The decision to retain a tooth or to place an implant should be based on the probability of longterm success of one or other of the treatment modalities. However, the periodontological and implantological studies published on this subject only allow a limited direct comparison because of the heterogeneous definition of treatment success. From a clinical point of view, it makes sense to adopt a method in which five periodontal prognostic categories (very good, good, fair, poor and hopeless) are established, based on a combination of various parameters (e.g. attachment loss, furcation involvement, mobility). Teeth with a 'fair' prognosis or better can be treated by periodontal therapy and maintenance in the long term, with a high probability of success. For teeth with a 'poor' prognosis (50% to 75% attachment loss and/or inaccessible class II furcation involvement, class III furcation involvement and/or mobility class II), however, the recommendation is extraction and replacement with implants, when prosthetic anchorage is needed at the site. As a rule, extraction is the treatment of choice for teeth with a hopeless prognosis. Generally accepted guidelines on the definition of treatment success are required, so that the results of alternative treatment modalities can be compared directly and the treatment outcome rendered more predictable.
Keywords: dental implant, extraction, periodontal therapy, periodontitis, tooth retention