Get 20M+ Full-Text Papers For Less Than $1.50/day. Start a 14-Day Trial for You or Your Team.

Learn More →

The effect of endodontic chemicals on the retention of fiber posts luted using a self-adhesive cement

The effect of endodontic chemicals on the retention of fiber posts luted using a self-adhesive... patriciajardim.ufpel@gmail.com Department of Operative The aim of this study was to assess the effect of endodontic chemical substances on Dentistry, School of Dentistry, the retention of fiber posts luted using a self-adhesive cement. Single-canal human Federal University of Pelotas, Pelotas, RS, Brazil roots of 75 teeth were divided into 5 groups (n = 15). Root canals were instrumented Full list of author information is with one of the following substances: 0.9% NaCl (control); 5.25% sodium hypochlorite; available at the end of the article 5.25% Sodium hypochlorite + 17% EDTA; 2% chlorhexidine gel; 2% chlorhexidine gel + 17% EDTA. After chemo-mechanical preparation, fiber post cementation was performed with self-adhesive resin cement (RelyX Unicem, 3 M/ESPE). One-way ANOVA was performed followed by a multiple comparison Tukey post hoc test (α =5%). The use of 2% chlorhexidine gel resulted bond strength statistically similar to the control group (p = 0.418), which was higher than the other groups. A final irrigation with 17% EDTA significantly reduced bond strength (p < 0.001). The use of 5.25% sodium hypochlorite negatively affected the bond strength, either with or without a final irrigation with 17% EDTA (p < 0.001). Our results suggest that 2% chlorhexidine gel used during endodontic chemo-mechanical preparation, without a final irrigation with 17% EDTA, promotes a more favorable condition to the retention of fiber posts luted using a self-adhesive cement than 5.25% sodium hypochlorite. Keywords: Chlorhexidine; EDTA; Fiber glass posts; Push out; Resin cement Background Glass-fiber posts are an important clinical option to provide retention for coronal den- tal restorations, as they have the elastic modulus is similar to that of dentin, and are cemented by an adhesive technique [1]. The debonding at the dentin/cement interface has been considered the major cause of fiber post restorations failure [2,3]. Thus, a propitious environment for both root dentin hybridization and stability of the bond strength must be intended. One of the factors affecting the bond strength of fiber posts is the chemical sub- stance used for biomechanical preparation of root canals [4]. The most commonly used substance in endodontic treatment is sodium hypochlorite (NaOCl), in various concentrations, due to its known antibacterial activity and its capability of dissolving organic tissues [5-7]. Currently, however, 2% chlorhexidine (CHX) gel has been widely used as an alternative auxiliary substance to root canal treatment due to properties © 2014 Jardim et al.; licensee Springer. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. Jardim et al. Applied Adhesion Science Page 2 of 6 2014, 2:20 http://www.appliedadhesionscience.com/content/2/1/20 such as broad antimicrobial spectrum, substantivity, and low cytotoxicity [8,9]. More- over, endodontic protocols indicate the application of 17% Ethylene diamine tetracetic acid (EDTA) as a final irrigating solution, in order to promote an appropriate cleaning of the root canal walls, consequently, improving the penetration of chemical substances and promoting a better contact between the dentin walls and filling material [10,11]. It has been shown that 2% CHX gel does not interfere with the collagen present in the organic matrix of root dentin, while 5.25% NaOCl, whether associated or not with 17% EDTA, causes birefringence alterations of dentin collagen [12]. The preservation of the collagen fibrils is essential for the adhesion of resin materials to dentin, as they promote micromechanical retention and participate in the process of chemical union between the hydroxyapatite present in collagen fibers and some self-etching adhesive materials [13]. The pre-treatment of dentin surface with CHX has been shown to reduce the bond strength of self-adhesive resin cements to dentin [14]. On the other hand, a final rinse with CHX did not affect the immediate push-out bond strength in post bond cementa- tion with self-adhesive resin cements [15]. However, the performance of chemical sub- stances used for biomechanical preparation of the root canals on the bond strength of self-etching adhesive resin cements remains unknown. Hence, the aim of this study was to evaluate the effect of the substances used as endodontic auxiliary chemical sub- stances, 5.25% NaOCl and 2% CHX gel and their association with 17% EDTA on the retention of fiber posts luted using a self-adhesive cement. The study tested the null hypothesis that endodontic substances do not affect the bond strength of fiber posts cemented with self-adhesive resin cement. Methods This study was