- Email: [email protected]
Penetration of Epiphany, Epiphany Self-Etch, and AH Plus into Dentinal Tubules: A Scanning Electron Microscopy Study
Basic Research—Technology
Penetration of Epiphany, Epiphany Self-Etch, and AH Plus into Dentinal Tubules: A Scanning Electron Microscopy Study Noushin Shokouhinejad, DDS, MSc,* Mohammad Sabeti, DDS, MA,† Hedayat Gorjestani, DDS, MSc,‡ Mohammad Ali Saghiri, BSc, MSc, PhD,§ Mehrdad Lotfi, DMD, MSc,k and Atefeh Hoseini, DDS¶ Abstract Introduction: The purpose of this study was to measure the average depth of dentinal tubule sealer penetration in the middle third of teeth obturated with gutta-percha/AH Plus (Dentsply, DeTrey, Konstanz, Germany), Resilon/ Epiphany (Pentron Clinical Technologies, Wallingford, CT), and Resilon/Epiphany self-etch (SE) using scanning electron microscopy (SEM). Methods: The root canals of 36 extracted single-rooted human teeth were prepared and randomly divided into three groups. Obturations were performed with the following filling materials using the lateral compaction technique: group 1, gutta-percha/ AH Plus; group 2, Resilon/Epiphany; and group 3, Resilon/ Epiphany SE. The specimens were prepared for SEM examination. The average depth of sealer penetration into the dentinal tubules was measured. Data were analyzed by one-way analysis of variance and a post hoc Tukey test. Results: The mean ( standard deviation) values for the average depth of sealer penetration in the middle third of the roots were 22.07 6.92 mm, 31.56 6.80 mm, and 21.50 9.25 mm for AH Plus, Epiphany, and Epiphany SE, respectively. The average penetration depth of Epiphany was significantly higher than that of Epiphany SE and AH Plus (P < .05). There was no significant difference between the penetration depth of Epiphany SE and AH Plus (P > .05). Conclusions: It could be concluded that the average penetration for Epiphany into dentinal tubules within the middle third of the roots was significantly deeper than that of Epiphany SE and AH Plus. (J Endod 2011;37:1316–1319)
Key Words AH Plus, Epiphany, scanning electron microscopy, sealer penetration, self-etch
T
he main goal of root canal therapy is two-fold: to eliminate microorganisms and their byproducts from the root canal system in addition to the prevention of reinfection. However, it is difficult or even impossible to eliminate completely all organisms from the canal space (1). The purpose of obturation is to eliminate leakage pathways from the coronal and apical directions and entomb remaining bacteria in the root canal system (2). The most commonly used material for root canal obturation is gutta-percha combined with a sealer. However, this approach does not provide a complete bacteria-tight seal of the root canal system (3, 4). Among the required physical properties of filling materials, adhesion was found to be a desirable property in root canal sealers (5). A resin-based adhesive material may have the potential to reduce the microleakage of the root canal because of its adhesive properties and penetration into dentinal walls (3). Resilon/Epiphany (Pentron Clinical Technologies, Wallingford, CT) is the first obturation system to claim the ability to form a ‘‘monoblock’’ between the canal walls and obturation material. Resilon is a polycaprolactone polymer that contains bioactive glass and radiopaque fillers. The first generation of the Epiphany obturation system consisted of a core material (Resilon), a dual-curing resin-based sealer (Epiphany), and a self-etching primer (3, 6). The second generation, new Epiphany self-etch (SE) soft resin endodontic obturation system, has been marketed consisting of two components: Epiphany self-adhesive (Epiphany SE; Parkell, Farmington, NY) sealer and Resilon. Acidic resin monomers that are originally found in SE primers have been incorporated into the self-adhesive resin-based sealers (eg, Epiphany SE, MetaSeal [Parkell], and RealSeal SE [SybronEndo, Orange, CA]) to make them advantageous. These types of sealers reduce the application time as well as errors during bonding steps (7, 8). Adhesive root-filling materials have been a matter of extensive research in the past few years (9). Although these materials may be advantageous in theory, some requirements need to be fulfilled (10). Several studies have compared the bond strength of gutta-percha and Resilon used in combination with different sealers to the root canal dentin (11–13). However, detailed information on adhesive properties of self-adhesive root canal sealers is limited because they are relatively new (8). The penetration of sealer cements into dentinal tubules is considered to be potentially beneficial. Sealer penetration increases the interface between material and dentinal walls; this may improve the mechanical retention of the material by interlocking of the sealer plug inside the tubules (14); this potentially reduces leakage (15).
