Analysis of the infectious/endotoxic content of root canals of teeth with symptomatic and asymptomatic endodontic infections

The interior of root canals with the presence of necrotic pulp tissue establishes a complex and adequate ecological niche for the development of polymicrobial endodontic infections. In addition, it is fundamentally important to observe its inflammatory potential through levels of virulence factors such as lipopolysaccharide (LPS) and lipoteichoic acid (LTA). The objective of this study was to investigate the presence of specific microorganisms in root canals, and to evaluate the levels of LPS and LTA in cases of symptomatic necrotic teeth with associated abscess (GI) and in root canals of asymptomatic necrotic teeth (GII) during the endodontic treatment (ET). Twenty patients requiring endodontic intervention were selected with or without pain symptomatology. Microbiological, LPS and LTA samples were collected in different phases of endodontic treatment: before the chemical-mechanical preparation (CMP), after CMP, and after intracanal medication (ICM), 20 root canals and acute apical abscess. Culture method was used to evaluate the effectiveness of CMP and ICM in reducing microbial load. Nested-PCR was performed to investigate specific species of microorganisms in the different phases of endodontic treatment. Levels of LPS were measured by the Limulus Amebocyte Lysate (LAL) test. Enzyme-Linked Immunosorbent Assay was used for quantification of LTA. All data were tabulated and analyzed by different statistical tests. Endotoxin levels were higher in GI than in GII (p <0.05). CMP was effective in reducing the microbial load in both groups (p <0.05). In GII there was a significant reduction of LTA after CMP (p <0.05), whereas in GI the reduction was significant only after MIC (p <0.05). In GI, there was a reduction of LPS after CMP (p <0.05). In GII, the reduction was only significant after ICM (p <0.05). Enterococcus faecalis and Fusobacterium nucleatum were highly detected in cases of primary infection. LPS is present in higher levels in symptomatic cases and is associated with the presence of spontaneous pain. It was concluded that different species are detected in all stages of endodontic treatment. CMP is able to reduce microbial load, but not LTA, whose levels remain high even after ICM (AU)