Abstract
Lipopolysaccharide (LPS) or endotoxin is the main virulence factor of Gram-negative bacteria and is able to stimulate cells to produce pro-inflammatory cytokines involved in periapical tissue destruction, while lipoteichoic acid (ATL) is one of the virulence factors of Gram-positive bacteria. Photodynamic therapy (PDT) is a complementary method of disinfecting the root canal (RC), in addi…