approved by the Local Research and Ethics Committee of the Federal Univer- sity of Pelotas (150/2010). Single rooted caries-free human teeth were obtained and exam- ined. Roots with open apices and resorptive defects were excluded and seventy-five teeth were randomly divided into five groups (n = 15), according to the endodontic substance used. Teeth were mechanically cleaned with a curette to remove soft tissue remnants from the root surfaces. The teeth were decoronated at the cementoenamel junction (CEJ) with a double-sided diamond disk (Isomet, Buehler, Lake Bluff, IL, USA) in low-speed rotary instrument under constant water-cooling, in order to leave 15 mm of root length. A size 10 K-file (Dentsply Maillefer, Ballaigues, Switzerland) was used to create an apical stop with a step-back preparation. Working length was determined by placing the instru- ment into the canal until visible at the apical foramen and subtracting 1 mm from this length. The cervical portion of the root was prepared with Gattes-Gliden drills up to 11 mm. Next, the root canals were instrumented with K-flex endodontic files (Maillefer/ Dentsply) in sequence up to K = 50 associated to the previously determined substance for each group, as follows: 0.9% NaCl (control), 2% CHX gel, 2% CHX gel with final irrigation with 17% EDTA, 5.25% NaOCl and 5.25% NaOCl with final irrigation with 17% EDTA. The working time was standardized for each file (1 min), as well as the volume of the sub- stance used (30 mL of 0.9% NaCl, 5.25% NaOCl and 17% EDTA; 3 mL of 2% CHX gel followed by 30 mL of 0.9% NaCl). When the endodontic preparation was complete, the root canals were prepared for fiber post cementation (#0.5, White Post DC, FGM, Brazil) using the drill of the post Jardim et al. Applied Adhesion Science Page 3 of 6 2014, 2:20 http://www.appliedadhesionscience.com/content/2/1/20 system. The canals were thoroughly washed with saline solution and kept moist until use. Absorbent paper points were used to remove the excess of saline solution from the canals. Finally, the fiber post was previously prepared by cleaning with 70% ethanol, air-dried and silanized for 1 min and gently air dried for 5 s (Silano, Angelus, Brazil). The self-adhesive cement was prepared according to manufacturer’s instructions and the resin cement was inserted into the root canal (RelyX Unicem, 3 M ESPE, St Paul, MN, USA). The fiber post was immediately placed to seat, excess of the cement was re- moved with a microbrush and the luting composite was light-cured for 60 s (Radii-Cal, SDI, Australia). Specimens were then stored at 100% humidity and 37°C for 24 h to allow complete polymerization. The specimens were fixed on acrylic plates and then sectioned trans- versally into 1.5 mm slices containing cross sections of the fiber postsunder water- cooling with a precision machine (Buehler Isomet, USA). The cervical and apical diameter of the canal and the thickness of all of the slices were measured with a digital caliper (Mitutoyo Digimatic Caliper, France). Push-out strength test Each section was marked on its apical side and positioned on a base, with a central hole, in a universal testing machine (DL2000, EMIC, São José dos Pinhais, PR, Brazil). The push-out test was performed by applying a compressive load to the apical side of each slice by using a 0.7-mm-diameter cylindrical plunger attached to theupper portion of the testing machine. A crosshead speed of 0.5 mm/min was applied until bond fail- ure occurred. The load upon failure was recorded in Newton (N). The force required for dislocation of the post (bond strength) was calculated as follows: F = R/A, where F = force of displacement of the post (N), and A = bond area (mm2). Calculation of the bond area: A = π.g. (R1 + R2); where π = 3.14; g = taper of the root [g = (h2 + (R2-R1) 2) 1 / 2]; R1 represents root opening in the apex and R2 represents the root opening in the cervical. R1 and R2 were measured in Image-J (Wayne Rasband, National Institutes of Health, Bethesda, MA, USA). Thickness of the slices (h) was measured with a digital caliper. The bond strength values of the tooth slices of each group were averaged for statistical analysis. Statistical analysis The data were analyzed using a statistical software package (R, Version 0.98.490 – © 2009–2013 RStudio, Inc. USA). For comparison among chemical substances, one-way ANOVA was performed followed by a multiple comparison Tukey post hoc test. Statis- tical significance was considered as α = 5%. Results and discussion Table 1 shows the comparison among the five groups, which resulted in statistically significant differences (p < 0.001). The use of NaOCl as a chemical substance re- sulted in the lowest bond strength (p < 0.001). The same trend occurred with both groups with EDTA (either with NaOCl or CHX; p < 0.001). The group where CHX was used alone resulted in the same bond strength values as the control group (NaCl; p = 0.455). The