Effects of mixtures of sodium hypochlorite with etidronate and alkaline tetrasodium EDTA associated or not with agitation methods on dentin structure and cleaning, debris extrusion, cell viability and tissue inflammation, and microbial biofilms

Abstract

The chelating agents etidronatic acid (HEDP) and alkaline tetrasodium EDTA (EDTANa4) were recently suggested as substitute for the EDTA in the smear layer removal. They have the advantage of being able to be used mixed with the sodium hypochlorite (NaOCl) during the biomechanical preparation of the root canal system without compromise the organic tissue dissolution and the antimicrobial action of the NaOCl. These chelators can exert antimicrobial effects if they are able to chelate metals that are essentials for the microbial metabolism and the biofilm stability. The EDTANa4 is available only for research use, however in the beginning of 2017 a commercial form of HEDP became available in Europe to be used in dental offices. Due to this, studies to evaluate the effects of their use associated or not with different agitation methods in several aspects of the endodontic treatment, such as dentin structure, tissue reaction and biofilm demetallization, are very relevant. Therefore, this project aims to: 1. Evaluate the effect of the mixtures of the HEDP and EDTANa4 with NaOCl associated with the agitation methods of passive ultrasonic irrigation (PUI), EndoActivator system and XP-endo Finisher on the dentin structure by Fourier-transformed infrared spectroscopy (FTIR) and scanning electron microscopy (SEM), in the calcium removal from dentin by atomic absorption spectroscopy (AAS), and in the removal and extrusion of debris from the instrumentation; 2. To evaluate the effect of HEDP, EDTANa4 and other irrigants in the cellular viability in cultures of NIH-3T3 e MC3T3-E1 cells, in the mineralization capacity, expression of cytokines genes by real-time polymerase chain reaction (RT-PCR) and in the MC3T3-E1 cells production of cytokines by Western blot; 3. To evaluate the inflammatory response in rat subcutaneous by staining with hematoxylin-eosin (HE), Masson's trichrome, Picrosirius Red and the cytokines production by immunohistochemistry after insertion of polyethylene tubes containing dentin debris mixes with the irrigants; and 4. To develop a methodology to evaluate the biofilms demetallization by chelating agents by confocal laser scanning microscopy (MCVL).