This study consist of three phases. In first step the objective is to develop a new chelating agent, with higher antiseptic capacity. In second step, the persistent bacteria that resist the endodontic treatment employing the better EDTA chelating agent of the first step will be measured by ATP-assay technique. In third step, will be analyzed the effects of stressed Enterococcus faecalis, in planktonic and biofilm form on cytokines production from macrophages. Methods: Step 1: 5 chelating agents will be tested. (N=10) Exp. 1:The smear layer production will be induced on dentin blocks and it reduction analyzed by MEV. Exp. 2 -The antimicrobial action of chelating agents will be tested for 5 minutes against Ent. Faecalis biofilm induced on dentin blocks and measured by confocal and bioimage programs. Exp. 3 - Dentin blocks will be treated with the chelating agents, after, the Ent. Faecalis adhesion to dentin was measured. Exp. 4 - Surface wettability was assessed using the sessile drop method. Exp. 5 - Bovine teeth filled with AH plus will have their roots sectioned, then the push-out test will be performed on the MTS 810 universal testing machine. Exp. 6 - Cytotoxicity will be evaluated by XTT reduction, neutral red and violet crystal evaluation. Step 2: Exp. 1 and 2 - Root canal and intratubular contamination will be make with Ent. Faecalis (N=10) . and treated with 5 protocols. After 3 months the evaluation of persistent micro-organisms will occur by ATP assay method. Step 3: Macrophages production of inflammatory cytokines stimulated by Ent. faecalis stressed on biofilm form will be measured by Elisa test.
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