Which study design provides the highest level of evidence in evidence-based dentistry?

Correct answer: D. Systematic review and meta-analysis of RCTs

• A. Cross-sectional studies provide prevalence data but are limited by snapshot design and inability to establish causation.
• B. Case-control studies are retrospective observational designs; they rank lower in the evidence hierarchy.
• C. Expert opinion and case series are at the BOTTOM of the evidence hierarchy.
• D. Correct. Systematic reviews and meta-analyses of well-designed RCTs (randomized controlled trials) provide the highest level of evidence. They synthesize data from multiple high-quality RCTs with rigorous methodology to minimize bias.