title: Evaluating the Risk of Bias of a Study.
abstract: OBJECTIVE
  This first article of a series of 4 is aimed at guiding dental practitioners on how to evaluate the internal validity (risk of bias,) of randomized controlled trials (RCT). All RCT's contain different areas and potential sources of bias. Understanding risk of bias (ROB) will allow dental practitioners to improve the quality of dental treatments.
  
  
  METHODS
  The following areas of bias were elucidated: sequence generation, allocation concealment, blinding of participants and personnel, blinding of outcome assessment, incomplete outcome data, selective reporting, and "other bias". The reader determines the ROB level by evaluating the areas or potential source of bias in the first phase. Normally, ROB levels are classified as low, high and unclear ROB.
  
  
  RESULTS
  This article reported the concepts and methods of evaluation of ROB in several areas of an RCT. An RCT with low ROB in all evaluated areas gives the dental practitioners more certainty and confidence that a specific clinical procedure is in fact effective and relevant to the patient.
  
  
  CONCLUSIONS
  The information provided here may guide dental practitioners in the evaluation of ROB in an RCT. The correct evaluation of ROB may improve the quality of dental treatments.
authors.affiliation: Department of Periodontology and Operative Dentistry, Faculty of Dentistry, University of Münster, Waldeyerstraße 30, 48149 Münster, Germany. Electronic address: clovisfaggion@yahoo.com.
authors.forename: Clovis Mariano
authors.initials: CM
authors.lastname: Faggion
mesh_terms: D015982:Bias; D003729:Dental Care; D006801:Humans; D017063:Outcome Assessment, Health Care; D016032:Randomized Controlled Trials as Topic / Q000592:standards*; D012107:Research Design / Q000592:standards*; D012306:Risk
keywords: Internal validity; Randomized controlled trial; Risk of bias