Evidence-based dentistry involves defining a question focused on a patient-related problem and searching for reliable evidence to provide an answer. Once potential evidence has been found, it is necessary to determine whether the information is credible and whether it is useful in your practice by using the techniques of critical appraisal. In this paper, the fifth in a 6-part series on evidence-based dentistry, a framework is described which provides a series of questions to help the reader assess both the validity and applicability of an article related to questions of therapy or prevention.