Correlation Analysis Of The Effect Of Sagittal Split Of Mandible On Pharyngeal Cavity And Speech In Patients With Protruding Jaw

Background and ObjectiveJaw deformity is a developmental disorder of jaw bone caused by congenital or acquired factors such as heredity,disease and bad habits.It is one of the common diseases in maxillofacial surgery.The incidence of jaw deformity is very large.The incidence rate of this disease is about 14%[1]in Asian population.In the treatment of deviated jaw deformity,orthodontics and orthognathic joint treatment is generally used.Sagittal split of mandible is a common operation in orthognathic surgery.This operation can correct the facial deviation,biting disorder and other problems by adjusting the anatomical position of mandible,craniomaxillofacial soft and hard tissue,pharyngeal airway and so on.When sagittal split of mandible is used to correct the deviated jaw deformity,it will change the anatomical position of the tissues around the airway of pharyngeal cavity,but whether this change will affect the volume of pharyngeal cavity,and whether this effect has a long-term effect,whether this effect is related to the retrogressive distance of mandible,there are few studies on the above aspects.Human speech production is controlled by the nervous system and vibrated by the voice organs,and then transmitted through the cavity resonance and medium conduction of the body.Sagittal split of mandible can correct the deviated jaw deformity and affect the anatomical position of the voice organs such as hyoid,oral cavity and pharyngeal cavity resonance space.But whether this influence will cause the postoperative voice of patients There are few studies on functional changes and whether these changes are related to changes in pharyngeal volume.Therefore,the purpose of this study is to study and analyze whether the sagittal split of mandible can affect the volume of pharyngeal cavity and voice function at the same time of correcting the deviated jaw deformity,and further through the correlation analysis and research,analyze whether there is a correlation between the two in order to provide theoretical basis for guiding voice exercise of deviated jaw patients after operation and preventing iatrogenic OSAHS.MethodsAccording to the previous study,twenty patients were selected and included in the standard:(1)patients with skeletal Class Ⅲ partial process jaw(ANB<2°,The perpendicularity of POG-N is more than 5mm,the mandible is in the state of deflection measured by projection,and the submental point offset is more than 4mm).The SNA angle,UI/Sn angle and nasolabial angle of the upper jaw are basically normal.Only the sagittal split of the mandible can achieve the purpose and effect of the operation.(2)the growth and development of POG-N have been stopped,and the deformity of the simple development can be eliminated,such as trauma,cleft lip and palate and other congenital deformities,(3)Orthodontic treatment before and after operation is needed.The operation method is bilateral sagittal split osteotomy with decompensation treatment completed before operation.(4)the case data is complete.(5)the weight change before and 6 months after operation does not exceed 5kg.After orthodontic treatment,the patients were examined with cone beam computer tomography two days before operation and stored in DICOM format.The cone beam CT was taken again six months and one year after operation.The image data of DICOM were imported into mimics17.0 to reconstruct pharyngeal cavity,measure the volume of pharyngeal cavity in oropharyngeal and hypopharyngeal cavity before and after operation,and record the amount of mandible retrogression.SPSS 21 software was used to test the data for normality and homogeneity of variance.If the above conditions were met,ANOVA was used.If not,Wilcoxon rank sum test was used.The correlation between the volume change of pharyngeal cavity and mandible recession was analyzed by Spearman.In terms of speech research,refer to the previous research,use VS-99 computer speech workstation version 3.0 developed by Beijing Yangchen Electronic Technology and matching recording microphone and other related equipment to collect the vowel speech information of patients 2 days before operation and 6 months after operation,and measure the first three resonance peak frequencies(F1,F2,F3)before and after operation using SPSS The software kolomogorov smirno normal test was used for the data,paired t test was used for the data conforming to the normal,and signed rank test was used for the data not conforming to the normal.Finally,SAS 9.4 statistical analysis software was used to analyze the correlation between the volume changes of oropharyngeal and hypopharyngeal segments,and the changes of the first three formant frequencies(F1,F2,F3)before and after the operation.Results1.The volume data of pharyngeal cavity before and after operation were normal,but the variance was not homogeneous,so Wilcoxon rank sum test was used.The results showed that the volume changes of pharyngeal cavity,oropharyngeal cavity and hypopharyngeal cavity before operation,6 months after operation and 1 year after operation were different between groups.The volume of pharyngeal cavity,oropharyngeal cavity and hypopharyngeal cavity decreased in 6 months after operation and 1 year after operation The volume of oropharyngeal segment and hypopharyngeal segment increased more than that of 6 months postoperatively,but it was still less than the preoperative level(P<0.05).2.The volume reduction of pharyngeal cavity was positively correlated with the volume of mandible retrogression(r oropharynx=0.9 r hypopharynx=0.72 r total volume=0.84).The average volume of mandible retrogression was(9.2 ± 1.2)mm.3.Six months after the operation,when the vowel/a/formant frequency F1 and vowel/u/formant frequency F3 changed the non normal distribution,the sign rank test of paired data was needed.The result of the rank test showed that the difference was statistically significant(P<0.05)F1 and vowel/u/formant frequency F3 decreased significantly after operation.The peak frequencies of F1 and F2 of vowel/i/and F2 of vowel/u/accord with normal distribution.T-test of paired samples showed that the peak frequencies decreased significantly(P<0.05).4.The results of SAS 9.4 software correlation analysis showed that the change of oropharyngeal volume was significantly related to the change of vowel/i/formant frequency F2(P=0.04<0.05 r=0.5Conclusion1.The volume of oropharyngeal and hypopharyngeal pharyngeal cavity decreased after sagittal split osteotomy,which was positively related to the retrogressive distance of mandible,and may affect the postoperative ventilation function of patients.This effect has a gradual recovery trend.2.Sagittal split osteotomy of mandible can improve the vowel pronunciation of patients with skeletal class Ⅲ metagnathia.The volume change of oropharyngeal segment of pharyngeal cavity is closely related to some vowel changes.