Efficacy Of Twin-block Appliance In Class â…¡ Division 1 Adolescents: A Systematic Review

Objective:To evaluate the efficacy of Twin-block appliance in Class II division 1 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 and relevant conference papers 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.Choose 10 hard and soft tissue indexes to evaluate the efficacy of Twin-block appliance.The methodology quality of included studies were evaluated according to Cochrane Reviewer's Handbook 4.2.6,and meta-analysis were performed by using RevMan 5.0.0 software.Results: 4 RCTs including 289 patients were identified.The results of our meta-analysis showed a significant increase on SNB angle,Ar-Gn,Nasolabial angle,Labialmental fold compared with control group(P<0.05).Whereas overjet,overbite,ANB angle,Ls-E had a significant decrease(P<0.05).In addition,SNA angle and Li-E didn't show statistical significant changes(P>0.05).Conclusions:In Class II division 1 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. The methodology quality of the research in this field was low.More RCTs are required to evaluate the efficacy of Twin-block appliance.