Colonization by Porphyromonas gingivalis and Prevotella intermedia from teeth to osseointegrated implant regions

Colonization by periodontopathic bacteria is a risk factor for peri-implantitis. The purpose of this study was to investigate the colonization by black-pigmented anaerobic bacteria that occurs between the time before fixture installation and 6 months after inserting superstructures in implant treatment in partial edentulous cases. Dental plaque was serially collected from around the natural teeth and implants in 12 patients in whom a dental implant was indicated, and Porphyromonas gingivalis and Prevotella intermedia were detected using polymerase chain reaction (PCR). One month after connecting the abutment, the detection rate of P. gingivalis per site from around the implants was 63.7% and that of P. intermedia was 50.8%. Six months after superstructure setting, the detection rate per site of P. gingivalis from around the implants was 56.8% and that of P. intermedia was 41.1%. When chromosomal DNA segmentation patterns in the isolated P. gingivalis and P. intermedia were compared using pulsed field gel electrophoresis (PFGE), the patterns in the natural teeth were in accordance with those in the implants in 3 of 4 cases (75.0%) in P. gingivalis and all cases in P. intermedia. This finding suggested that bacterial colonization around implants occurred early after the implant region was exposed to the intraoral cavity and that the bacteria were transmitted from the area around the natural teeth.