Abstract:

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<0101). Each of the 18 (3010%) patientswas iso- lated two different genotypes ofP. gingivalisatdifferenttooth sites. Compared our sequence resultswith the published nucleotides sequences in Genbank, the homology of PCR products ofP. gingivalis16SrDNA, prtC and fimA gene were from 98162% to 100%.Conclusion:The PCRassay developed in this studywere sensitive and specific. Itis suitable for clinical rapid identification ofP. gingivalisinfection. Some of the patients had different genotypes ofP. gingivalisinfection at different tooth sites which suggests thatone individual may be infectedwith 2 ormore strains ofP. gingivaliswith differentgenotypes that are originated from various contagious sources.

Key words: polymerasechainreaction, Porphyromonasgingivalis, chronicperiodontitis