Randomized clinical trials (RCTs) and systematic reviews (SRs) in the context of evidence-based orthodontics (EBO)

Evidence-based orthodontics (EBO) should consider the best available scientific evidence, clinical expertise, and patient values and preferences during clinical decision-making. At the low end of the hierarchy of evidence is expert opinion, and at the higher levels, good-quality randomized clinical trials (RCTs), systematic reviews (SRs), and meta-analyses (MAs). Assessment and interpretation of the best-quality evidence requires training and skills that should be part of routine orthodontic education. This review article highlights important points that should be considered by the prospective EBO practitioner during critical appraisal of RCTs and SRs to inform clinical decisions. Concepts such as randomization, allocation concealment, blinding, risk of bias, intention-to-treat (ITT) and per-protocol (PP) analyses, effect estimates, confidence intervals, and subgroup analyses are explained, and their associations with RCT internal validity (methodological quality) and/or reporting quality are highlighted. The key steps during the systematic review process, sources of bias, and appropriateness of quantitative synthesis (meta-analysis) are outlined. Finally, the GRADE approach is introduced as a method for translating evidence into clinical practice.