Objective:The purpose of this studywas to detect differentgenotypes ofPorphyromonas gingivalis (P.gingivalis)in subgin- gival plaque samples from patients with chronic periodontitis.Methods:The conventional culture method was used to isolate P. gingivalisfrom 127 subgingival plaque samples of 66 patients with chronic periodontitis. Coamplification of polymerase chain reaction was performed to detect 16SrDNA gene, the collagenase gene (prtC) and fibril gene (fimA) ofP. gingivalisfrom these clinical samples. Parts of the PCR products were TA cloned and then sequenced.Results:The positive rates ofP. gingivalis 16SrDNA, prtC and fimA gene coamplification by PCR in subgingival plaque sampleswere 9814%. PCRwere much more sensi- tive compared with the traditional method for detection ofP. gingivalis (P