From the *Department of Endodontics/Dental Research Center, School of Dentistry, Tehran University of Medical Sciences and Iranian Center for Endodontic Research, Tehran, Iran; †Department of Endodontics, University of Southern California, School of Dentistry, Los Angeles, California; ‡Oral and Dental Diseases Research Center, School of Dentistry, Kerman University of Medical Sciences, Kerman, Iran; §Department of Dental Material, Dental School, Azad University/Kamal Asgar Research Center (KARC), Tehran, Iran; kResearch Center for Pharmaceutical Nanotechnology and Department of Endodontics, Dental Faculty, Tabriz University (Medical Sciences), Tabriz, Iran; and ¶Private Practice, Shiraz, Iran. Supported by Tehran University of Medical Sciences and Health Services grant No. 12870. Address requests for reprints to Dr Mohammad Sabeti, PO Box 14374, Irvine, CA 92623. E-mail address: [email protected] 0099-2399/$ - see front matter Copyright ª 2011 American Association of Endodontists. doi:10.1016/j.joen.2011.05.002
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Basic Research—Technology Furthermore, the sealer’s antibacterial activity can be effective for killing and entombing bacteria that remain inside the dentinal tubules (16). The ability of sealer to penetrate dentinal tubules consistently and effectively is one of many factors influencing the choice of material for root canal filling (15). The penetration depth of epoxy resin-based sealers has been evaluated by some studies (15, 17). Furthermore, Patel et al (18) and Gharib et al (19) examined the penetration depth of the nonadhesive type of Epiphany and RealSeal into the dentinal tubules in extracted teeth filled with Resilon in combination with these resin-based sealers. To the best of our knowledge, there is no information about the penetration depth of the self-adhesive type of methacrylate resin-based sealers such as Epiphany SE into dentinal tubules. Therefore, this study was designed to compare the tubular penetration depth of AH Plus (Dentsply, DeTrey, Konstanz, Germany), Epiphany, and Epiphany SE.
Materials and Methods Thirty-six, extracted, human single-rooted premolars with straight canals were selected and stored in 0.5% chloramine-T before use. The crowns were removed to a standardized root length of 14 mm. A size 10 K-type file was inserted into the root canal until it could be seen through the apical foramen. The working length was established by reducing this length by 1 mm. The root canals were prepared using Mtwo Ni-Ti rotary instruments (VDW, Munich, Germany) according to the manufacturer’s instructions in the following sequence: (1) 10/.04, (2) 15/.05, (3) 20/ .06, (4) 25/.06, (5) 30/.05, and (6) 35/.04. NaOCl (5.25%) was used as the irrigant between files for a total of 5 mL. After completion of preparation, the root canals were irrigated with 5 mL of 17% EDTA for 1 minute and then finally rinsed with 10 mL of saline solution. All canals were dried with paper points; next, they were randomly divided into 3 groups of 12 teeth each as follows.
Group 1: Gutta-Percha/AH Plus In this group, the root canals were obturated with a size 35/0.02 gutta-percha (Gapadent Co, Ltd, Tianjin, China) master cone, which was coated with AH Plus sealer using cold lateral compaction technique. Accessory cones (size 20/0.02) coated with sealer were inserted into the canal until the entire root canal was filled. The excess guttapercha was removed with a heated instrument and then compacted vertically using a plugger. Group 2: Resilon/Epiphany Epiphany self-etching primer was introduced into the canal with a soaked paper point. After removing the excess primer with a dry paper point, a Resilon master cone (size 35/.02) was lightly coated with Epiphany sealer and placed into the canal to the working length. Lateral
compaction using accessory Resilon cones size 20/.02 was performed until the entire root canal was filled. The excess Resilon cones were removed with a heated instrument and then compacted vertically using a plugger. The coronal surface of the obturation was light-cured for 40 seconds to create an immediate coronal seal according to the manufacturer’s instructions.
Group 3: Resilon/Epiphany SE After mixing the Epiphany SE sealer on a mixing pad, Resilon master cone (size 35/.02) was lightly coated with Epiphany sealer and placed into the canal to the working length. The root canals were then obturated using a cold lateral compaction technique in the same manner as group 2. The quality of obturation was then confirmed radiographically. The root canal entrances were sealed with a temporary filling material (Coltosol; Coltene Whaledent, Mahwah, NJ). The specimens were stored at 37 C and 100% humidity for 7 days. After that, two longitudinal grooves were prepared on the buccal and lingual surfaces of each root using a diamond disc without penetration into the canal. The roots were then split into two halves with a chisel, producing two specimens per tooth (24 specimens per group). Because total sealer tags were impossible to count, four notches were made in each half using a scalpel: 4, 6, 8, and 10 mm apical to the most coronal level of the each root (18). Before scanning electron microscopic examination, the specimens were placed in 2% glutaraldehyde for 24 hours and then rinsed three times with sodium cacodylate-buffered solution (0.1 mol/L, pH = 7.2). After incubation in osmium tetroxide for 1 hour, the samples were dried for 24 hours. The specimens were then mounted on metallic stubs, gold sputtered, and examined with a scanning electron microscope (Leo 440i; Oxford Microscopy, Oxford, UK) that was equipped with a secondary electron detector (Fig. 1A). Digital images were recorded using a Microsoft picture manager (Redmond, WA) and processed with ImageJ program (Rasband WS, ImageJ; US National Institute of Health, Bethesda, MD) (Fig. 1B). Observations were performed at the dentin-sealer interface of the areas immediately apical and coronal to the notches and only on one side of the canal. The maximum penetration depth of the sealer into the dentinal tubules was measured in micrometers at the mentioned areas. Therefore, eight measurements were performed in each root half. These values were averaged to obtain a single observation for each root half. The data were analyzed by one-way analysis of variance and a post hoc Tukey test at a significance level of P < .05.
