Book excerpt: This book serves as a clinical guide to help the practitioner improve endodontic treatment outcomes. It focuses on the various factors affecting the prognosis of endodontic treatments and on their impact on short-term and long-term results. The text incorporates up-to-date knowledge, techniques and treatment protocols. Each chapter has been carefully chosen to address either foundational knowledge or a select aspect of endodontic treatment. The authors analyze the knowledge accumulated from a large number of outcome studies and provide the reader with a critical appraisal indicating the strengths and weaknesses of those studies. This information is then used to make recommendations on how to predict the outcome of the intended treatment. The authors emphasize that the endodontic prognosis is a multifactorial phenomenon, underscoring how various factors, singularly and in combination, influence the treatment outcome. Readers are provided with tools to successfully assess the prognosis of the proposed treatment at the outset and to execute the planned treatment focused on optimal outcome.