Related Experiment Video
Updated: Aug 14, 2026

Effects of Mechanical Methods Used in Peri-implantitis Treatment on Implant Surface Decontamination and Roughness
Published on: March 14, 2025
Evidence-based dentistry: Part IV. Research design and levels of evidence
1Faculty of Dentistry, Sunnybrook and Women's College Health Sciences Centre, University of Toronto, Toronto, Ontario, Canada. susan.sutherland@swchsc.on.ca
Abstract:
Previous papers in this series on evidence-based dentistry have discussed the first 2 steps in seeking answers to clinical problems formulating a clear question and strategically searching for evidence. The next step, critical appraisal of the evidence, is made easier if one understands the basic concepts of clinical research design. The strongest design, especially for questions related to therapeutic or preventive interventions, is the randomized, controlled trial. Questions relating to diagnosis, prognosis and causation are often studied with observational, rather than experimental, research designs. The strongest study design should be used whenever possible. Rules have been established to grade research evidence. This paper, the fourth in the series, presents an overview of research methodology most commonly used in the dental literature.
Related Concept Videos
Nursing Interventions II: Selecting and Classifying the Nursing Interventions
Study Design in Statistics
Does aspirin reduce the risk of heart attacks? Is one brand of fertilizer more effective at growing roses than another? Is fatigue as dangerous to a driver as the influence of alcohol? Questions like these are answered using randomized experiments with proper...
Types of Biopharmaceutical Studies: Controlled and Non-Controlled Approaches
Non-controlled studies, commonly employed for initial exploration, lack a control group, rendering them susceptible to biases and external influences. In contrast, controlled...
Introduction to Epidemiology
Study Designs in Epidemiology
Observational studies are those where the researcher does not intervene but rather observes natural variations. They include cross-sectional, cohort, and case-control studies.
Hazard Ratio
For example, in a clinical trial evaluating a...