Results The mean ( standard deviation) values for the average depths of dentinal tubule sealer penetration in the middle third of the roots are
Figure 1. (A) An SEM micrograph at a higher magnification (3,000). (B) The image processed with ImageJ software. Arrows show sealer tags. JOE — Volume 37, Number 9, September 2011
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Basic Research—Technology TABLE 1. Penetration Depth of the Three Sealers (mm) Group
Sample size
Mean penetration ± standard deviation
1: Gutta-percha/AH Plus 2: Resilon/Epiphany 3: Resilon/Epiphany SE
24 24 24
22.07 6.92A 31.56 6.80B 21.50 9.25A
Values with the same superscript letter are not statistically different at P = .05.
shown in Table 1. The difference between these values was statistically significant (P = .028). The post hoc Tukey test revealed that the penetration depth of Epiphany was significantly higher than that of Epiphany SE and AH Plus (P < .05). However, there was no significant difference between the penetration depth of Epiphany SE and AH Plus (P > .05).
Discussion Removal of the smear layer is considered to be essential for root canal sealers to penetrate into dentinal tubules irrespective of the sealer used (20). Alternating the use of 5.25% NaOCl and 17% EDTA had been previously recommended for the effective removal of both the organic and inorganic components of the smear layer (21). The relevant literature shows a wide variety of irrigation times in removing the smear layer. The effectiveness of a 1-minute irrigation with 17% EDTA on smear layer removal has been shown (22). Therefore, in this study, EDTA was used for a short time (1 minute) to minimize destructive effects on dentin (23). Scanning electron microscopy has been used in several studies to evaluate the penetration of root canal sealers into the dentinal tubules (15, 17, 24–26). This technique provides a number of advantages. Scanning electron microscopic micrographs allow for observation of the dentinal tubules and accurate measurement of penetration depth of the sealers into dentinal tubules at a high magnification. In addition, it allows for the observation of sealer within dentinal tubules at distant sites from the root canal wall where the density of the tubules is lower. However, the inability to obtain a detailed overall view at low magnification is the main disadvantage of this technique. Furthermore, there is a potential for producing artifacts during the preparation of the specimens for SEM (15). Regional variation in the depth of sealer penetration has been shown by several authors (27, 28). The deepest penetration of sealer has been shown in the middle third of the root canal (24). Similar to Mamootil and Messer’s study (15), the sections evaluated in this study were representative of dentin from the middle thirds of the roots. Because AH Plus has been used in comparative studies of root canal sealers (29, 30), it was tested for comparison in this study. This study showed that the average penetration depth of Epiphany in the middle third of the root was significantly higher than that of the other sealers. This finding is partly in accordance with the results of the only study that compared the penetration depth of RealSeal (Epiphany) and Tubliseal (Kerr, Scafati, Italy), a sealer cement based on zinc oxide eugenol, and showed a significantly higher penetration depth for RealSeal (18). However, Patel et al (18) reported the mean penetration depth of RealSeal to be 914.88 mm in the middle third of the roots, which is different from the mean penetration value for Epiphany in this study (31.56 mm). The possible reasons for these conflicting results might be as follows: the methodology used to assess the sealer penetration depth could result in different findings. In the present study, the penetration depth was assessed using SEM, but confocal laser scanning microscopy (CLSM) was used in the study by Patel et al (18). Also, the controversial findings might be attributed to the mode of teeth sectioning, which was longitudinal in both studies. The whole dentin 1318
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surrounding the canal cannot be fully observed in longitudinal sections (14). Therefore, different values for sealer penetration could be obtained in various studies because there is potential to miss areas of deep penetration dependent on the location of the longitudinal section (15). Patel et al (18) measured the maximum penetration depth of the RealSeal on either side of the canal for each root half, but one side of the canals was evaluated in the present study. The result of this study for the average tubular penetration depth of Epiphany (31.56 mm) is not in accordance with the finding of Gharib et al (19). They assessed the horizontal root sections using CLSM and reported an average penetration depth of 538.1 mm for Epiphany in the middle third. These different results might be attributed to different modes of root sectioning (longitudinal vs horizontal) and different assessment methods (SEM vs CLSM). Different values for Epiphany penetration reported by Patel et al (18) and Gharib et al (19), which used CLSM, might be partly explained by the mode of root sectioning, which was longitudinal and horizontal, respectively. In addition, to facilitate fluorescence under confocal laser microscopy, the test subject is labeled with a fluorescent dye (19). In assessing