Efficacy of sodium hypochlorite, ethylenediaminetetraacetic acid, citric acid and phosphoric acid in calcium hydroxide removal from the root canal: a microscopic cleanliness evaluation Juliana Melo da Silva, MD, Amanda Silveira, Elizandra Santos, Laiìs Prado, and Oscar F. Pessoa, DDS, Belém, Brazil DEPARTMENT OF ENDODONTICS, FEDERAL UNIVERSITY OF PARÁ Rooted molars were subjected to standardized canal instrumentation to a master apical file (MAF). The samples were dressed with Ca(OH) 2 , and after 7 days, teeth were reopened and Ca(OH) 2 medication was removed by 1 of 4 different experimental procedures: 2.5% sodium hypochlorite (NaOCl) (n = 10); 17% EDTA-T (n = 10); 10% citric acid (n = 10); or 37% phosphoric acid (n = 10). This was followed by reinstrumentation with MAF plus 15 mL saline solution. The roots were prepared for scanning electron microscopic analysis of the cervical, middle, and apical thirds. Statistical analysis was performed with the Kruskal-Wallis test. EDTA-T and phosphoric acid gave the best results in the apical third, with significant statistical differences compared with other groups. NaOCl gave the worst results. Irrigation with 17% EDTA-T and 37% phosphoric acid is more effective than sodium hypochlorite and citric acid in the removal of calcium hydroxide from the apical third. (Oral Surg Oral Med Oral Pathol Oral Radiol Endod 2011;112:820-824) To achieve the best adaptation of filling material, it is necessary to clean the smear layer and debris from the dentin wall as well as give intracanal medication. 1 Calcium hydroxide medication is frequently used, be- cause 0.2% of the calcium hydroxide slurry dissoci- ates at body temperature into calcium ions (Ca 2+ ) and hydroxide ions (OH - ), leaving most of the particles undissolved. 2 The size and shape of the calcium hy- droxide particles may allow direct penetration into the open dentin tubules. 3 If this medication is not com- pletely removed, several studies have shown that the presence of calcium hydroxide on the dentin walls can affect the penetration of sealers into the dentinal tu- bules. 4-7 The removal of calcium hydroxide has been investigated using various products and techniques, such as chelants to dissolve the inorganic particles in the smear layer, and intracanal medications. 8 EDTA-T (EDTA plus sodium lauryl ether sulfate) is widely used as the best irrigant to clean the smear layer, mainly when it is associated with a cationic detergent, which allows better diffusion and effectiveness. 9,10 Another efficient irrigant that is used for the same purpose is citric acid, which is used at various concentrations. 11,12 For removal of Ca(OH) 2 the most frequently described method is instrumentation of the root canal with the master apical file (MAF) in combination with copi- ous irrigation by sodium hypochlorite (NaOCl) and EDTA. 13 However, it has been reported that the re- moval of Ca(OH) 2 from the root canal wall is diffi- cult 8,5,13 because instrumentation and irrigation alone cannot completely clean the entire area. 14 None of the above techniques is efficient at removing all the mate- rial from the canal walls, leaving up to 45% of the root canal surface covered with remnants. 8 The aim of the present study was to evaluate the efficacy of 2.5% NaOCl, 17% EDTA-T, 10% citric acid, and 37% phos- phoric acid in the removal of calcium hydroxide from the coronal, middle, and apical thirds of the human root canal system. MATERIALS AND METHODS Ethical clearance was obtained from the Ethical Committee (CEP-ICS/UFPA 190/08) of the Federal University of Belém, Pará, Brazil. Forty-eight distal and palatal rooted human molar teeth were used in this study. Preoperative mesiodistal and buccolingual radio- graphs were exposed for each root to confirm the canal anatomy. The criteria for tooth selection included: a single root canal, no visible root caries, fractures, or cracks, no signs of internal or external resorption or calcification, and a completely formed apex. Roots with 5° of curvature were considered to be straight and were in- cluded in this study. The teeth were decoronated to Received for publication Sep. 9, 2010; returned for revision Aug. 4, 2011; accepted for publication Aug. 6, 2011. 1079-2104/$ - see front matter © 2011 Mosby, Inc. All rights reserved. doi:10.1016/j.tripleo.2011.08.001 820