title: Little evidence to guide initial arch wire choice for fixed appliance therapy.
abstract: METHODS
  Medline, Cochrane Library, Biomed Central, BBO including LILACS, Ind Med, Sceilo, Clinical trials.gov, Conference paper Index, Digital Dissertations, German National Library of Medicine (ZB MED), Google Scholar, ISI Web of Knowledge, metaRegister of Controlled Trials, OpenSIGLE, Scirus.Study selectionTwo reviewers independently selected studies. Only randomised controlled trials (RCTs) and quasi-RCTs of parallel or split-mouth design were considered.
  
  
  METHODS
  Data abstraction and risk of bias assessment were carried out independently by two reviewers. Data were considered suitable for pooling if similar interventions were used in the same way and similar outcomes were reported. A random-effects model was used.
  
  
  RESULTS
  Sixteen studies involving 1108 patients were included. Thirteen trials (863 patients) considered initial archwires assessing cross-section of archwires, ion implantation of archwires and archwire materials.A meta-analysis of two trials found slightly greater irregularity correction with an austenitic-active nickel-titanium (NiTi) compared with a martensitic-stabilised NiTi archwire (corresponding to MD: 1.11 mm, 95% CI: 0.38 to 2.61).Four trials (394 patients) considered archwire sequences. A meta-analysis of two trials found it took patients treated with a sequence of martensitic-active copper-nickel-titanium (CuNiTi) slightly longer to reach the working archwire (MD: 0.54 months, 95% CI: -0.87 to 1.95 ; p= 0.45) compared with a martensitic-stabilised NiTi sequence. However, patients treated with a sequence of martensitic-active CuNiTi archwires reported general greater pain intensity on the Likert scale four hours and one day after placement of each archwire, compared with a martensitic-stabilised NiTi sequence.
  
  
  CONCLUSIONS
  There are insufficient data at present to make recommendations for the use of any available archwire type regarding effectiveness, efficacy, treatment outcome or potential side effects. The meta-analyses conducted are limited by the small number of trials and methodological issues and must therefore be subsequently confirmed.
authors.affiliation: Division of Orthodontics, Department of Dentistry, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, Canada.
authors.forename: Carlos
authors.initials: C
authors.lastname: Flores-Mir
mesh_terms: D003722:Dental Alloys / Q000737:chemistry*; D006801:Humans; D009969:Orthodontic Wires
chemical_list: D003722:Dental Alloys