Coexistence of and increases biofilm virulence and periapical lesions in rats.

The present study utilized an dual-species biofilm model and an rat post-treatment endodontic disease (PTED) model to investigate whether co-infection of and would aggravate periapical lesions. The results showed that co-culturing yielded a thicker and denser biofilm more tolerant to detrimental stresses compared with the mono-species biofilm, such as a starvation-alkalinity environment, mechanical shear force and bactericidal chemicals. Consistently, co-inoculation of and significantly increased the extent of periapical lesions compared with mono-species infection. Specifically, coexistence of both microorganisms increased osteoclastic bone resorption and suppressed osteoblastic bone formation. The synergistic effects also up-regulated inflammatory cytokines including and . In summary, coexistence of and increased periapical lesions by enhanced biofilm virulence.