Probabilities of success and failure in endodontic treatment: a Bayesian approach.

Bayes' theorem provides a mathematical rule for changing a (prior) probability into a new (posterior) probability incorporating additional information. Application of the theorem is a way to overcome some limitations that the human mind has in processing information. A Bayesian approach is useful for the processing of data and as a tool for decision making. Bayes' theorem is expounded, and examples are given of the use of the theorem for computing the odds on success or failure of endodontic treatment of a tooth, given a particular preoperative status and given also the results of the preparation and filling of the root canal of the tooth in question. Application of Bayes' theorem using data collected provides an insight based upon probabilities and odds in the way preoperative conditions and operative results affect the ultimate treatment result.