Level of evidence in endodontics: what does it mean?

Abstract

This review is a short summary of how the level of evidence in endodontics and endodontic research in particular is defined. The goal of this review is to help dentists and endodontists to become familiar with the evidence pyramid and thereby better evaluate the reliability of evidence on daily practices and choices in patient care. All medical treatment, including endodontic treatment, should be based on the best available evidence. In this review, the definition of evidence is presented and the different levels in the evidence pyramid are discussed with a special focus on endodontics. Much of the presently published endodontic research is done in vitro, which is regarded as the lowest level of evidence. However, it is important to understand that a low level of evidence does not mean that the research in itself is of poor quality or somehow unreliable. Instead, it means that one cannot draw conclusions from in vitro studies to clinical events with a high probability of accuracy. The in vitro results may be true, and often are, but more evidence from different types of studies such as case‐control and cohort studies and even randomized controlled trials is needed to increase the probability that the results obtained in research do in fact correctly reflect the real events, e.g. level of probability of healing after a specific type of treatment for a specific disease. This review also discusses why the highest level of evidence may be difficult to obtain for a variety of practical and ethical reasons, and why not all endodontic treatment needs to be based on information from randomized controlled trials and systematic reviews.