use of 2% CHX gel did not affect the bond strength of the cement tested. However, the use of CHX gel with a final irrigation with 17% EDTA Jardim et al. Applied Adhesion Science Page 4 of 6 2014, 2:20 http://www.appliedadhesionscience.com/content/2/1/20 Table 1 Mean ± standard deviations push-out bond strength of glass fiber posts (in MPa) Substance Push-out Control 14.0 ± 8.1 A NaOCl 5.3 ± 3.3 B Chlorhexidine 9.6 ± 4.6 A EDTA + NaOCl 8.7 ± 4.8 B EDTA + Chlorhexidine 5.4 ± 2.7 B Upper case letter represents statistically significant differences among irrigants (p < 0.05). significantly reduced the bond strength. The use of 5.25% NaOCl negatively affec- ted the bond strength of the cement tested, either with or without a final irrigation with 17% EDTA. The use of 5.25% NaOCl for chemo-mechanical preparation of root canals, either with or without a final irrigation with 17% EDTA, presented statistically significant de- crease on the bond strength of fiber post cemented with self-adhesive resin cement. The efficiency of adhesive systems is directly related to the dentin quality and collagen integrity. The fact that NaOCl is an efficient organic solvent that causes dissolution of dentin collagen fibrils [12,16] might explain its negative influence on the bond strength of the self-adhesive resin cement shown in this study, since collagen plays an important role in the formation of the hybrid layer. CHX gel has been widely used in endodontics and one of its most important features is not affecting the dentin collagen matrix [12]. The results of the present study indi- cate that 2% CHX gel does not interfere with the bond strength of self-adhesive resin cements. On the other hand,it has been shown that when CHX solution was used as cavity cleanser, the residual solution and moisture contamination might be able to interfere with the bonding of RelyX Unicem to dentin, resulting in lower bond strengths [14]. Nevertheless, it is important to highlight that in the present study, CHX was used as a gel auxiliary to the root canal biochemical preparation and not as cavity cleanser solution. The final application of 17% EDTA after chemo-mechanical preparation with 2% CHX gel significantly reduced the bond strength. The application of EDTA reduces the Ca ions available on the surface of the canal walls; therefore, the potential chemical bonding that would be expected with self-adhesive resin cements is compromised af- fecting the final bond strength. The probable explanation is that the smear layer re- moval, promoted by the application of EDTA, facilitates resinous monomer penetration into the dentinal tubules [17]. Self-adhesive resin cements present a series of advantages on the bond of fiber posts, e.g. reduced clinical chair time, as they do not require any pre-treatment of the dental substrate, and elimination of the following steps: priming and air-drying for solvent evaporation [18-20]. However, the results of the present study showed that 5.25% NaOCl, either with or without 17% EDTA, affected the bond strength between self- adhesive resin cement and root canal dentin. Eventually, 2% CHX gel promoted a more favorable condition to the cementation of fiber posts with self-adhesive resin cement than 5.25% NaOCl, and should be preferred in the root canal biomechanical prepa- ration, without a final application of 17% EDTA, when a fiber post is planned to be cemented with self-adhesive resin cement. Jardim et al. Applied Adhesion Science Page 5 of 6 2014, 2:20 http://www.appliedadhesionscience.com/content/2/1/20 Conclusion The use of 2% chlorhexidine gel resulted on retention of fiber posts luted using a self- adhesive cement statistically similar to the control group (p = 0.418), which was higher than the other groups. A final irrigation with 17% EDTA significantly reduced on the retention of fiber posts luted using a self-adhesive cement. The use of 5.25% NaOCl negatively affected the bond strength, either with or without a final irrigation with 17% EDTA. Competing interests The authors declare that they have no competing interests. Authors’ contributions RCJ and TPC contributed to study design, data interpretation, manuscript drafting and critical revision; CFB and ACAF participated in the specimen preparation, laboratory analyses, data collection and manuscript drafting; PSJ participated in the study design, supervision of laboratory research, data interpretation, manuscript drafting and critical revision. All authors read and approved the final manuscript. Author details Department of Operative Dentistry, School of Dentistry, Federal University of Pelotas, Pelotas, RS, Brazil. Department of Semiology and Clinics, School of Dentistry, Federal University of Pelotas, Pelotas, RS, Brazil. Received: 13 November 2013 Accepted: 30 January 2014 Published: 04 Aug 2014 References 1. de Moraes AP, Cenci MS, Moraes RR, Pereira-Cenci T (2013) Current concepts on the use and adhesive