the penetration depth of Epiphany, depending on the component labeled (primer, sealer, or both of them), the results might be affected. Patel et al (18) mixed RealSeal primer with the fluorescent dye, but Gharib et al (19) labeled the Epiphany sealer. This study showed that the average penetration depth of AH Plus into the dentinal tubules was 22.07 mm. Kokkas et al (17), in a study of longitudinal root sections using SEM, reported a mean maximum penetration depth of 54.6 mm for AH Plus, and their finding is quite consistent with our results. On the other hand, Mamootil and Messer (15), who evaluated the horizontal root sections using SEM, reported that the mean maximum penetration depth of AH26 (De Trey, Dentsply, Konstanz, Germany) was 1337 mm in the middle third. The penetration of root canal sealers into dentinal tubules might be influenced by variations in the physical and chemical properties of the sealers (31). Kokkas et al (17) revealed that AH Plus and Apexit (Vivadent; Ivoclaar, Schaan, Liechtenstein) sealers appeared to have a significantly greater maximum penetration depth in comparison with Roth 811 (Roth International, Chicago, IL). In addition, Mamootil and Messer (15) showed that there was a significant difference between the penetration depth of each of three different sealer cements: epoxy resin (AH26), zinc oxide eugenol (Pulp Canal Sealer EWT; Kerr, Sybron Dental Specialties, Romulus, MI), and methacrylate resin (EndoREZ; Ultradent Products, South Jordan, UT). The results of the present study revealed that the average penetration depth of the non-SE type of methacrylate resin–based sealer (Epiphany) was significantly higher than that of Epiphany SE. This difference might be attributed to the different composition of Epiphany and Epiphany SE. Acidic resin monomers incorporated into the self-adhesive resin-based sealers might influence the behavior of these sealers. In the present study, however, there was no significant difference between the penetration depth of Epiphany SE and AH Plus despite their different chemical composition. In conclusion, the average penetration depth of Epiphany into the dentinal tubules in the middle third of the roots filled with Resilon was significantly higher than that of Epiphany SE and AH Plus in roots filled with Resilon and gutta-percha, respectively. Although the penetration of root canal sealers into the dentinal tubules might be important from a clinical aspect, future studies should be considered to evaluate new root canal sealers in clinical situations.
Acknowledgments The authors deny any conflicts of interest related to this study. JOE — Volume 37, Number 9, September 2011
Basic Research—Technology References 1. Peters LB, Van Winkelhoff AJ, Buijs JF, Wesselink PR. Effects of instrumentation, irrigation and dressing with calcium hydroxide on infection in pulpless teeth with periapical bone lesions. Int Endod J 2002;35:13–21. 2. Siqueira JF Jr, R^oc¸as IN, Lopes HP, de Uzeda M. Coronal leakage of two root canal sealers containing calcium hydroxide after exposure to human saliva. J Endod 1999; 25:14–6. 3. Shipper G, Orstavik D, Teixeira FB, Trope M. An evaluation of microbial leakage in roots filled with a thermoplastic synthetic polymer-based root canal filling material (Resilon). J Endod 2004;30:342–7. 4. Shipper G, Teixeira FB, Arnold RR, Trope M. Periapical inflammation after coronal microbial inoculation of dog roots filled with gutta-percha or resilon. J Endod 2005; 31:91–6. 5. Tagger M, Tagger E, Tjan AH, Bakland LK. Measurement of adhesion of endodontic sealers to dentin. J Endod 2002;28:351–4. 6. Resende LM, Rached-Junior FJ, Versiani MA, et al. A comparative study of physicochemical properties of AH Plus, Epiphany, and Epiphany SE root canal sealers. Int Endod J 2009;42:785–93. 7. Babb BR, Loushine RJ, Bryan TE, et al. Bonding of self-adhesive (self-etching) root canal sealers to radicular dentin. J Endod 2009;35:578–82. 8. Kim YK, Grandini S, Ames JM, et al. Critical review on methacrylate resin-based root canal sealers. J Endod 2010;36:383–99. 9. Tay FR, Pashley DH. Monoblocks in root canals: a hypothetical or a tangible goal. J Endod 2007;33:391–8. 10. Ordinola-Zapata R, Bramante CM, Bernardineli N, et al. A preliminary study of the percentage of sealer penetration in roots obturated with the Thermafil and RealSeal-1 obturation techniques in mesial root canals of mandibular molars. Oral Surg Oral Med Oral Pathol Oral Radiol Endod 2009;108:961–8. 11. Gesi A, Raffaelli O, Goracci C, Pashley DH, Tay FR, Ferrari M. Interfacial strength of Resilon and gutta-percha to intraradicular dentin. J Endod 2005;31:809–13. 12. Sly MM, Moore BK, Platt JA, Brown CE. Push-out bond strength of a new endodontic obturation system (Resilon/Epiphany). J Endod 2007;33:160–2. 13. Ureyen Kaya B, Kececi AD, Orhan H, Belli S. Micropush-out bond strengths of gutta-percha versus thermoplastic synthetic polymer-based systems—an ex vivo study. Int Endod J 2008;41:211–8. 14. White RR, Goldman M, Lin PS. The influence of the smeared layer upon dentinal tubule penetration by plastic filling materials. J Endod 1984;10:558–62. 15. Mamootil K, Messer HH. Penetration of dentinal tubules by endodontic sealer cements in extracted teeth and in vivo. Int Endod J 2007;40:873–81. 16. Heling I, Chandler NP. The antimicrobial effect within dentinal tubules of four root canal sealers. J Endod 1996;22:257–9.
