Sealer Penetration into Dentinal Tubules in the Presence or Absence of Smear Layer: A Confocal Laser Scanning Microscopic Study Astrit Kuc ¸i, DDS, PhD,* Tayfun Alac ¸am, DDS, PhD, † € Ozer Yavas ¸, DDS, PhD, † Zeynep Ergul-Ulger, MSc, ‡ and Guven Kayaoglu, DDS, PhD † Abstract Introduction: The aim of this study was to test the dentinal tubule penetration of AH26 (Dentsply DeTrey, Konstanz, Germany) and MTA Fillapex (Angelus, Lon- drina, PR, Brazil) in instrumented root canals obturated by using cold lateral compaction or warm vertical compaction techniques in either the presence or absence of the smear layer. Methods: Forty-five ex- tracted single-rooted human mandibular premolar teeth were used. The crowns were removed, and the root ca- nals were instrumented by using the Self-Adjusting File (ReDent-Nova, Ra’anana, Israel) with continuous so- dium hypochlorite (2.6%) irrigation. Final irrigation was either with 5% EDTA or with sodium hypochlorite. The canals were dried and obturated by using rhoda- mine B–labeled AH26 or MTA Fillapex in combination with the cold lateral compaction or the warm vertical compaction technique. After setting, the roots were sectioned horizontally at 4-, 8-, and 12-mm distances from the apical tip. On each section, sealer penetration in the dentinal tubules was measured by using confocal laser scanning microscopy. Results: Regardless of the usage of EDTA, MTA Fillapex, compared with AH26, was associated with greater sealer penetration when used with the cold lateral compaction technique, and, conversely, AH26, compared with MTA Fillapex, was associated with greater sealer penetration when used with the warm vertical compaction technique (P < .05). Removal of the smear layer increased the penetration depth of MTA Fillapex used with the cold lateral compaction technique (P < .05); however, it had no significant effect on the penetration depth of AH26. Conclusions: Greater sealer penetration could be achieved with either the MTA Fillapex–cold lateral compaction combination or with the AH26–warm verti- cal compaction combination. Smear layer removal was critical for the penetration of MTA Fillapex; however, the same did not hold for AH26. (J Endod 2014;-:1–5) Key Words Butterfly effect, epoxy resin, lateral condensation, mineral trioxide aggregate, thermo- plastic, warm gutta-percha E ndodontic treatment involves the removal of the vital and necrotic contents of the root canal through chemomechanical means followed by obturation of the prepared root canal to prevent ingress of fluids and avoid bacterial infection or regrowth. Me- chanical preparation of the root canal has been traditionally performed using stainless steel hand files and, within the past 2 decades, using rotary nickel-titanium (NiTi) files. A more recent advancement has been the introduction of the Self-Adjusting File (SAF; ReDent-Nova, Ra’anana, Israel), a compressible, thin-walled lattice made from a hollow 1.5- to 2.0-mm-sized NiTi cylinder, which is assumed to provide 3-dimensional clean- ing/shaping of the canal system through an oscillating mode of action (1). Among a variety of obturation techniques, cold lateral compaction stands as a practical and reliable technique; by using this technique, root canals can be filled effec- tively without sophisticated armamentarium, and length control can be successfully managed during compaction (2). On the other hand, warm gutta-percha (thermoplas- ticizing) techniques involve softening of the gutta-percha by using a heat source followed by either compacting inside or injecting into the canal of the softened gutta- percha material. Warm vertical compaction, an example of a thermoplasticizing technique, allows placement of a greater mass of gutta-percha in the canal, allowing for irregularities and accessory canals to be better filled compared with the cold lateral compaction technique (3, 4). Root canal sealers vary in composition and are used in conjunction with core filling materials (eg, gutta-percha cones) in order to fill the voids or irregularities in the root canal and to fill the space between the gutta-percha cones and between the core material and the dentinal wall. AH26 (Dentsply DeTrey, Konstanz, Germany) is a widely used epoxy resin–based sealer and possesses positive handling characteristics and superior physical properties (1). MTA Fillapex (Angelus, Londrina, PR, Brazil) is a new calcium silicate–based sealer containing mineral trioxide aggregate (MTA), salic- ylate resin, natural resin, bismuth oxide, and silica. The formulation is intended to benefit the advantages of MTA, a material known to possess favorable biocompatibility, antimicrobial activity, and good sealing ability (5). The smear layer is the organic and inorganic debris that forms after cavity prepa- ration or root canal instrumentation and coats the dentin and clogs the orifice of the dentinal tubules (6). Theoretically, this layer is assumed to prevent the penetration of disinfectants and root canal sealers into the dentinal tubules; therefore, its removal, by From the *Department of Dental Pathology and Endodontics, University Dentistry Clinical Center of Kosovo, University of Prishtina, Prishtina, Kosovo; † Department of Endodontics, Faculty of Dentistry, Gazi University, Ankara, Turkey; and ‡ Department of Biology, Faculty of Science, Ankara University, Ankara, Turkey. Address requests for reprints to Dr Guven Kayaoglu, Department of Endodontics, Faculty of Dentistry, Gazi University, 82 Sokak, 06510, Emek, Ankara, Turkey. E-mail address: guvenk@gazi.edu.tr 0099-2399/$ - see front matter Copyright ª 2014 American Association of Endodontists. http://dx.doi.org/10.1016/j.joen.2014.03.019 Basic Research—Technology JOE — Volume -, Number -, - 2014 Sealer Penetration into Dentinal Tubules 1