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The structural changes of pharyngeal airway contributing to snoring after orthognathic surgery in skeletal class III patients.

ABSTRACT: Two-jaw surgery including mandibular and maxillary backward movement procedures are commonly performed to correct class III malocclusion. Bimaxillary surgery can reposition the maxillofacial bone together with soft tissue, such as the soft palate and the tongue base. We analyzed changes of pharyngeal airway narrowing to ascertain clinical correlations with the prevalence of snoring after two-jaw surgery.A prospective clinical study was designed including a survey on snoring and three-dimensional (3D) computed tomography (CT) in class III malocclusion subjects before and after bimaxillary surgery. We conducted an analysis on changes of the posterior pharyngeal space find out clinical correlations with the prevalence of snoring.Among 67 subjects, 12 subjects complained about snoring 5 weeks after the surgical correction, and examining the 12 subjects after 6 months, 6 patients complained about the snoring. The current findings demonstrated the attenuation of the largest transverse width (LTW), anteroposterior length (APL), and cross-sectional area (CSA) following bimaxillary surgery given to class III malocclusion patients, particularly at the retropalatal level. The average distance of maxillary posterior movements were measured to be relatively higher (horizontal distance 3.9 mm, vertical distance 2.6 mm) in case of new snorers.This study found that bimaxillary surgery could lead to the narrowing of upper airway at the retropalatal or retroglossal level as well as triggering snoring in subjects with class III malocclusion. Based on the current clinical findings, we also found that upper airway narrowing at retropalatal level may contribute to increasing the probability of snoring and that polysonography may need to be performed before orthognathic surgery in subjects with class III malocclusion.

SUBMITTER: Park JE

PROVIDER: S-EPMC5544661 | biostudies-other | 2017 Dec

REPOSITORIES: biostudies-other

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Project description:BackgroundSeveral appliances have been used for correction of developing skeletal Class II, including different myofunctional appliances as Twin block (TB)as well as the new pre-fabricated Myobrace (MB) appliance. However, the effects of these devices on the pharyngeal airways have not been compared in the literature. Thus, the aim of this study was to compare the effects of two Class II correction appliances; TB and MB on the sagittal pharyngeal airway dimension (SPAD), including the nasopharyngeal airway area (NPAA), the oropharyngeal airway area (OPAA), and the laryngopharyngeal airway area (LPAA).MethodsThis is a two parallel arms randomized comparative clinical trial. Twenty-six children of 9-12 years with Skeletal Class II malocclusion due to mandibular deficiency and normal maxillary growth as confirmed by lateral cephalometric X-ray readings (ANB angle > 4° and SNB angle < 78) and Cervical vertebral maturational index (CVMI) 1 or 2 were randomly assigned into two equal groups. Group I: TB, Group II: MB (prefabricated functional appliance, Myofunctional Research Co., Australia). Lateral cephalograms were taken for all patients in both groups before treatment (T1) and after treatment (6 months later) (T2). The primary aim was to assess pre and post treatment changes in the SPAD in each group, and compare between the two study groups. The secondary aim was to evaluate the sagittal skeletal measurements such as the SNA, SNB, ANB, Wits appraisal, as well as vertical skeletal measurements represented by the Frankfurt-mandibular plane angle (FMA) measured pre- and post-treatment. The independent samples t-test was used to compare the two study groups, and the mean difference and 95% confidence intervals (CI) were computed. The paired samples t-test was used to compare various parameters between T1 and T2 within each group. The cutoff for significance was p-value < 0.05. Data were analyzed using IBM SPSS for Windows (Version 26.0).ResultsBy Comparing changes in airway measurements within each group, it was found that NPAA, OPAA, and LPAA increased significantly after treatment within each group of MB and TB. TB group showed significantly higher mean difference (T2-T1) in both NPAA and OPAA than MB group with 28.39 (± 56.75) and 40.46 (± 52.16) respectively. The increase in LPAA values was not statistically significant at (T2-T1) between both groups. Regarding skeletal changes, there was a significant increase in the SNB values between T1 and T2 within each group with 2.82 (± 3.32) for MB group and 3.79 (± 3.06) for TB group Moreover, there was a significant decrease in the ANB values between T1 and T2 within each group by 2.42 (± 2.70) for MB group and 3.06 (± 1.14) for TB group. Similarly, there was a significant decrease in the ANB values between T1 and T2 within each group by -2.13 (± 0.62) for MB group and - 2.46 (± 0.72) for TB group. No significant differences were found between both groups in SNA, SNB, ANB and Wits appraisal at p = 0.06, p = 0.45, p = 0.43 and p = 0.22 respectively. FMA did not show significant difference between T1 and T2 within each group, nor showed a significant mean difference between both groups at T2-T1.ConclusionsTB was more effective than MB in improving the upper (NPAA) and middle (OPAA) airways, while no difference was found regarding the lower airway (LPAA). Both TB and MB reduced the severity of developing skeletal class II due to mandibular retrognathism by forward posturing of the mandible. Thus, patients with airway problems would benefit more from TB than MB.

Project description:Study objectivesThe Sleep Apnea Multilevel Surgery (SAMS) trial found that modified uvulopalatopharyngoplasty with tonsillectomy (if tonsils present) combined with radiofrequency tongue ablation reduced obstructive sleep apnea (OSA) severity and daytime sleepiness in moderate-severe OSA. This study aimed to investigate mechanisms of effect on apnea-hypopnea index (AHI) reduction by assessing changes in upper airway volumes (airway space, soft palate, tongue, and intra-tongue fat).MethodsThis is a case series analysis of 43 participants of 51 randomized to the surgical arm of the SAMS trial who underwent repeat magnetic resonance imaging (MRI). Upper airway volume, length, and cross-sectional area, soft palate and tongue volumes, and tongue fat were measured. Relationships between changes in anatomical structures and AHI were assessed.ResultsThe participant sample was predominantly male (79%); mean ± SD age 42.7 ± 13.3 years, body mass index 30.8 ± 4.1 kg/m2, and AHI 47.0 ± 22.3 events/hour. There were no, or minor, overall volumetric changes in the airway, soft palate, total tongue, or tongue fat volume. Post-surgery there was an increase in the minimum cross-sectional area by 0.1 cm2 (95% confidence interval 0.04-0.2 cm2) in the pharyngeal airway, but not statistically significant on corrected analysis. There was no association between anatomical changes and AHI improvement.ConclusionsThis contemporary multilevel upper airway surgery has been shown to be an effective OSA treatment. The current anatomical investigation suggests there are not significant post-operative volumetric changes associated with OSA improvement 6-month post-surgery. This suggests that effect on OSA improvement is achieved without notable deformation of airway volume. Reduced need for neuromuscular compensation during wake following anatomical improvement via surgery could explain the lack of measurable volume change. Further research to understand the mechanisms of action of multilevel surgery is required.Clinical trialThis manuscript presents a planned image analysis of participants randomized to the surgical arm or the clinical trial multilevel airway surgery in patients with moderate-severe obstructive sleep apnea (OSA) who have failed medical management to assess change in OSA events and daytime sleepiness. https://www.anzctr.org.au/Trial/Registration/TrialReview.aspx?id=266019&isReview=true%20Australian%20New%20Zealand%20Clinical%20Trials%20Registry%20ACTRN12514000338662, prospectively registered on March 31, 2014.

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The structural changes of pharyngeal airway contributing to snoring after orthognathic surgery in skeletal class III patients.

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