bonding of glass-fiber posts in dentistry: a review. Appl Adhes Sci 1:4. doi:10.1186/2196-4351-1-4 2. Iglesia-Puig MA, Arellano-Cabornero A (2004) Fiber-reinforced post and core adapted to a previous metal ceramic crown. J Prosthet Dent 91:191–194. doi:10.1016/j.prosdent.2003.11.004 3. Grandini S, Goracci C, Monticelli F, Borracchini A, Ferrari M (2005) SEM evaluation of the cement layer thickness after luting two different posts. J Adhes Dent 7:235–240. doi:10.3290/j.jad.a10486 4. Farina AP, Cecchin D, Barbizam JV, Carlini-Júnior B (2011) Influence of endodontic irrigants on bond strength of a self-etching adhesive. Aust Endod J 37:26–30. doi:10.1111/j.1747-4477.2010.00249.x 5. Gomes BP, Ferraz CC, Vianna ME, Berber VB, Teixeira FB, Souza-Filho FJ (2001) In vitro antimicrobial activity of several concentrations of sodium hypochlorite and chlorhexidine gluconate in the elimination of Enterococcus faecalis. Int Endod J 34:424–428 6. Stojicic S, Zivkovic S, Qian W, Zhang H, Haapasalo M (2010) Tissue dissolution by sodium hypochlorite: effect of concentration, temperature, agitation, and surfactant. J Endod 36:1558–1562. doi:10.1016/ j.joen.2010.06.021 7. Shenoy A, Mandava P, Bolla N, Raj S, Kurien J, Prathap MS (2013) Antibacterial efficacy of sodium hypochlorite with a novel sonic agitation device. Indian J Dent Res 24:537–541. doi:10.4103/0970-9290.123361 8. Dametto FR, Ferraz CC, Gomes BP, Zaia AA, Teixeira FB, de Souza-Filho FJ (2005) In vitro assessment of the immediate and prolonged antimicrobial action of chlorhexidine gel as an endodontic irrigant against Enterococcus faecalis. Oral Surg Oral Med Oral Pathol Oral Radiol Endod 99:768–772. doi:10.1016/ j.tripleo.2004.08.026 9. Gomes BP, Vianna ME, Zaia AA, Almeida JF, Souza-Filho FJ, Ferraz CC (2013) Chlorhexidine in endodontics. Braz Dent J 24:89–102. doi:10.1590/0103-6440201302188 10. Johal S, Baumgartner JC, Marshall JG (2007) Comparison of the antimicrobial efficacy of 1.3% NaOCl/BioPure MTAD to 5.25% NaOCl/15% EDTA for root canal irrigation. J Endod 33:48–51. doi:10.1016/j.joen.2006.08.007 11. Arslan H, Yılmaz CB, Karatas E, Barutcigil C, Topcuoglu HS, Yeter KY (2013) Efficacy of different treatments of root canal walls on the pull-out bond strength of the fiber posts. Lasers Med Sci, doi:10.1007/ s10103-013-1457-4 12. Moreira DM, Almeida JF, Ferraz CC, Gomes BP, Line SR, Zaia AA (2009) Structural analysis of bovine root dentin after use of different endodontics auxiliary chemical substances. J Endod 35:1023–1027. doi:10.1016/ j.joen.2009.04.002 13. Moodley D, Grobler SR (2002) Dentine bonding agents–a review of adhesion to dentine. J South Afr Dent Assoc 57:234–238 14. Hiraishi N, Yiu CK, King NM, Tay FR (2010) Effect of chlorhexidine incorporation into a self-etching primer on dentine bond strength of a luting cement. J Dent 38:496–502. doi:10.1016/j.jdent.2010.03.005 15. Gerth HU, Dammaschke T, Zuchner H, Schäfer E (2006) Chemical analysis and bonding reaction of RelyX Unicem and Bifix composites—a comparative study. Dent Mater 22:934–941. doi:10.1016/j.dental.2005.10.004 16. Ishizuka T, Kataoka H, Yoshioka T, Suda H, Iwasak N, Takahashi H, Nishimura F (2001) Effect of NaOCl treatment on bonding to root canal dentin using a new evaluation method. Dent Mater J 20:24–33 17. Miyasak K, Nakabayashi N (1999) Combination of EDTA conditioner and Phenyl-HEMA self-etching primer for bonding to dentin. Dent Mater 15:153–157. doi:10.1016/S0300-5712(99)00025-1 Jardim et al. Applied Adhesion Science Page 6 of 6 2014, 2:20 http://www.appliedadhesionscience.com/content/2/1/20 18. Faria-e-Silva AL, Pedrosa-Filho CF, Menezes MS, Silveira DM, Martins LR (2009) Effect of relining on fiber post retention to root canal. J Appl Oral Sci 17:600–604. doi:10.1590/S1678-77572009000600012 19. Kececi AD, Ureyen KB, Adanir N (2008) Micro push-out bond strengths of four fiber-reinforced composite post systems and 2 luting materials. Oral Surg Oral Med Oral Pathol Oral Radiol Endod 105:121–128. doi:10.1016/ j.tripleo.2007.07.011 20. Radovic I, Monticelli F, Goracci C, Vulicevic ZR, Ferrari M (2008) Self-adhesive resin cements: a literature review. J Adhes Dent 10:251–258. doi:10.3290/j.jad.a13735 10.1186/2196-4351-2-20 Cite this article as: Jardim et al.: The effect of endodontic chemicals on the retention of fiber posts luted using a self-adhesive cement. Applied Adhesion Science 2014, 2:20 Submit your manuscript to a journal and benefi t from: 7 Convenient online submission 7 Rigorous peer review 7 Immediate publication on acceptance 7 Open access: articles freely available online 7 High visibility within the fi eld 7 Retaining the copyright to your article Submit your next manuscript at 7 springeropen.com http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png Applied Adhesion Science Springer Journals

The effect of endodontic chemicals on the retention of fiber posts luted using a self-adhesive cement

Loading next page...
