Research, Society and Development, v. 10, n. 3, e1510313023, 2021 (CC BY 4.0) | ISSN 2525-3409 | DOI: http://dx.doi.org/10.33448/rsd-v10i3.13023 1 Evaluation of the efficacy of XP-endo Finisher, Easy Clean, Passive ultrasonic irrigation, and conventional irrigation in the removal of calcium hydroxide in simulated internal root resorption cavities Avaliação da eficácia do XP-endo Finisher, Easy Clean, irrigação ultrassônica passiva e irrigação convencional na remoção de hidróxido de cálcio em cavidades de reabsorção internas simuladas Evaluación de la eficacia de XP-endo Finisher, Easy Clean, irrigación ultrasónica pasiva e irrigación convencional en la eliminación de hidróxido de calcio en cavidades de reabsorción interna simuladas Received: 02/16/2021 | Reviewed: 02/22/2021 | Accept: 02/24/2021 | Published: 03/03/2021 Gabriela Jorge Campos ORCID: https://orcid.org/0000-0002-2618-0367 Faculdade São Leopoldo Mandic, Brazil E-mail: jc.gabriela@gmail.com Carlos Eduardo Da Silveira Bueno ORCID: https://orcid.org/0000-0002-2675-0884 Faculdade São Leopoldo Mandic, Brazil E-mail: carlosesbueno@terra.com.br Rina Andrea Pelegrine ORCID: https://orcid.org/0000-0003-4175-2121 Faculdade São Leopoldo Mandic, Brazil E-mail: rinapelegrine@terra.com.br Ana Grasiela da Silva Limoeiro ORCID https://orcid.org/0000-0003-4633-720X Faculdade de Ilhéus, Brazil E-mail: grasielalimoeiro@gmail.com Carlos Eduardo Fontana ORCID: https://orcid.org/0000-0002-2868-6839 Pontifícia Universidade Católica de Campinas, Brazil E-mail: ceffontana@hotmail.com Homero Casonato Junior ORCID: https://orcid.org/0000-0002-1341-4363 Centro Universitário Hermínio Ometto, Brazil E-mail: homerojunior@fho.edu.br Alexandre Sigrist De Martin ORCID: https://orcid.org/0000-0002-3320-9172 Faculdade São Leopoldo Mandic, Brazil E-mail: a-sigrsit@uol.com.br Abstract This study aimed to evaluate the efficacy of 5 irrigation protocols in removing calcium hydroxide in simulated internal root resorption cavities. Eighteen extracted human teeth, upper anterior and uniradicular, were prepared up to size 50. The teeth were divided longitudinally, and internal root resorption cavities were made by acid demineralization using nitric acid. The same sample was submitted to the five irrigation protocols. The cavities and root canals were filled with Ultracal XS (Ultradent, South Jordan, UT, USA) and stored in an incubator at 37ºC for one week. Afterward, the irrigation protocols were carried out: XP-endo Finisher (XPF; FKG, La Chaux-de-Fonds, Switzerland), passive ultrasonic irrigation (PUI), Easy Clean (Bassi/Easy Equipamentos Odontológicos, Belo Horizonte, Brazil) with reciprocating movement (ECR), Easy Clean with continuous rotation (ECC) and conventional irrigation with a syringe (CI). The solutions used, 2.5% NaOCl, and 17% EDTA, were warmed. The total volume of irrigant used for each sample was 20 mL (10 mL of 2.5% NaOCl, 5 mL of 17% EDTA and 5 mL of distilled water). The amount of calcium hydroxide remaining in the internal resorption after irrigation was assessed using scores. The data were analyzed using the Pearson and Kruskal-Wallis (Dunn) tests. Significantly more calcium hydroxide was removed in the XPF group than all other sample groups (P < 0.0001). XPF was superior to the other methods tested to remove calcium hydroxide in teeth with simulated internal resorptions. Keywords: Dental pulp cavity; Endodontics; Root canal irrigation.