PURPOSE: Porphyromonas gingivalis fimA is a virulence factor associated with 
periodontal diseases, but its role in the pathogenesis of peri-implantitis 
remains unclear. We aimed to evaluate the relationship between the condition of 
peri-implant tissue and the distribution of P. gingivalis fimA genotypes in 
Koreans using a new primer.
METHODS: A total of 248 plaque samples were taken from the peri-implant sulci of 
184 subjects. The control group consisted of sound implants with a peri-implant 
probing depth (PD) of 5 mm or less with no bleeding on probing (BOP). Test group 
I consisted of implants with a peri-implant PD of 5 mm or less and BOP, and test 
group II consisted of implants with a peri-implant PD of more than 5 mm and BOP. 
DNA was extracted from each sample and analyzed a using a polymerase chain 
reaction (PCR) with P. gingivalis-specific primers, followed by an additional 
PCR assay to differentiate the fimA genotypes in P. gingivalis-positive 
subjects.
RESULTS: The Prevalence of P. gingivalis in each group did not significantly 
differ (P>0.05). The most predominant fimA genotype in all groups was type II. 
The prevalence of type Ib fimA was significantly greater in test group II than 
in the control group (P<0.05).
CONCLUSIONS: The fimA type Ib genotype of P. gingivalis was found to play a 
critical role in the destruction of peri-implant tissue, suggesting that it may 
be a distinct risk factor for peri-implantitis.