 
/lp/springer-journals/the-effect-of-endodontic-chemicals-on-the-retention-of-fiber-posts-aKvXdoarI4
Publisher
Springer Journals
Copyright
Copyright © 2014 by Jardim et al.; licensee Springer.
Subject
Material Science; Surfaces and Interfaces, Thin Films; Mechanical Engineering; Biomaterials
eISSN
2196-4351
DOI
10.1186/2196-4351-2-20
Publisher site
See Article on Publisher Site

Abstract

patriciajardim.ufpel@gmail.com Department of Operative The aim of this study was to assess the effect of endodontic chemical substances on Dentistry, School of Dentistry, the retention of fiber posts luted using a self-adhesive cement. Single-canal human Federal University of Pelotas, Pelotas, RS, Brazil roots of 75 teeth were divided into 5 groups (n = 15). Root canals were instrumented Full list of author information is with one of the following substances: 0.9% NaCl (control); 5.25% sodium hypochlorite; available at the end of the article 5.25% Sodium hypochlorite + 17% EDTA; 2% chlorhexidine gel; 2% chlorhexidine gel + 17% EDTA. After chemo-mechanical preparation, fiber post cementation was performed with self-adhesive resin cement (RelyX Unicem, 3 M/ESPE). One-way ANOVA was performed followed by a multiple comparison Tukey post hoc test (α =5%). The use of 2% chlorhexidine gel resulted bond strength statistically similar to the control group (p = 0.418), which was higher than the other groups. A final irrigation with 17% EDTA significantly reduced bond strength (p < 0.001). The use of 5.25% sodium hypochlorite negatively affected the bond strength, either with or without a final irrigation with 17% EDTA (p < 0.001). Our results suggest that 2% chlorhexidine gel used during endodontic chemo-mechanical preparation, without a final irrigation with 17% EDTA, promotes a more favorable condition to the retention of fiber posts luted using a self-adhesive cement than 5.25% sodium hypochlorite. Keywords: Chlorhexidine; EDTA; Fiber glass posts; Push out; Resin cement Background Glass-fiber posts are an important clinical option to provide retention for coronal den- tal restorations, as they have the elastic modulus is similar to that of dentin, and are cemented by an adhesive technique [1]. The debonding at the dentin/cement interface has been considered the major cause of fiber post restorations failure [2,3]. Thus, a propitious environment for both root dentin hybridization and stability of the bond strength must be intended. One of the factors affecting the bond strength of fiber posts is the chemical sub- stance used for biomechanical preparation of root canals [4]. The most commonly used substance in endodontic treatment is sodium hypochlorite (NaOCl), in various concentrations, due to its known antibacterial activity and its capability of dissolving organic tissues [5-7]. Currently, however, 2% chlorhexidine (CHX) gel has been widely used as an alternative auxiliary substance to root canal treatment due to properties © 2014 Jardim et al.; licensee Springer. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. Jardim et al. Applied Adhesion Science Page 2 of 6 2014, 2:20 http://www.appliedadhesionscience.com/content/2/1/20 such as broad antimicrobial spectrum, substantivity, and low cytotoxicity [8,9]. More- over, endodontic protocols indicate the application of 17% Ethylene diamine tetracetic acid (EDTA) as a final irrigating solution, in order to promote an appropriate cleaning of the root canal walls, consequently, improving the penetration of chemical substances and promoting a better contact between the dentin walls and filling material [10,11]. It has been shown that 2% CHX gel does not interfere with the collagen present in the organic matrix of root dentin, while 5.25% NaOCl, whether associated or not with 17% EDTA, causes birefringence alterations of dentin collagen [12]. The preservation of the collagen fibrils is essential for the adhesion of resin materials to dentin, as they promote micromechanical retention and participate in the process of chemical union between the hydroxyapatite present in collagen fibers and some self-etching adhesive materials [13]. The pre-treatment of dentin surface with CHX has been shown to reduce the bond strength of self-adhesive resin cements to dentin [14]. On the other hand, a final rinse with CHX did not affect the immediate push-out bond strength in post bond cementa- tion with self-adhesive resin cements [15]. However, the performance of chemical sub- stances used for biomechanical preparation of the root canals on the bond strength of self-etching adhesive resin cements remains unknown. Hence, the aim of this study was to evaluate the effect of the substances used as endodontic auxiliary chemical sub- stances, 5.25% NaOCl and 2% CHX gel and their association with 17% EDTA on the retention of fiber posts luted using a self-adhesive cement. The study tested the null hypothesis that endodontic substances do not affect