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17. Kokkas A, Boutsioukis A, Vassiliadis L, Stavrianos CK. The influence of the smear layer on dentinal tubule penetration depth by three different root canal sealers: an in vitro study. J Endod 2004;30:100–2. 18. Patel DV, Sherriff M, Ford TRP, Watson TF, Mannocci F. The penetration of RealSeal primer and Tubliseal into root canal dentinal tubules: a confocal microscopic study. Int Endod J 2007;40:67–71. 19. Gharib SR, Tordik PA, Imamura GM, Baginski TA, Goodell GG. A confocal laser scanning microscope investigation of the epiphany obturation system. J Endod 2007;33: 957–61. 20. Ordinola-Zapata R, Bramante CM, Graeff MS, et al. Depth and percentage of penetration of endodontic sealers into dentinal tubules after root canal obturation using a lateral compaction technique: a confocal laser scanning microscopy study. Oral Surg Oral Med Oral Pathol Oral Radiol Endod 2009;108:450–7. 21. Baumgartner JC, Mader CL. A scanning electron microscopic evaluation of four root canal irrigation regimens. J Endod 1987;13:147–57. 22. Moon YM, Shon WJ, Baek SH, Bae KS, Kum KY, Lee W. Effect of final irrigation regimen on sealer penetration in curved root canals. J Endod 2010;36: 732–6. 23. Tay FR, Gutmann JL, Pashley DH. Microporous, demineralized collagen matrices in intact radicular dentin created by commonly used calcium-depleting endodontic irrigants. J Endod 2007;33:1086–90. 24. Vassiliadis LP, Sklavounos SA, Stavrianos CK. Depth of penetration and appearance of Grossman sealer in the dentinal tubules: an in vivo study. J Endod 1994;20: 373–6. 25. Calt S, Serper A. Dentinal tubule penetration of root canal sealers after root canal dressing with calcium hydroxide. J Endod 1999;25:431–3. 26. Moradi S, Ghoddusi J, Forghani M. Evaluation of dentinal tubule penetration after the use of dentin bonding agent as a root canal sealer. J Endod 2009;35:1563–6. 27. Weis MV, Parashos P, Messer HH. Effect of obturation technique on sealer cement thickness and dentinal tubule penetration. Int Endod J 2004;37:653–63. 28. Sen BH, Pis¸kin B, Baran N. The effect of tubular penetration of root canal sealers on dye microleakage. Int Endod J 1996;29:23–8. 29. Sousa CJ, Montes CR, Pascon EA, Loyola AM, Versiani MA. Comparison of the intraosseous biocompatibility of AH Plus, EndoREZ, and Epiphany root canal sealers. J Endod 2006;3:656–62. 30. Versiani MA, Carvalho-Junior JR, Padilha MI, Lacey S, Pascon EA, Sousa-Neto MD. A comparative study of physicochemical properties of AH Plus and Epiphany root canal sealants. Int Endod J 2006;39:464–71. 31. Oks¸an T, Aktener BO, Sen BH, Tezel H. The penetration of root canal sealers into dentinal tubules. A scanning electron microscopic study. Int Endod J 1993;26: 301–5.
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Penetration of Epiphany, Epiphany Self-Etch, and AH Plus into Dentinal Tubules: A Scanning Electron Microscopy Study Noushin Shokouhinejad, DDS, MSc,* Mohammad Sabeti, DDS, MA,† Hedayat Gorjestani, DDS, MSc,‡ Mohammad Ali Saghiri, BSc, MSc, PhD,§ Mehrdad Lotfi, DMD, MSc,k and Atefeh Hoseini, DDS¶ Abstract Introduction: The purpose of this study was to measure the average depth of dentinal tubule sealer penetration in the middle third of teeth obturated with gutta-percha/AH Plus (Dentsply, DeTrey, Konstanz, Germany), Resilon/ Epiphany (Pentron Clinical Technologies, Wallingford, CT), and Resilon/Epiphany self-etch (SE) using scanning electron microscopy (SEM). Methods: The root canals of 36 extracted single-rooted human teeth were prepared and randomly divided into three groups. Obturations were performed with the following filling materials using the lateral compaction technique: group 1, gutta-percha/ AH Plus; group 2, Resilon/Epiphany; and group 3, Resilon/ Epiphany SE. The specimens were prepared for SEM examination. The average depth of sealer penetration into the dentinal tubules was measured. Data were analyzed by one-way analysis of variance and a post hoc Tukey test. Results: The mean ( standard deviation) values for the average depth of sealer penetration in the middle third of the roots were 22.07 6.92 mm, 31.56 6.80 mm, and 21.50 9.25 mm for AH Plus, Epiphany, and Epiphany SE, respectively. The average penetration depth of Epiphany was significantly higher than that of Epiphany SE and AH Plus (P < .05). There was no significant difference between the penetration depth of Epiphany SE and AH Plus (P > .05). Conclusions: It could be concluded that the average penetration for Epiphany into dentinal tubules within the middle third of the roots was significantly deeper than that of Epiphany SE and AH Plus. (J Endod 2011;37:1316–1319)
Key Words AH Plus, Epiphany, scanning electron microscopy, sealer penetration, self-etch
T
