title: The evidence from systematic reviews and meta-analyses published in orthodontic literature. Where do we stand?
abstract: OBJECTIVE
  To analyse meta-analyses included in systematic reviews (SRs) published in leading orthodontic journals and the Cochrane Database of Systematic Reviews (CDSR) focusing on orthodontic literature and to assess the quality of the existing evidence.
  
  
  METHODS
  Electronic searching was undertaken to identify SRs published in five major orthodontic journals and the CDSR between January 2000 and June 2014. Quality assessment of the overall body of evidence from meta-analyses was conducted using the Grading of Recommendations Assessment, Development and Evaluation working group (GRADE) tool.
  
  
  RESULTS
  One hundred and fifty-seven SRs were identified; meta-analysis was present in 43 of these (27.4 per cent). The highest proportion of SRs that included a meta-analysis was found in Orthodontics and Craniofacial Research (6/13; 46.1 per cent), followed by the CDSR (12/33; 36.4 per cent) and the American Journal of Orthodontics and Dentofacial Orthopaedics (15/44; 34.1 per cent). Class II treatment was the most commonly addressed topic within SRs in orthodontics (n = 18/157; 11.5 per cent). The number of trials combined to produce a summary estimate was small for most meta-analyses with a median of 4 (range: 2-52). Only 21 per cent (n = 9) of included meta-analyses were considered to have a high/moderate quality of evidence according to GRADE, while the majority were of low or very low quality (n = 34; 79.0 per cent).
  
  
  CONCLUSIONS
  Overall, approximately one quarter of orthodontic SRs included quantitative synthesis, with a median of four trials per meta-analysis. The overall quality of evidence from the selected orthodontic SRs was predominantly low to very low indicating the relative lack of high quality of evidence from SRs to inform clinical practice guidelines.
authors: *Department of Orthodontics, University of Athens, Greece and Private Practice, Athens, Greece, d.koletsi@gmail.com.
authors: Despina
authors: D
authors: Koletsi
authors: Barts and The London School of Medicine and Dentistry, Queen Mary University of London, UK.
authors: Padhraig S
authors: PS
authors: Fleming
authors: Clinic of Orthodontics and Paediatric Dentistry, University of Zurich, Switzerland.
authors: Theodore
authors: T
authors: Eliades
authors: Department of Orthodontics and Dentofacial Orthopedics, Dental School/Medical Faculty, University of Bern, Switzerland, Private Practice, Corfu, Greece.
authors: Nikolaos
authors: N
authors: Pandis
mesh_terms: D018865:Dental Research / Q000592:standards; D055094:Evidence-Based Dentistry / Q000592:standards*; D006801:Humans; D008310:Malocclusion / Q000628:therapy; D009971:Orthodontics, Corrective / Q000592:standards*; D017594:Publication Bias