Evaluation of Epoxy Resin Sealer After Three Root Canal Filling Techniques by Confocal Laser Scanning Microscopy DANIELA KOK, 1 MARCO ANTO ˆ NIO HU ´ NGARO DUARTE, 2 RICARDO ABREU DA ROSA, 1 * MA ´ RCIA HELENA WAGNER, 1,3 JEFFERSON RICARDO PEREIRA, 4 AND MARCUS VINI ´ CIUS REIS SO ´ 5 1 Rio Grande do Sul Federal University, Porto Alegre, Rio Grande do Sul, Brazil 2 Endodontics Department, Sa ˜o Paulo University, Bauru, Sa ˜ o Paulo, Brazil 3 Nursery and Dentistry Department, Santa Cruz do Sul University, Santa Cruz do Sul, Rio Grande do Sul, Brazil 4 Prosthodontic Department, University of Southern Santa Catarina, UNISUL, Tubara ˜ o, Santa Catarina, Brazil 5 Conservative Dentistry Department, Rio Grande do Sul Federal University, Porto Alegre, Rio Grande do Sul, Brazil KEY WORDS confocal laser scanning microscopy; endodontics; root canal filling ABSTRACT The aim of this study was to evaluate the penetration of endodontic sealer into the dentin tubules, the integrity of the sealer layer perimeter, and the sealer area at the apical third af- ter different filling techniques by confocal laser scanning microscopy (CLSM). Forty-five mandibu- lar premolars were mechanically prepared with ProTaper files, until F5 file. Thereafter, they were filled with an epoxy-resin sealer (AH Plus) mixed with Rhodamine B dye (0.1% proportion) and allocated in three groups: Group 1, single master cone; Group 2, cold lateral compaction; and Group 3, Thermafil. For confocal laser scanning microscopy analysis, the specimens were transversely sectioned at 4 mm from the apex. The images at 310 and 340 were analyzed by Imagetool 3.0 soft- ware. Significant differences were not found among the three experimental groups according the dentin-impregnate area by the sealer (P 5 0.68) and between the sealer and root canal perimeter (P 5 0.18). However, root canal filling techniques were significantly different when apical sealer areas were compared (P 5 0.001). Thermafil group showed smaller sealer areas (8.09%) while cold lateral compaction and gutta-percha master cone showed similar areas (17.37 and 21.18%, respec- tively). The dentin-impregnated area was not dependent on the root canal filling technique. Single master cone, cold lateral condensation and Thermafil techniques presented integrity of the sealer perimeter close to 100% and Thermafil resulted in a significantly thinner sealer layer. Microsc. Res. Tech. 00:000–000, 2012. V V C 2012 Wiley Periodicals, Inc. INTRODUCTION Endodontic sealer adaptation into the root canal walls plays an important role, due its physical barrier property, hampering microorganisms, and fluids infil- tration. These characteristics may contribute to the endodontic therapy failure (De Deus et al., 2002). Many studies about adhesiveness to dentin have been published. It has been showed that worst adhesiveness at the apical third of the canal can facilitate the marginal leakage (Hovland and Dumsha 1985). Resin-based sealers present suitable physic-chemical properties, such as appropriated setting time, flow, low viscosity, radiopacity >3 mm of aluminum, appropriate particle size and pH, and low superficial tension (Martin-Bauza et al., 2010). Sealer layer should be thin, homogeneous, and continuous to achieve great sealing ability (De Deus et al., 2003). The sealer layer thickness is important for the treatment success, espe- cially when it appears in thick layers, damaging the sealing capacity of the filling system (Bamiduro et al., 1992). It occurs due to the sealer solubility over time (Bamiduro et al., 1992). However, the presence of the sealer into the filling mass, do not guarantee gap-free root canal fillings (Hammad et al., 2009). There are no previous reports about the relationship between root canal filling techniques and penetrability of endodontic sealers into dentin tubules. The aim of this study was to evaluate the percentage of impreg- nated dentin area by resin-based sealer into dentinal tubules after three endodontic filling techniques by using confocal laser scanning microscope. Moreover, the sealer layer was evaluated according its area and integrity at the apical third of the canal. MATERIALS AND METHODS The study was approved by Ethical Committee of Rio Grande do Sul University (n 0 19356). Forty-five single rooted premolars, extracted for periodontal reasons, were used for this study. Teeth were disinfected in thy- mol crystal solution for 48 hours and stored at saline solution at 0.9%. -Root Canal Preparation Teeth were transversally sectioned with a diamond disc (KG Sorensen, Cotia, SP, Brazil) under water cool- ing to standardize the root size at 12 mm. The working *Correspondence to: Ricardo Abreu da Rosa, DDS, MSD, Rio Grande do Sul Federal University, 408 Gomes Carneiro Street, 97050470 Dores, Santa Maria, RS, Brazil. E-mail: rabreudarosa@yahoo.com.br Received 18 October 2011; accepted in revised form 20 March 2012 DOI 10.1002/jemt.22061 Published online in Wiley Online Library (wileyonlinelibrary.com). V V C 2012 WILEY PERIODICALS, INC. MICROSCOPY RESEARCH AND TECHNIQUE 00:000–000 (2012)