Strains of Porphyromonas gingivalis, a periodontopathic bacterium, are 
classified into six genotypic variants based on nucleotide sequence differences 
in the fimA gene encoding FimA. A PCR assay using primer sets specific for each 
genotype has demonstrated that the most predominant fimA genotype in 
periodontitis patients is type II, which is now commonly referred to as the 
periodontitis-associated fimA genotype of P. gingivalis. However, the potential 
for false type II fimA positives caused by cross-hybridization of type II 
fimA-specific primers with type Ib fimA has complicated the genotyping. A 
previous study developed new primers that specifically amplified only the DNA 
fragment of type II fimA. The aim of the present study was to assess the 
prevalence of P. gingivalis fimA genotypes in Korean adults and to reconfirm the 
relationship between type II fimA and periodontitis using the new primers. Among 
412 Korean adults, P. gingivalis was detected in 97.5 % of patients and 57.8 % 
of healthy subjects. Type II fimA was the most widely distributed type among 
healthy and periodontitis subjects. Organisms with types II, Ib and IV fimA had 
a significant frequency of occurrence in periodontitis subjects. Statistical 
analysis, however, revealed that a more significant correlation was found 
between periodontitis and the occurrence of type Ib fimA.