[Colonization relationship between Porphyromonas gingivalis and Bacteroides forsythus in the infected root canals with chronic apical periodontitis].

Purpose: To detect the distribution of P. gingivalis and B. forsythus in the infected root canals from Chinese chronic apical periodontitis, and investigate the colonization relationship between them in the root canals.

Methods: P. gingivalis and B. forsythus in the root canal samples of thirty-eight teeth with chronic apical periodontitis from 31 subjects who were referred to the Sichuan University West China Dental Hospital for dental treatment were studied with a 16S rDNA-directed polymerase chain reaction method. Fisher's exact tset was used to detect B. forsythus in the infected root canals with or without P. gingivalis. OR was used to analyse the relationship between them.

Results: The prevalence in 38 teeth was 39.5% for P. gingivalis, and 26.3% for B. forsythus, respectively. Significant positive relationship was shown in the combination of P. gingivalis and B. forsythus (OR=12, P<0.05).

Conclusion: Both P. gingivalis and B. forsythus colonized in the root canals with chronic apical periodontitis and there was a positive relationship between P. gingivalis and B. forsythus in the infected root canal flora.