Evidence-based periodontology -- Ethical Considerations in Periodontal Research -- Overview of Clinical Research Design Architecture -- The Randomized Clinical Trials Design -- Biases in periodontal research -- Measurement reliability in periodontal research -- Compliance considerations in clinical trial design -- Performing systematic reviews and meta-analyses -- Statistical versus clinical significance in periodontal research -- Clinical practice guidelines in periodontology -- Multilevel analysis: site-tooth-patient level -- Contemporary Concepts in the Diagnosis of Periodontal Disease -- A guide to diagnostic accuracy studies in periodontology -- Clinical trials principles for evaluation of antimicrobial drugs in periodontal disease treatment -- The Hawthorne effect -- Clinical trials principles for evaluation of antimalodour products -- Specific issues in clinical trials on the evaluation of genetic factors in the pathology of periodontal disease -- Indices currently used in periodontal research -- Specific issues in epidemiological studies of periodontal disease -- Assessing confounding and effect modification in research involving periodontal disease and systemic diseases -- Animal models in periodontal research.