysplasia.The other 16 cases diagnosed as developmental malformation alone were named none cleft lip and palate group (Group B).The voice information was collected before and one month after the surgery respectively.The statistic differences in voice intelligibility and first three formant frequencies of 6 vowels (/a/,/o/,/e/,/i/,/u/,/ü/) were analyzed.Results Group A,the voice intelligibility,the first and second formants of vowel /i/,and the second formant of /o/ and /u/ changed significantly(P ＜0.05);the decline degree of voice intelligibility was positively correlated with antedisplacement distance(r=0.8125).In Group B,the changes of voice intelligibility and every vowel′s formant were not significant after operation.Conclusions Orthognathic surgery treating class Ⅲ osseous maxillofacial deformities may exacerbate the degree of velopharyngeal incompetence for patients with secondary maxillary dysplasia,worsening their voice function.However,the surgery could be a compensation for the developmental malformation patients,delivering no significant impact.

Key words: class III osseous maxillofacial deformities, orthognathic surgery, velopharyngeal incompetence, voice intelligibility, frequency analysis