he main goal of root canal therapy is two-fold: to eliminate microorganisms and their byproducts from the root canal system in addition to the prevention of reinfection. However, it is difficult or even impossible to eliminate completely all organisms from the canal space (1). The purpose of obturation is to eliminate leakage pathways from the coronal and apical directions and entomb remaining bacteria in the root canal system (2). The most commonly used material for root canal obturation is gutta-percha combined with a sealer. However, this approach does not provide a complete bacteria-tight seal of the root canal system (3, 4). Among the required physical properties of filling materials, adhesion was found to be a desirable property in root canal sealers (5). A resin-based adhesive material may have the potential to reduce the microleakage of the root canal because of its adhesive properties and penetration into dentinal walls (3). Resilon/Epiphany (Pentron Clinical Technologies, Wallingford, CT) is the first obturation system to claim the ability to form a ‘‘monoblock’’ between the canal walls and obturation material. Resilon is a polycaprolactone polymer that contains bioactive glass and radiopaque fillers. The first generation of the Epiphany obturation system consisted of a core material (Resilon), a dual-curing resin-based sealer (Epiphany), and a self-etching primer (3, 6). The second generation, new Epiphany self-etch (SE) soft resin endodontic obturation system, has been marketed consisting of two components: Epiphany self-adhesive (Epiphany SE; Parkell, Farmington, NY) sealer and Resilon. Acidic resin monomers that are originally found in SE primers have been incorporated into the self-adhesive resin-based sealers (eg, Epiphany SE, MetaSeal [Parkell], and RealSeal SE [SybronEndo, Orange, CA]) to make them advantageous. These types of sealers reduce the application time as well as errors during bonding steps (7, 8). Adhesive root-filling materials have been a matter of extensive research in the past few years (9). Although these materials may be advantageous in theory, some requirements need to be fulfilled (10). Several studies have compared the bond strength of gutta-percha and Resilon used in combination with different sealers to the root canal dentin (11–13). However, detailed information on adhesive properties of self-adhesive root canal sealers is limited because they are relatively new (8). The penetration of sealer cements into dentinal tubules is considered to be potentially beneficial. Sealer penetration increases the interface between material and dentinal walls; this may improve the mechanical retention of the material by interlocking of the sealer plug inside the tubules (14); this potentially reduces leakage (15).
From the *Department of Endodontics/Dental Research Center, School of Dentistry, Tehran University of Medical Sciences and Iranian Center for Endodontic Research, Tehran, Iran; †Department of Endodontics, University of Southern California, School of Dentistry, Los Angeles, California; ‡Oral and Dental Diseases Research Center, School of Dentistry, Kerman University of Medical Sciences, Kerman, Iran; §Department of Dental Material, Dental School, Azad University/Kamal Asgar Research Center (KARC), Tehran, Iran; kResearch Center for Pharmaceutical Nanotechnology and Department of Endodontics, Dental Faculty, Tabriz University (Medical Sciences), Tabriz, Iran; and ¶Private Practice, Shiraz, Iran. Supported by Tehran University of Medical Sciences and Health Services grant No. 12870. Address requests for reprints to Dr Mohammad Sabeti, PO Box 14374, Irvine, CA 92623. E-mail address: [email protected] 0099-2399/$ - see front matter Copyright ª 2011 American Association of Endodontists. doi:10.1016/j.joen.2011.05.002
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Basic Research—Technology Furthermore, the sealer’s antibacterial activity can be effective for killing and entombing bacteria that remain inside the dentinal tubules (16). The ability of sealer to penetrate dentinal tubules consistently and effectively is one of many factors influencing the choice of material for root canal filling (15). The penetration depth of epoxy resin-based sealers has been evaluated by some studies (15, 17). Furthermore, Patel et al (18) and Gharib et al (19) examined the penetration depth of the nonadhesive type of Epiphany and RealSeal into the dentinal tubules in extracted teeth filled with Resilon in combination with these resin-based sealers. To the best of our knowledge, there is no information about the penetration depth of the self-adhesive type of methacrylate resin-based sealers such as Epiphany SE into dentinal tubules. Therefore, this study was designed to compare the tubular penetration depth of AH Plus (Dentsply, DeTrey, Konstanz, Germany), Epiphany, and Epiphany SE.
Materials and Methods Thirty-six, extracted, human single-rooted premolars with straight canals were selected and stored in 0.5% chloramine-T before use. The crowns were removed to a standardized root length of 14 mm. A size 10 K-type file was inserted into the root canal until it could be seen through the apical foramen. The working length was established by reducing this length by 1 mm. The root canals were prepared using Mtwo Ni-Ti rotary instruments (VDW, Munich, Germany) according to the manufacturer’s instructions in the following sequence: (1) 10/.04, (2) 15/.05, (3) 20/ .06, (4) 25/.06, (5) 30/.05, and (6) 35/.04. NaOCl (5.25%) was used as the irrigant between files for a total of 5 mL. After completion of preparation, the root canals were irrigated with 5 mL of 17% EDTA for 1 minute and then finally rinsed with 10 mL of saline solution. All canals were dried with paper points; next, they were randomly divided into 3 groups of 12 teeth each as follows.
