Diagnosis and management planning for root-filled teeth with persisting or new apical pathosis PAUL V. ABBOTT Teeth may require further management following root canal treatment because of persisting or new apical pathosis. Management must be based on the diagnosis of the presenting condition and the history of the previous treatment, particularly in relation to when it was completed. Most root-filled teeth with periapical pathosis should be re-treated in the first instance via a conventional orthograde approach since most disease is related to an infected root canal system. However, this approach to treatment should only be followed if the tooth is suitable for further restoration and when the restoration has a good long-term prognosis. Assessment of whether a tooth is suitable for treatment may not be possible until after restorations, caries, and cracks have been removed so that the remaining tooth structure can be visualized and assessed. Periapical surgery should be reserved for teeth with persistent symptoms and/or apical radiolucency following root canal re-treatment and where the differential diagnosis suggests an ongoing periapical condition such as a true cyst, extra-radicular infection, or foreign body reaction which cannot be addressed via an orthograde approach. If a tooth has to be extracted, it can be replaced with one of several forms of prostheses; implant-supported prostheses are gaining popularity and have a proven track record, especially for single tooth replacements. The use of implants should be restricted to cases where teeth are already missing or where a tooth cannot be retained because it is not suitable for further restoration due to insufficient tooth structure. Received 1 September 2009; accepted 24 October 2010. Introduction The first, and most important, stage of managing disease is to diagnose the presenting disease process. This requires the clinician to have a thorough knowl- edge and understanding of the disease processes. When assessing a patient who presents with symptoms and/or a periapical radiolucency associated with a root-filled tooth a number of factors must be consid- ered. In the past, the focus has often been placed on the radiographic appearance of the root filling, which has led to a mechanical approach to managing the disease. In this article, a biological approach will be outlined with emphasis on the diagnosis and then treating the cause in order to improve the predictability of the treatment outcome. In other words, the diagnosis should dictate the management options for the tooth. It is then a matter for the clinician and the patient to jointly decide which management option to choose. In order to diagnose any condition, it is necessary to have a classification of the various diseases and/or conditions which can occur. Classifications are im- portant because they:  allow clear and accurate communication between professionals;  allow clear and accurate education of students and colleagues;  help clinicians to categorize the presenting con- ditionFthat is, diagnose the conditionFwhich should then indicate the appropriate management options;  allow clear communication during scientific writing; and  avoid confusion between clinicians. 1 Endodontic Topics 2011, 19, 1–21 All rights reserved 2011 r John Wiley & Sons A/S ENDODONTIC TOPICS 2011 1601-1538