Abstract: Objective To assess the evidences of Cochrane systematic reviews of orthodontic treatment for children and the methodological quality of all randomized and quasi-randomized controlled trials（RCT/qRCT） of the
included systematic reviews. Methods Issue 4, 2008 of the Cochrane Library was searched for systematic reviews on orthodontic treatments for children. All randomized or quasi-randomized controlled trials of Cochrane systematic
reviews of orthodontic treatment for children were evaluated. Results Four systematic reviews with twelve RCT were included. The included reviews were orthodontic and orthopaedic treatment for anterior open bite in children,
oral appliances and functional orthopaedic appliances for obstructive sleep apnoea in children, orthodontic treatment for prominent upper front teeth in children and orthodontic treatment for deep bite and retroclined upper front teeth in children. The risk of bias was assessed independently by two authors using the criteria which were described in the Cochrane Handbook for Systematic Reviews of Interventions 5.0.0. The methods of 9 studies were
rated of category C of the methodological quality with high risk of various bias. The methods of 2 studies were category A, and one study was category B. Conclusion Cochrane systematic reviews are received as the highest
quality of research evidences. There is insufficient, consistent evidence to support orthodontic and orthopaedic treatment for children. Further high quality RCT need to be conducted. To improve the quality of RCT reporting,
clinical trial registration and revised consolidated standards of reporting trial statement should be introduced into the trial design and strictly performed. Clinical evidence should be summarized in order to improve orthodontic
treatment for children.

Key words: orthodontics, systematic review, randomized controlled trial, methodology