Efficacy in vitro of instrumentation rotary with glycolic extract of propolis in neutralizing the toxic effects of lipotheicoic acid (LTA) from Enterococcus faecalis to induce production of cytokines (IL-1², TNF-± e IL-6) by macrophages

Abstract

Gram-positive bacteria release as an important virulence factor lipoteichoic acid (LTA), which is structurally and immunologically similar to lipopolysaccharide (LPS) of Gram-negative bacteria. The aim of this study is to evaluate the efficacy of rotary instrumentation with nickel-titanium instruments associated with glycolic extract of propolis and intracanal medications to neutralize the cytotoxic effects of LTA from Enterococcus faecalis in root canals, analyzing the production of proinflammatory cytokines (IL-1², TNF-± e IL-6) by macrophages (RAW 264.7). Will be used 36 single-rooted human teeth with standardized size of 16 mm. Root canals will be prepared until the instrument BR2 (25/0.04) and the specimens will be distributed on plates (n = 12). After sterilization (Co60 gamma radiation), will be performed three repeated inoculations every 24 hours, 10 ¼L of solution of E. faecalis LTA in root canals. After the root canals will be prepared with 5 NiTi rotary instruments (BioRaCe system), according to the manufacturer's specifications, the following sequence: BR3 (25/0.06), BR4 (35/0.04), BR5 (40/0.04); BR6 (50/0.04), and BR7 (60/0.02). It will be used a glycolic extract of propolis 12% as an irrigant in all specimens (n=36). Then be applied EDTA (3 min) and the specimens will be divided into three groups (n = 12) according to the dressing (MIC): A) calcium hydroxide with saline solution, B) 2% chlorhexidine gel (CLX ) C) + CLX calcium hydroxide. The MIC will remain for 14 days. In total, three collections will be made of the root canal: 1) immediately after instrumentation; 2nd) after EDTA, 3rd) after removal of the MIC. These samples will be used to verify if the treatment protocols have the ability to neutralize the cytotoxic effects of LTA. To this end, macrophages (RAW 264.7) will be activated with the samples collected from the root canals, and after 24 hours, the supernatants will be used to verify the production of cytokines (IL-1², TNF-± e IL-6) by enzyme immunoassay (ELISA). The results will be statistically analyzed (ANOVA and Tukey's test, 5%). (AU)