Group 1: Gutta-Percha/AH Plus In this group, the root canals were obturated with a size 35/0.02 gutta-percha (Gapadent Co, Ltd, Tianjin, China) master cone, which was coated with AH Plus sealer using cold lateral compaction technique. Accessory cones (size 20/0.02) coated with sealer were inserted into the canal until the entire root canal was filled. The excess guttapercha was removed with a heated instrument and then compacted vertically using a plugger. Group 2: Resilon/Epiphany Epiphany self-etching primer was introduced into the canal with a soaked paper point. After removing the excess primer with a dry paper point, a Resilon master cone (size 35/.02) was lightly coated with Epiphany sealer and placed into the canal to the working length. Lateral
compaction using accessory Resilon cones size 20/.02 was performed until the entire root canal was filled. The excess Resilon cones were removed with a heated instrument and then compacted vertically using a plugger. The coronal surface of the obturation was light-cured for 40 seconds to create an immediate coronal seal according to the manufacturer’s instructions.
Group 3: Resilon/Epiphany SE After mixing the Epiphany SE sealer on a mixing pad, Resilon master cone (size 35/.02) was lightly coated with Epiphany sealer and placed into the canal to the working length. The root canals were then obturated using a cold lateral compaction technique in the same manner as group 2. The quality of obturation was then confirmed radiographically. The root canal entrances were sealed with a temporary filling material (Coltosol; Coltene Whaledent, Mahwah, NJ). The specimens were stored at 37 C and 100% humidity for 7 days. After that, two longitudinal grooves were prepared on the buccal and lingual surfaces of each root using a diamond disc without penetration into the canal. The roots were then split into two halves with a chisel, producing two specimens per tooth (24 specimens per group). Because total sealer tags were impossible to count, four notches were made in each half using a scalpel: 4, 6, 8, and 10 mm apical to the most coronal level of the each root (18). Before scanning electron microscopic examination, the specimens were placed in 2% glutaraldehyde for 24 hours and then rinsed three times with sodium cacodylate-buffered solution (0.1 mol/L, pH = 7.2). After incubation in osmium tetroxide for 1 hour, the samples were dried for 24 hours. The specimens were then mounted on metallic stubs, gold sputtered, and examined with a scanning electron microscope (Leo 440i; Oxford Microscopy, Oxford, UK) that was equipped with a secondary electron detector (Fig. 1A). Digital images were recorded using a Microsoft picture manager (Redmond, WA) and processed with ImageJ program (Rasband WS, ImageJ; US National Institute of Health, Bethesda, MD) (Fig. 1B). Observations were performed at the dentin-sealer interface of the areas immediately apical and coronal to the notches and only on one side of the canal. The maximum penetration depth of the sealer into the dentinal tubules was measured in micrometers at the mentioned areas. Therefore, eight measurements were performed in each root half. These values were averaged to obtain a single observation for each root half. The data were analyzed by one-way analysis of variance and a post hoc Tukey test at a significance level of P < .05.
Results The mean ( standard deviation) values for the average depths of dentinal tubule sealer penetration in the middle third of the roots are
Figure 1. (A) An SEM micrograph at a higher magnification (3,000). (B) The image processed with ImageJ software. Arrows show sealer tags. JOE — Volume 37, Number 9, September 2011
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Basic Research—Technology TABLE 1. Penetration Depth of the Three Sealers (mm) Group
Sample size
Mean penetration ± standard deviation
1: Gutta-percha/AH Plus 2: Resilon/Epiphany 3: Resilon/Epiphany SE
24 24 24
22.07 6.92A 31.56 6.80B 21.50 9.25A
Values with the same superscript letter are not statistically different at P = .05.
shown in Table 1. The difference between these values was statistically significant (P = .028). The post hoc Tukey test revealed that the penetration depth of Epiphany was significantly higher than that of Epiphany SE and AH Plus (P < .05). However, there was no significant difference between the penetration depth of Epiphany SE and AH Plus (P > .05).
