Porphyromonas gingivalis FimA fimbriae have been classified into 6 genotypes (types I–V and Ib) based on the diversity of the
fimA genes encoding the fimbrial subunits. We investigated the prevalence of
fimA genotype in Japanese children. Dental plaque specimens were obtained from 400 subjects (age; 2 to 15 years), including 134 with healthy gingiva, 239 with gingivitis and 27 with periodontitis, and then analyzed by polymerase chain reaction.
P. gingivalis was detected in 1.5%, 10.0% and 29.6% of these subjects, respectively. Significant differences were observed with regard to
P. gingivalis infection among the groups [chi-squared analysis: gingivitis vs. healthy,
P < 0.01, odds ratio (OR) = 7.4; periodontitis vs. healthy,
P < 0.001, OR = 27.8]. In
P.
gingivalis-positive subjects with periodontitis, the most prevalent
fimA types were type Ib/type II combination (37.5%) and type IV (37.5%), followed by type II (25.0%), while type IV (33.3%) and type II (29.2%) were most often detected in those with gingivitis. Our results suggest that the presence of
P. gingivalis is associated with periodontal diseases, and that the type II, IV and Ib/II combination are the most common among
fimA genotypes. (J Oral Sci 54, 77-83, 2012)
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