the bond strength of fiber posts cemented with self-adhesive resin cement. Methods This study was approved by the Local Research and Ethics Committee of the Federal Univer- sity of Pelotas (150/2010). Single rooted caries-free human teeth were obtained and exam- ined. Roots with open apices and resorptive defects were excluded and seventy-five teeth were randomly divided into five groups (n = 15), according to the endodontic substance used. Teeth were mechanically cleaned with a curette to remove soft tissue remnants from the root surfaces. The teeth were decoronated at the cementoenamel junction (CEJ) with a double-sided diamond disk (Isomet, Buehler, Lake Bluff, IL, USA) in low-speed rotary instrument under constant water-cooling, in order to leave 15 mm of root length. A size 10 K-file (Dentsply Maillefer, Ballaigues, Switzerland) was used to create an apical stop with a step-back preparation. Working length was determined by placing the instru- ment into the canal until visible at the apical foramen and subtracting 1 mm from this length. The cervical portion of the root was prepared with Gattes-Gliden drills up to 11 mm. Next, the root canals were instrumented with K-flex endodontic files (Maillefer/ Dentsply) in sequence up to K = 50 associated to the previously determined substance for each group, as follows: 0.9% NaCl (control), 2% CHX gel, 2% CHX gel with final irrigation with 17% EDTA, 5.25% NaOCl and 5.25% NaOCl with final irrigation with 17% EDTA. The working time was standardized for each file (1 min), as well as the volume of the sub- stance used (30 mL of 0.9% NaCl, 5.25% NaOCl and 17% EDTA; 3 mL of 2% CHX gel followed by 30 mL of 0.9% NaCl). When the endodontic preparation was complete, the root canals were prepared for fiber post cementation (#0.5, White Post DC, FGM, Brazil) using the drill of the post Jardim et al. Applied Adhesion Science Page 3 of 6 2014, 2:20 http://www.appliedadhesionscience.com/content/2/1/20 system. The canals were thoroughly washed with saline solution and kept moist until use. Absorbent paper points were used to remove the excess of saline solution from the canals. Finally, the fiber post was previously prepared by cleaning with 70% ethanol, air-dried and silanized for 1 min and gently air dried for 5 s (Silano, Angelus, Brazil). The self-adhesive cement was prepared according to manufacturer’s instructions and the resin cement was inserted into the root canal (RelyX Unicem, 3 M ESPE, St Paul, MN, USA). The fiber post was immediately placed to seat, excess of the cement was re- moved with a microbrush and the luting composite was light-cured for 60 s (Radii-Cal, SDI, Australia). Specimens were then stored at 100% humidity and 37°C for 24 h to allow complete polymerization. The specimens were fixed on acrylic plates and then sectioned trans- versally into 1.5 mm slices containing cross sections of the fiber postsunder water- cooling with a precision machine (Buehler Isomet, USA). The cervical and apical diameter of the canal and the thickness of all of the slices were measured with a digital caliper (Mitutoyo Digimatic Caliper, France). Push-out strength test Each section was marked on its apical side and positioned on a base, with a central hole, in a universal testing machine (DL2000, EMIC, São José dos Pinhais, PR, Brazil). The push-out test was performed by applying a compressive load to the apical side of each slice by using a 0.7-mm-diameter cylindrical plunger attached to theupper portion of the testing machine. A crosshead speed of 0.5 mm/min was applied until bond fail- ure occurred. The load upon failure was recorded in Newton (N). The force required for dislocation of the post (bond strength) was calculated as follows: F = R/A, where F = force of displacement of the post (N), and A = bond area (mm2). Calculation of the bond area: A = π.g. (R1 + R2); where π = 3.14; g = taper of the root [g = (h2 + (R2-R1) 2) 1 / 2]; R1 represents root opening in the apex and R2 represents the root opening in the cervical. R1 and R2 were measured in Image-J (Wayne Rasband, National Institutes of Health, Bethesda, MA, USA). Thickness of the slices (h) was measured with a digital caliper. The bond strength values of the tooth slices of each group were averaged for statistical analysis. Statistical analysis The data were analyzed using a statistical software package (R, Version 0.98.490 – © 2009–2013 RStudio, Inc. USA). For comparison among chemical substances, one-way ANOVA was performed followed by a multiple comparison Tukey post hoc test. Statis- tical significance was considered as α = 5%. Results and discussion Table 1 shows the comparison among the five groups, which resulted in statistically significant differences (p < 0.001). The use of NaOCl as a chemical substance re- sulted in the lowest bond strength (p < 0.001). The same trend occurred with both groups with EDTA (either with NaOCl or CHX; p < 0.001). The