Gene Polymorphism In RgpA And FimA Of Porphyromonas Gingivalis In Primary Endodontic Infections

Objective:To investigate the distribution difference of rgpA and fimA genotypes of Porphyromonas gingivalis(P.gingivalis)strains in primary endodontic infected root canals,and to analyze the association between the rgpA and fimA genotypes or their combined genotypes and symptoms of endodontic infections.Methods:A total of 141 samples from primary endodontic infected root canals were collected.DNA was extracted from the samples,P.gingivalis's 16S rRNA gene-based polymerase chain reaction(PCR)method was then applied to identify the appearance of P.gingivalis.Among the P.gingivalis-positive samples,we use 6 fimA gene-specific primers to detect the distribution of fimA genotypes by PCR.The rgpA gene-specific primer was also used to abtain rgpA gene segments by PCR.The gene polymorphism of rgpA was then evaluated by PCR-RFLP using the DNA restriction endonuclease Ava I.Pearson?~2 test was then performed to analyze the association between the genotypes and symptoms of endodontic infections.Results:Among the 141 samples,76(53.9%)samples were proved to be P.gingivalis-positive.rgpA gene was detected in 51(67.1%)samples,including 25(49%)cases of rgpA?genotype and 26(51%)cases of rgpA?genotype.fimA gene was detected in 62 samples(81.6%),including the fimA?genotype 20(32.3%)cases and the fimA?genotype 14(22.6%)cases were the two most frequently detected genotypes.A total of 46combined genotypes based on rgpA:fimA were detected,of which rgpA?:fimA?(19.6%)and rgpA?:fimA?(17.4%)combined genotypes were the two most frequently detected genotypes.Also,there was significant association between fimA?+?b genotype and the occurrence of pain.Among the rgpA:fimA combined genotypes,rgpA?:fimA?+?b can cause pain easily than rgpA?:fimA?+?b.Conclusion:The rgpA and fimA of P.gingivalis in primary endodontic infected root canals has genetic variations.There was significant association between fimA?+?b genotype and the occurrence of pain.