Evidence-Based Practice, Research Methods, and Ethics
What the exam tests
Critical appraisal, study design, biostatistics, and the ethical conduct of orthodontic practice and research.
Core rules
- The PICO question frames clinical evidence; the hierarchy runs from systematic reviews and RCTs down through cohort, case-control, and case series.
- Randomization, allocation concealment, and blinding reduce bias; intention-to-treat analysis preserves randomization.
- Confidence intervals convey precision; a p-value alone does not show clinical importance. Number needed to treat translates effect size into practice.
- Sensitivity and specificity describe a test; positive predictive value depends on prevalence.
- Reporting standards: CONSORT for trials, PRISMA for systematic reviews; register protocols and declare conflicts.
- Ethics: informed consent (including minors and assent), IRB approval, confidentiality of records, honest reporting, no fabricated data, and no misleading advertising or fee-splitting.
Worked example
A split-mouth RCT compares two adhesives: failure 5% versus 9%, p = 0.04, 95% CI for the difference 0.2–7.8%. Reasoning: the result is statistically significant but the absolute difference is small and the CI touches a trivial effect; cost, handling, and fluoride release may matter more than the 4% difference.
Traps
- Treating p < 0.05 as proof of clinical importance.
- Confusing sensitivity with positive predictive value.
- Ignoring dropout and intention-to-treat effects.
- Presenting promotional claims as evidence.