Clinical evaluation of the effect of different intracanal medications on levels of periapical resolvins and lipoxins: new endodontic perspectives

The aim of this study was to evaluate the effect of endodontic therapy using 2.5% NaOCl and intracane medications based on calcium hydroxide and Nacetyl cysteine (NAC) on root canal disinfection, reduction of endotoxins and stimulation of release of the lipid mediators Resolvin E1, D2 (RvE1, RvD2) and Lipoxin A4 (LxA4). Forty uniradicular teeth were selected, with primary endodontic infection and apical periodontitis. The teeth were randomly divided into 3 groups according to the intracanal medication to be used: G1: saline + Ca (OH) 2 (n = 14), G2: N-Acetyl Cysteine (n = 13), G3: chlorhexidine CLX) + Ca (OH) 2 (n = 14). Bacterial and endotoxin samples were collected from the root canal after coronary opening after preparation of the channels with reciprocal files (Reciproc) selected according to the root canal diameter and the irrigating solution (NaOCl 2.5%) and after intracanal medication. The analysis of the antimicrobial activity was by count of colony forming units (CFU / mL) of microorganisms remaining in the root canal and quantification of endotoxins (EU / mL) using the Limulus Amebocyte Lysate - LAL test. After biomechanical preparation (PBM) the teeth were filled with intracanal medications according to the groups for fourteen days. The interstitial fluid was collected after preparation of the channels and after 14 days of medication and quantification of the lipid mediators (RvE1, RvD2, LxA4) was performed through the enzymelinked immunosorbent assay (ELISA). The values obtained were tabulated, analyzed by GraphPad Prism 6.01 software and submitted to KolmogorovSmirnov and Lilliefors normality tests, followed by Kruskal-Wallis and Dunn and Anova one-way and Tukey tests (P <0.05). For microbial load, PBM reduced on average 96% of aerobic microorganisms and 92.5% of anaerobes in all groups (p <0.05). The use of intracanal medication based on Ca (OH) 2 maintained levels reached with PBM (p> 0.05), but in the NAC group there was an increase of bacteria. The endotoxin levels decreased after the preparation of the canals and the use of the medications reduced the endotoxin level, but without statistical difference in relation to the reduction achieved with the biomechanical preparation. As for the lipid mediators, only in the NAC group an increase of D2 Rv was observed. It was concluded that PBM significantly reduced the number of bacteria and the amount of endotoxins in the canal, and Ca (OH) 2-based medications were efficient in the elimination of microorganisms from the canal, however NAC was not effective for reducing the load microbial; The three medications evaluated were able to act on bacterial LPS. Only the NAC was able to positively influence this result with the increase of RvD2 after 14 days of the medication. Lipid mediators have great potential for use in various types of endodontic treatment. (AU)