Retrospective assessment of clinical and microbiological factors affecting periimplant tissue conditions.

An increasing number of studies point to the detrimental effect of plaque bacteria on periimplant tissue health. The purpose of this retrospective study was to explore a possible relationship between the clinical and microbiological periimplant conditions of osseointegrated oral implants after several years of service and the dental and medical history, as well as the conditions of the residual dentition. 45 partially edentulous patients (mean age: 51 years, range: 27-83 years), with a total of 64 implants participated in this retrospective analysis. The time between examination and the last dental visit ranged from 6 to 24 months (mean: 13 months) and the time since the last maintenance therapy appointment with a dental hygienist ranged between 3 and 24 months (mean 7 months). During 5 to 10 years between implant installation and examination, 9 implants experienced one episode and an additional 6 implants two episodes of periimplantitis. As a consequence of extensive bone loss associated with these infections, one of these implants, in a patient who had a history of diabetes, was lost. With this exception, the other episodes of periimplantitis were successfully treated employing the principles of the Cumulative Interceptive Supportive Therapy (CIST) protocol. At examination, 42 implants (66%) showed a probing pocket depth exceeding 4 mm. Of the periimplantitis sites, four implants showed cultural evidence for presence of Porphyromonas gingivalis, and 2 implants were positive for Actinobacillus actinomycetemcomitans. Statistical analysis revealed a significant relationship between periimplant probing depth and the total anaerobic cultivable microbiota as well as the frequency of detection of P. gingivalis.