Methods: One hundred and ten patients (77 females and 33 males, aged 20 to 72 years; 14 smokers) and 232 implants were included. Sub gingival plaque samples were obtained at baseline, 3, 6, 9 and 12 months using paper points placed in the peri-implant sulcus. The samples were analyzed with DNA-DNA checkerboard hybridization and cultural techniques.
Results: The total bacterial count did not significantly change during the study (from 63x106 at baseline to 59x106 after 12 months). The microbiological analysis demonstrated a slight increase, however not significant, in the percentage of patients in which the presence of the most pathogenic bacteria ( P.gingivalis, T.forsythia and T.denticola ) could be detected (from 58.2%, 50.0%, and 47.3% respectively at baseline to 66.7%, 55.9%, and 52.9% after 12 months). The most frequently detected bacteria were F.nucleatum and P.intermedia (72.5% and 71.2% respectively) after 12 months without any significant difference compared to baseline.
Conclusions: The results of this prospective study suggest that pathogenic bacteria are present around implants in partially edentulous patients even within a short time after implant placement and that some microbiological conditions are susceptible to slightly change over time.