Efficacy of Twin-block appliance in Class II division 1 of adolescents:A systematic review

Objective: To evaluate the efficacy of Twin-block appliance in Class II division 1 of adolescents.Methods: Several electronic databases(PubMed,The Cochrane library,Embase,CBMdisk,CNKI,VIP)were searched.Abstract that appears to fulfill the initial selection criteria were selected by consensus and original articles were retrieved.Five Chinese journals were hand searched for possible missing articles.Randomized controlled trials(RCTs) that evaluate the efficacy of Twin-block appliance in Class II division 1 adolescents without any surgical intervention or syndromic characteristics were considered.A comparable untreated control group was required to factor out normal growth changes.The quality of included studies was evaluated according to Cochrane Reviewer's Handbook 4.2.6 Meta-analysis was performed by using RevMan 5.0.0 software.Results: Four RCTs including 289 patients were identified.The results of our meta-analysis showed a significant increase on SNB angle,Ar-Gn,Nasolabial angle and Labialmental fold compared with control group(P0.05).Whereas overjet,overbite,ANB angle and Ls-E had a significant decrease.In addition,SNA angle and Li-E didn't show statistical significant changes(P0.05).Conclusion: In Class II division 1 of adolescents,Twin-block appliance can effectively decrease their overjet,overbite,ANB angle,and induce anterior-posterior growth of mandible.The effect on restrain forward growth of the maxilla was unclear.More RCTs are required to evaluate the efficacy of Twin-block appliance.