Dental restorations for oral rehabilitation - testing of laboratory properties versus clinical performance for clinical decision making.

At the outset, the categories of physical, chemical, mechanical, biological and clinical properties of biomaterials are reviewed in terms of their definitions and relevant examples. Clinical performance for restorative materials is considered in terms of five crucial categories of factors (operator, design, materials, site and patient). Clinical performance assessment in actual clinical trials is described in terms of United States Public Health Service (USPHS) and modified USPHS categories of ratings collected from direct observations. Clinical failure analysis is characterized using reverse s-shaped curves to summarize longevity (failure or success) and clinical longevity for 50% failures (CL(50)) is defined. Actual practice effectiveness is demonstrated as being approximately one-half of clinical trial efficacy. Types of restorative dental material clinical trials are contrasted (longitudinal versus cross-sectional, short-term versus long-term, university-based versus practice-based research networks). Poor correlations between laboratory test values and clinical performance are explained. The need for risk assessment is emphasized. Evidence-based dentistry is defined in terms of available published information and precautions. At this point, the evidence base for clinical performance of biomaterials is scant.