Bacterial plaque colonization around dental implant surfaces

PURPOSE: To examine the distribution of bacteria into the internal and external surfaces of failed implants using histologic analysis. MATERIALS AND METHODS: There were 10 failed pure titanium and 5 failed hydroxyapatite-coated titanium implants consecutively removed various years after their placement. Criteria for fixture removal were peri-implant radiolucency and clinical mobility. The mobile fixtures were retrieved with the patients under local anesthesia. Fixtures were removed maintaining the abutments with the aim to observe the bacterial infiltration at the level of abutment/implant interface and on the implant surface. RESULTS: A thin radiolucent space was always present around all the failed implants. The abutments screws were tightly secured in all clinical cases. The bacterial cells were composed of cocci and filaments, which were adherent to the implant surface with an orientation perpendicular to the long axis of the implant. All the specimens included in this study showed bacteria at the level of implant/abutment interface. CONCLUSIONS: Histologic analysis at the level of abutment/implant interface in 2-stage implants identified heavy bacterial colonization. These findings appear to support those studies showing bacteria penetration at the level of the micro-gap, which can legitimate the hypothesis that the micro-gap at the bone level could present a risk for bone loss caused by bacterial colonization.