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The aim of this study was to evaluate tubular dentin sealer penetration, comparing different final irrigation protocols using a conventional needle (CONV), EndoActivator system (EAS), EndoVac system (EVS), and ultrasound (PUI). Initially, fifty-two first maxillary molars with a single canal in the palatal root, without abrupt curvatures, resorptive processes, or previous endodontic treatment were selected for this study. Then, the crowns were sectioned to obtain palatal roots 15 mm in length. The root canals were prepared with the ProTaper Universal System and irrigated with 5% NaOCl. Afterwards, the specimens were divided into four groups (n. 13), according to the final irrigation protocol: CONV, EAS, EVS, and PUI. After filling, slices at 3 mm and 5 mm from the apex were obtained for analysis by confocal laser scanning microscopy. Two-way comparisons between the groups and the levels were performed with Games Howell's test (p < .05). Tubular dentin sealer penetration was higher at 5 mm compared with 3 mm from the apex (p < .05). The EAS group showed a higher percentage of tubular dentin sealer penetration, compared with the CONV group, at both levels. At 3 mm, there was no statistically significant difference among EAS, EVS, and PUI; however, these groups showed better performance, compared with the CONV group. At 5 mm, there was no statistically significant difference between the EAS and EVS groups, but both showed higher sealer penetration than the PUI group (p < .05). The EAS and EVS groups achieved better degrees of tubular dentin sealer penetration, compared with the other groups.

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ResumoIntrodução: O hipoclorito de sódio é a substância química auxiliar do tratamento endodôntico mais utilizada devido à sua ação antimicrobiana e à sua capacidade de dissolver matéria orgânica. Objetivo: O objetivo do presente estudo foi comparar a velocidade de dissolução de fragmentos de tecido pulpar bovino em diferentes concentrações de hipoclorito de sódio. Material e método: Fragmentos de tecido pulpar bovino, com peso determinado, foram imersos em 20 mL de hipoclorito de sódio, em frascos de Becker colocados em uma incubadora/agitadora. Foram testadas as concentrações de 1%, 2,5% e 5%, com pH 11, a 36°C. As amostras foram avaliadas visualmente durante a agitação, com auxílio de lupa, até sua completa dissolução. A velocidade de dissolução de cada fragmento foi determinada em miligramas por minuto e a velocidade média de cada grupo, analisada pelos métodos estatísticos de Kruskal-Wallis e Dunn's Multiple. Resultado: Houve diferença estatisticamente significante entre a concentração de 1%, que apresentou a menor velocidade, e as demais. Conclusão: A velocidade de dissolução do hipoclorito de sódio, nas concentrações testadas, se torna mais rápida com o aumento da concentração.Descritores: Hipoclorito de sódio; dissolução; polpa dentária. AbstractIntroduction: sodium hypochlorite is the most used auxiliary chemical substance in endodontic treatment due to its antimicrobial action and its ability to dissolve organic matter. Objective: the objective of the present study was to compare the dissolution speed of bovine pulp tissue fragments in different concentrations of sodium hypochlorite. Material and method: bovine pulp tissue fragments, with determined weight, were immersed in Becker bottles filled with 20 ml of sodium hypochlorite and placed in an incubator/stirrer. Concentrations of 1%, 2.5% and 5%, with pH of 11, at 36°C. Each sample was evaluated visually during the stirring, with the aid of magnifying glass, until its complete dissolution. The speed of dissolution of each fragment was determined in milligrams per minute and by the average speed of each group was analyzed by Kruskal-Wallis and Dunn's Multiple statistical methods. Result: There were statistically significant differences between the concentration of 1%, with the lowest speed, and others. Conclusion: The dissolution speed of sodium hypochlorite of tested concentrations, becomes faster with the increasing of the concentration.Descriptors: Sodium hypochlorite; dissolution; dental pulp.

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