Microscopic cleanliness evaluation of the apical root canal after using calcium hydroxide mixed with chlorhexidine, propylene glycol, or antibiotic paste Juliana M. da Silva, MD, a Carlos V. Andrade Junior, b Alexandre A. Zaia, c and Oscar F. Pessoa, d Pará, Bahia, and São Paulo, Brazil FEDERAL UNIVERSITY OF PARÁ, STATE UNIVERSITY OF SOUTHWEST BAHIA, AND STATE UNIVERSITY OF CAMPINAS This study evaluated cleaning of the dentinal wall after removal of different calcium hydroxide pastes. Sixty- eight single-rooted teeth were prepared using the step-back technique and randomly divided into 4 groups according to medication used: Ca(OH)2 with 0.2% chlorhexidine solution (Group 1), Ca(OH)2 with propylene glycol (Group 2), Ca(OH)2 with antibiotic paste (ciprofloxacin, metronidazole) and distilled water (Group 3), and Ca(OH)2 with antibiotic paste and propylene glycol (Group 4). The samples were stored at 37°C and 100% relative humidity for 21 days. The medicaments were removed using 5 mL 1% NaOCl, instrumentation with master apical file, 5 mL 1% NaOCl, patency with the K-file #10, ultrasonic instrumentation, and 10 mL 17% EDTA-T. The specimens were analyzed using scanning electron microscopy and chemical analysis. The Kruskal-Wallis (= 5%) test showed that were no differences between the experimental groups when comparing Ca(OH)2 removal (P = .0951). The chi-square test (= 5%) indicated a predominance of Ca(OH)2 obstructing dental tubules in all groups. On the basis of the methodology applied, it was concluded that the apical dentine surface remained equally covered by Ca(OH)2, regardless of the vehicle used. (Oral Surg Oral Med Oral Pathol Oral Radiol Endod 2011;111:260-264) The ultimate goals of endodontic treatment are com- plete removal of bacteria, their by-products, and pulpal remnants from infected root canals, and the complete sealing of disinfected root canals. Intracanal medica- ments have been thought to be an essential step in killing the bacteria in root canals; however, in modern endodontics, shaping and cleaning may assume greater importance as means of disinfecting root canals. Nev- ertheless, if multiple-visit endodontic treatment is cho- sen, the use of calcium hydroxide (Ca[OH] 2 ) as an intracanal medicament is recommended. 1 Calcium hydroxide is the most widely used medica- tion because of its well-documented antibacterial activ- ity 2-4 and its capacity to promote apexification. 5,6 Its main mechanism of action is to raise the pH sufficiently so that few microorganisms are able to survive. 7 How- ever, there are some strains that are resistant to the use of this drug. 8,9 To improve its antimicrobial activity, Ca(OH) 2 has recently been used in association with chlorhexidine 10-13 and with various combinations of antibiotics; one example is a mixture of ciprofloxacin and metronidazole. 14-17 Ciprofloxacin is a bactericidal drug that acts by blocking bacterial DNA replication. Additionally, metronidazole has a specific selective toxicity for anaerobic bacteria as well as parasites. 18 To achieve the best performance from the filling material, it is necessary to clean the dentin wall of smear layers and debris as well as intracanal medica- tion. 19 If this medication is not completely removed, its presence on the dentin wall could compromise the cleanliness and permeability achieved by the final flush after root canal instrumentation. 20,21 Ca(OH) 2 placed inside the root canal has to be re- moved before obturating the canal to obtain satisfactory sealing. The presence of Ca(OH) 2 on dentin walls can affect the penetration of sealers into the dentinal tu- bules. 22-25 The most frequently described method for removal of Ca(OH) 2 from the root canal is instrumentation with the master apical file (MAF) in combination with co- pious irrigation with NaOCl and EDTA. 26 EDTA has the ability to chelate Ca(OH) 2 residues, which makes them easier to remove by irrigation. 23 EDTA plus so- dium lauryl ether sulfate (EDTA-T) is widely used as the best irrigant for cleaning away the smear layer, a Master’s in Dentistry, Federal University of Pará, Belém, Pará, Brazil. b Department of Endodontics, State University of Southwest of Bahia, Jequié, Bahia, Brazil. c Department of Endodontics, Piracicaba Dental School, State Uni- versity of Campinas, Piracicaba, São Paulo, Brazil. d Department of Endodontics, Federal University of Pará, Belém, Pará, Brazil. Received for publication Jun 4, 2010; returned for revision Aug 2, 2010; accepted for publication Aug 4, 2010. 1079-2104/$ - see front matter © 2011 Mosby, Inc. All rights reserved. doi:10.1016/j.tripleo.2010.08.016 260