Discussion Removal of the smear layer is considered to be essential for root canal sealers to penetrate into dentinal tubules irrespective of the sealer used (20). Alternating the use of 5.25% NaOCl and 17% EDTA had been previously recommended for the effective removal of both the organic and inorganic components of the smear layer (21). The relevant literature shows a wide variety of irrigation times in removing the smear layer. The effectiveness of a 1-minute irrigation with 17% EDTA on smear layer removal has been shown (22). Therefore, in this study, EDTA was used for a short time (1 minute) to minimize destructive effects on dentin (23). Scanning electron microscopy has been used in several studies to evaluate the penetration of root canal sealers into the dentinal tubules (15, 17, 24–26). This technique provides a number of advantages. Scanning electron microscopic micrographs allow for observation of the dentinal tubules and accurate measurement of penetration depth of the sealers into dentinal tubules at a high magnification. In addition, it allows for the observation of sealer within dentinal tubules at distant sites from the root canal wall where the density of the tubules is lower. However, the inability to obtain a detailed overall view at low magnification is the main disadvantage of this technique. Furthermore, there is a potential for producing artifacts during the preparation of the specimens for SEM (15). Regional variation in the depth of sealer penetration has been shown by several authors (27, 28). The deepest penetration of sealer has been shown in the middle third of the root canal (24). Similar to Mamootil and Messer’s study (15), the sections evaluated in this study were representative of dentin from the middle thirds of the roots. Because AH Plus has been used in comparative studies of root canal sealers (29, 30), it was tested for comparison in this study. This study showed that the average penetration depth of Epiphany in the middle third of the root was significantly higher than that of the other sealers. This finding is partly in accordance with the results of the only study that compared the penetration depth of RealSeal (Epiphany) and Tubliseal (Kerr, Scafati, Italy), a sealer cement based on zinc oxide eugenol, and showed a significantly higher penetration depth for RealSeal (18). However, Patel et al (18) reported the mean penetration depth of RealSeal to be 914.88 mm in the middle third of the roots, which is different from the mean penetration value for Epiphany in this study (31.56 mm). The possible reasons for these conflicting results might be as follows: the methodology used to assess the sealer penetration depth could result in different findings. In the present study, the penetration depth was assessed using SEM, but confocal laser scanning microscopy (CLSM) was used in the study by Patel et al (18). Also, the controversial findings might be attributed to the mode of teeth sectioning, which was longitudinal in both studies. The whole dentin 1318
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surrounding the canal cannot be fully observed in longitudinal sections (14). Therefore, different values for sealer penetration could be obtained in various studies because there is potential to miss areas of deep penetration dependent on the location of the longitudinal section (15). Patel et al (18) measured the maximum penetration depth of the RealSeal on either side of the canal for each root half, but one side of the canals was evaluated in the present study. The result of this study for the average tubular penetration depth of Epiphany (31.56 mm) is not in accordance with the finding of Gharib et al (19). They assessed the horizontal root sections using CLSM and reported an average penetration depth of 538.1 mm for Epiphany in the middle third. These different results might be attributed to different modes of root sectioning (longitudinal vs horizontal) and different assessment methods (SEM vs CLSM). Different values for Epiphany penetration reported by Patel et al (18) and Gharib et al (19), which used CLSM, might be partly explained by the mode of root sectioning, which was longitudinal and horizontal, respectively. In addition, to facilitate fluorescence under confocal laser microscopy, the test subject is labeled with a fluorescent dye (19). In assessing the penetration depth of Epiphany, depending on the component labeled (primer, sealer, or both of them), the results might be affected. Patel et al (18) mixed RealSeal primer with the fluorescent dye, but Gharib et al (19) labeled the Epiphany sealer. This study showed that the average penetration depth of AH Plus into the dentinal tubules was 22.07 mm. Kokkas et al (17), in a study of longitudinal root sections using SEM, reported a mean maximum penetration depth of 54.6 mm for AH Plus, and their finding is quite consistent with our results. On the other hand, Mamootil and Messer (15), who evaluated the horizontal root sections using SEM, reported that the mean maximum penetration depth of AH26 (De Trey, Dentsply, Konstanz, Germany) was 1337 mm in the middle third. The penetration of root canal sealers into dentinal tubules might be influenced by variations in the physical and chemical properties of the sealers (31). Kokkas et al (17) revealed that AH Plus and Apexit (Vivadent; Ivoclaar, Schaan, Liechtenstein) sealers appeared to have a significantly greater maximum penetration depth in comparison with Roth 811 (Roth International, Chicago, IL). In addition, Mamootil and Messer (15) showed that there was a significant difference between the penetration depth of each of three different sealer cements: epoxy resin (AH26), zinc oxide eugenol (Pulp Canal Sealer EWT; Kerr, Sybron Dental Specialties, Romulus, MI), and methacrylate resin (EndoREZ; Ultradent Products, South Jordan, UT). The results of the present study revealed that the average penetration depth of the non-SE type of methacrylate resin–based sealer (Epiphany) was significantly higher than that of Epiphany SE. This difference might be attributed to the different composition of Epiphany and Epiphany SE. Acidic resin monomers incorporated into the self-adhesive resin-based sealers might influence the behavior of these sealers. In the present study, however, there was no significant difference between the penetration depth of Epiphany SE and AH Plus despite their different chemical composition. In conclusion, the average penetration depth of Epiphany into the dentinal tubules in the middle third of the roots filled with Resilon was significantly higher than that of Epiphany SE and AH Plus in roots filled with Resilon and gutta-percha, respectively. Although the penetration of root canal sealers into the dentinal tubules might be important from a clinical aspect, future studies should be considered to evaluate new root canal sealers in clinical situations.
Acknowledgments The authors deny any conflicts of interest related to this study. JOE — Volume 37, Number 9, September 2011
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