Periodontal aspects of osseointegrated fixtures supporting a partial bridge. An up to 6-years retrospective study.

The present paper reports on the use of osseointegrated titanium fixtures (Brånemark) in partially edentulous patients. The tissue reactions around 509 implants in 97 upper and 71 lower jaws of 146 consecutive patients, rehabilitated by means of partial bridges--supported by implants only (60%) or by the combination of teeth and implants (40%)--were observed longitudinally. The mean number of implants per bridge was 2.40 (range 1-5) for the upper jaw and 2.06 (range 1-5) for the lower jaw respectively. Before loading, a total of 23 fixtures were lost, 15 in the upper and 8 in the lower jaw. This loss could partially be correlated to per- and post-operative complications and to fixture characteristics (length, self-tapping or not). After a loading time of 30 months (range 2 to 77 months), 6 implants, 2 in the upper and 4 in the lower jaw, showed symptoms of non-integration. The cumulative failure rate for the individual fixtures after a 6-year period reached 5.7 and 6.5% for the upper and lower jaw, respectively. The mean annual marginal bone loss, scored on standardized radiographs, was 0.9 mm during the 1st year and 0.1 mm the following years. This loss in marginal bone height was equal in the upper and lower jaws and not related to the type of occlusal material of the bridges. The present data showed that the cumulative failure rate for Brånemark implants supporting partial bridges can be limited to 6% after a 6-year period, and that the radiographic bone loss is comparable with that found around fixtures supporting full bridges.