Changes In Airway Dimensions Following Functional Appliances In Growing Patients With Skeletal Class ? Malocclusion:A Systematic Review And Meta-analysis

Objectives: The purpose of the study was to evaluate the treatment effects of functional appliances on upper airway dimensions in growing Class ? patients with mandibular retrognathism.Methods: Five databases(Medline(PubMed),EMBASE,Cochrane Library,Web of Science and Science Direct)and the references of identified articles were electronically searched for relevant studies that met our eligibility criteria.The last search was updated on Mar 14 th,2017.The main search terms included “functional appliances”,“malocclusion,angle class ?” and “airway”.The search strategy was modified appropriately in each database.We selected included studies according to the selection criteria.The quality of the included studies was assessed using the Newcastle-Ottawa Scale.The effects of functional appliances on airway dimensions were combined by meta-analysis using the RevMan and STATA software.Results: Our study finally included seven articles(177 treated patients with mean age: 11.48 years and 153 untreated controls with mean age:11.20 years).Compared to the control group,the oropharyngeal dimensions in the treatment group subjects were significantly increased at the superior pharyngeal space(MD = 1.73,95% CI,1.13-2.32,P < 0.00001),middlepharyngeal space(MD = 1.68,95% CI,1.13-2.23,P < 0.00001)and inferior pharyngeal space(MD = 1.21,95% CI,0.48-1.95,P =0.001).No significant differences were found in nasopharyngeal and hypopharyngeal dimensions and the position of hyoid bone(P > 0.05).Soft palate length and soft palate inclination were decreased significantly in the treatment group(P < 0.05).Conclusions: The results showed that functional appliances can enlarge the upper airway dimensions,specifically in the oropharyngeal region,in growing subjects with skeletal Class ? malocclusion.The early intervention for mandibular retrognathism with functional appliances may help enlarge the airway dimensions and decrease potential risk of obstructive sleep apnea syndrome for growing patients in the future.