group where CHX was used alone resulted in the same bond strength values as the control group (NaCl; p = 0.455). The use of 2% CHX gel did not affect the bond strength of the cement tested. However, the use of CHX gel with a final irrigation with 17% EDTA Jardim et al. Applied Adhesion Science Page 4 of 6 2014, 2:20 http://www.appliedadhesionscience.com/content/2/1/20 Table 1 Mean ± standard deviations push-out bond strength of glass fiber posts (in MPa) Substance Push-out Control 14.0 ± 8.1 A NaOCl 5.3 ± 3.3 B Chlorhexidine 9.6 ± 4.6 A EDTA + NaOCl 8.7 ± 4.8 B EDTA + Chlorhexidine 5.4 ± 2.7 B Upper case letter represents statistically significant differences among irrigants (p < 0.05). significantly reduced the bond strength. The use of 5.25% NaOCl negatively affec- ted the bond strength of the cement tested, either with or without a final irrigation with 17% EDTA. The use of 5.25% NaOCl for chemo-mechanical preparation of root canals, either with or without a final irrigation with 17% EDTA, presented statistically significant de- crease on the bond strength of fiber post cemented with self-adhesive resin cement. The efficiency of adhesive systems is directly related to the dentin quality and collagen integrity. The fact that NaOCl is an efficient organic solvent that causes dissolution of dentin collagen fibrils [12,16] might explain its negative influence on the bond strength of the self-adhesive resin cement shown in this study, since collagen plays an important role in the formation of the hybrid layer. CHX gel has been widely used in endodontics and one of its most important features is not affecting the dentin collagen matrix [12]. The results of the present study indi- cate that 2% CHX gel does not interfere with the bond strength of self-adhesive resin cements. On the other hand,it has been shown that when CHX solution was used as cavity cleanser, the residual solution and moisture contamination might be able to interfere with the bonding of RelyX Unicem to dentin, resulting in lower bond strengths [14]. Nevertheless, it is important to highlight that in the present study, CHX was used as a gel auxiliary to the root canal biochemical preparation and not as cavity cleanser solution. The final application of 17% EDTA after chemo-mechanical preparation with 2% CHX gel significantly reduced the bond strength. The application of EDTA reduces the Ca ions available on the surface of the canal walls; therefore, the potential chemical bonding that would be expected with self-adhesive resin cements is compromised af- fecting the final bond strength. The probable explanation is that the smear layer re- moval, promoted by the application of EDTA, facilitates resinous monomer penetration into the dentinal tubules [17]. Self-adhesive resin cements present a series of advantages on the bond of fiber posts, e.g. reduced clinical chair time, as they do not require any pre-treatment of the dental substrate, and elimination of the following steps: priming and air-drying for solvent evaporation [18-20]. However, the results of the present study showed that 5.25% NaOCl, either with or without 17% EDTA, affected the bond strength between self- adhesive resin cement and root canal dentin. Eventually, 2% CHX gel promoted a more favorable condition to the cementation of fiber posts with self-adhesive resin cement than 5.25% NaOCl, and should be preferred in the root canal biomechanical prepa- ration, without a final application of 17% EDTA, when a fiber post is planned to be cemented with self-adhesive resin cement. Jardim et al. Applied Adhesion Science Page 5 of 6 2014, 2:20 http://www.appliedadhesionscience.com/content/2/1/20 Conclusion The use of 2% chlorhexidine gel resulted on retention of fiber posts luted using a self- adhesive cement statistically similar to the control group (p = 0.418), which was higher than the other groups. A final irrigation with 17% EDTA significantly reduced on the retention of fiber posts luted using a self-adhesive cement. The use of 5.25% NaOCl negatively affected the bond strength, either with or without a final irrigation with 17% EDTA. Competing interests The authors declare that they have no competing interests. Authors’ contributions RCJ and TPC contributed to study design, data interpretation, manuscript drafting and critical revision; CFB and ACAF participated in the specimen preparation, laboratory analyses, data collection and manuscript drafting; PSJ participated in the study design, supervision of laboratory research, data interpretation, manuscript drafting and critical revision. All authors read and approved the final manuscript. Author details Department of Operative Dentistry, School of Dentistry, Federal University of Pelotas, Pelotas, RS, Brazil. Department of Semiology and Clinics, School of Dentistry, Federal University of Pelotas, Pelotas, RS, Brazil. Received: 13 November 2013 Accepted: 30 January 2014 Published: 