Evidence-based esthetic dentistry.

Evidence-based clinical practice integrates the best available evidence with clinical expertise. This article presents a clinical case scenario and, using a four-step, evidence-based approach, demonstrates how to (1) ask an evidence-based question; (2) search MEDLINE for the best evidence; (3) critically appraise the evidence; and (4) apply the evidence to the patient. The procedure is demonstrated with the sample question, Does bleaching of bonded porcelain veneers increase marginal leakage? A MEDLINE search strategy was developed for synonyms of the key words that best identify the problem, the intervention, and the outcome. The synonyms were combined using the Boolean operator "or" to identify a "sensitive" (i.e., inclusive) universe of 140,000 journal articles. These categories were then combined using the Boolean operator "and" to identify the most "specific" (i.e., exclusive) four articles from among the 140,000. Finally, to find the best evidence, the articles were limited to "humans" and "randomized controlled trials." This identified one article. Critical appraisal of the limited data in this one article indicates that the methods are valid and statistically significant, but because of the methods employed, may not be clinically important. Evidence-based methods take one to the edge of the available information universe in about 15 minutes. The results can be both exhilarating and sobering. They can indicate the depth or limits of available information and suggest gaps in the knowledge-base that require further study. Most importantly, however, the results allow practitioners to communicate incisively and truthfully with patients and to make more informed clinical choices.