Clinical and radiographic evaluations of root canal therapy indicated, that after correct patient selection endodontic therapy is technically feasible in most cases (even in posterior teeth). Only in few cases (3%) did symptoms of flare ups (5.4-13.4%) last for more than one week. This rate could be further reduced by additional measures, such as the local application of antibiotics and steroids. Long-term success rates for root canal therapy have been reported to range between 71 and 96%. The patient's age and the type of tooth affected had no effect on prognosis. Teeth with periapical resorptions displayed slightly lower success rates. Failures were primarily attributable to overfilling or inadequate instrumentation and/or filling. Root canal therapy should be part of an overall treatment plan including considerations of primary and secondary prevention as well as each patient's individual needs.