04 Aug 2014 References 1. de Moraes AP, Cenci MS, Moraes RR, Pereira-Cenci T (2013) Current concepts on the use and adhesive bonding of glass-fiber posts in dentistry: a review. Appl Adhes Sci 1:4. doi:10.1186/2196-4351-1-4 2. Iglesia-Puig MA, Arellano-Cabornero A (2004) Fiber-reinforced post and core adapted to a previous metal ceramic crown. J Prosthet Dent 91:191–194. doi:10.1016/j.prosdent.2003.11.004 3. Grandini S, Goracci C, Monticelli F, Borracchini A, Ferrari M (2005) SEM evaluation of the cement layer thickness after luting two different posts. J Adhes Dent 7:235–240. doi:10.3290/j.jad.a10486 4. Farina AP, Cecchin D, Barbizam JV, Carlini-Júnior B (2011) Influence of endodontic irrigants on bond strength of a self-etching adhesive. Aust Endod J 37:26–30. doi:10.1111/j.1747-4477.2010.00249.x 5. Gomes BP, Ferraz CC, Vianna ME, Berber VB, Teixeira FB, Souza-Filho FJ (2001) In vitro antimicrobial activity of several concentrations of sodium hypochlorite and chlorhexidine gluconate in the elimination of Enterococcus faecalis. Int Endod J 34:424–428 6. Stojicic S, Zivkovic S, Qian W, Zhang H, Haapasalo M (2010) Tissue dissolution by sodium hypochlorite: effect of concentration, temperature, agitation, and surfactant. J Endod 36:1558–1562. doi:10.1016/ j.joen.2010.06.021 7. Shenoy A, Mandava P, Bolla N, Raj S, Kurien J, Prathap MS (2013) Antibacterial efficacy of sodium hypochlorite with a novel sonic agitation device. Indian J Dent Res 24:537–541. doi:10.4103/0970-9290.123361 8. Dametto FR, Ferraz CC, Gomes BP, Zaia AA, Teixeira FB, de Souza-Filho FJ (2005) In vitro assessment of the immediate and prolonged antimicrobial action of chlorhexidine gel as an endodontic irrigant against Enterococcus faecalis. Oral Surg Oral Med Oral Pathol Oral Radiol Endod 99:768–772. doi:10.1016/ j.tripleo.2004.08.026 9. Gomes BP, Vianna ME, Zaia AA, Almeida JF, Souza-Filho FJ, Ferraz CC (2013) Chlorhexidine in endodontics. Braz Dent J 24:89–102. doi:10.1590/0103-6440201302188 10. Johal S, Baumgartner JC, Marshall JG (2007) Comparison of the antimicrobial efficacy of 1.3% NaOCl/BioPure MTAD to 5.25% NaOCl/15% EDTA for root canal irrigation. J Endod 33:48–51. doi:10.1016/j.joen.2006.08.007 11. Arslan H, Yılmaz CB, Karatas E, Barutcigil C, Topcuoglu HS, Yeter KY (2013) Efficacy of different treatments of root canal walls on the pull-out bond strength of the fiber posts. Lasers Med Sci, doi:10.1007/ s10103-013-1457-4 12. Moreira DM, Almeida JF, Ferraz CC, Gomes BP, Line SR, Zaia AA (2009) Structural analysis of bovine root dentin after use of different endodontics auxiliary chemical substances. J Endod 35:1023–1027. doi:10.1016/ j.joen.2009.04.002 13. Moodley D, Grobler SR (2002) Dentine bonding agents–a review of adhesion to dentine. J South Afr Dent Assoc 57:234–238 14. Hiraishi N, Yiu CK, King NM, Tay FR (2010) Effect of chlorhexidine incorporation into a self-etching primer on dentine bond strength of a luting cement. J Dent 38:496–502. doi:10.1016/j.jdent.2010.03.005 15. Gerth HU, Dammaschke T, Zuchner H, Schäfer E (2006) Chemical analysis and bonding reaction of RelyX Unicem and Bifix composites—a comparative study. Dent Mater 22:934–941. doi:10.1016/j.dental.2005.10.004 16. Ishizuka T, Kataoka H, Yoshioka T, Suda H, Iwasak N, Takahashi H, Nishimura F (2001) Effect of NaOCl treatment on bonding to root canal dentin using a new evaluation method. Dent Mater J 20:24–33 17. Miyasak K, Nakabayashi N (1999) Combination of EDTA conditioner and Phenyl-HEMA self-etching primer for bonding to dentin. Dent Mater 15:153–157. doi:10.1016/S0300-5712(99)00025-1 Jardim et al. Applied Adhesion Science Page 6 of 6 2014, 2:20 http://www.appliedadhesionscience.com/content/2/1/20 18. Faria-e-Silva AL, Pedrosa-Filho CF, Menezes MS, Silveira DM, Martins LR (2009) Effect of relining on fiber post retention to root canal. J Appl Oral Sci 17:600–604. doi:10.1590/S1678-77572009000600012 19. Kececi AD, Ureyen KB, Adanir N (2008) Micro push-out bond strengths of four fiber-reinforced composite post systems and 2 luting materials. Oral Surg Oral Med Oral Pathol Oral Radiol Endod 105:121–128. doi:10.1016/ j.tripleo.2007.07.011 20. Radovic I, Monticelli F, Goracci C, Vulicevic ZR, Ferrari M (2008) Self-adhesive resin cements: a literature review. J Adhes Dent 10:251–258. doi:10.3290/j.jad.a13735 10.1186/2196-4351-2-20 Cite this article as: Jardim et al.: The effect of endodontic chemicals on the retention of fiber posts luted using a self-adhesive cement. Applied Adhesion Science 2014, 2:20 Submit your manuscript to a journal and benefi t from: 7 Convenient online submission 7 Rigorous peer review 7 Immediate publication on acceptance 7 Open access: articles freely available online 7 High visibility within the fi eld 7 Retaining the copyright to your article Submit your next manuscript at 7 springeropen.com

Journal

Applied Adhesion ScienceSpringer Journals

Published: Aug 4, 2014

References