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A Fluid Filtration Comparison of Gutta-Percha versus Resilon, a New Soft Resin Endodontic Obturation System
Basic Research—Technology
A Fluid Filtration Comparison of Gutta-Percha versus Resilon, a New Soft Resin Endodontic Obturation System Ryan K. Stratton, DMD, Michael J. Apicella, DDS, and Pete Mines, DDS Abstract The purpose of this study was to compare the sealing ability of gutta-percha and AH Plus sealer versus Resilon and Epiphany Resin Root Canal sealer using three different final irrigants with the fluid filtration model. There were 140 teeth prepared using a crown-down method to a size 50 file. The teeth were randomly divided into two groups: (A) GP and AH Plus and (B) Resilon and Epiphany. After removal of the smear layer each group was irrigated with either 5.25% NaOCl, 0.012% chlorhexidine (CHX), or 2% CHX for 10 minutes. Obturation was performed using the continuous wave of condensation. The teeth were stored for 20 days in 100% humidity before testing. Two-way ANOVA analysis indicated significantly less leakage (p ⬍ 0.05) using Resilon with Epiphany sealer compared to gutta-percha and AH Plus sealer. There was no statistical significance between any of the irrigants used for either obturation group. (J Endod 2006;32: 642– 645)
Key Words Fluid filtration, irrigation, obturation, Resilon
From the US Army, Ft. Bragg Endodontic Residency, Ft. Bragg, North Carolina. Address requests for reprint to Ryan K. Stratton, DMD, 7120 Brandon Dr., Temple, TX 76502. E-mail address: [email protected]. 0099-2399/$0 - see front matter Published by Elsevier Company on behalf of the American Association of Endodontists. doi:10.1016/j.joen.2005.09.002
A
pical periodontitis is caused by intracanal bacteria (1–3). Biologic necessity requires the elimination of organic remnants, bacteria, and bacterial toxins that emanate from necrotic and gangrenous root canals (4). Thus, the goal of endodontic therapy is to eliminate microbial challenges through mechanical and chemical means (5, 6) and develop a fluid-tight seal (7). The goal of attaining a complete seal, which Grossman (8) lists as one of the requirements of obturation, has not been achieved by the current obturation materials or techniques to date. Swanson and Madison (9) examined coronal microleakage in single-rooted extracted endodontically treated teeth, and found that all experimental teeth were contaminated from 79 to 85% of the root length when exposed to saliva. Torabinejad et al. (10) also demonstrated the high incidence of coronal microbial penetration by demonstrating leakage of 50% of the teeth along the entire root surface within 19 to 42 days depending on the microorganism. Therefore, the quality of the coronal seal has been shown to be just as important as the technical quality of the root filling for periapical health after root canal therapy (11). Gutta-percha has universally been accepted as the gold standard for root canal filling materials. It appears to be the least toxic and tissue-irritating root canal filling material available. However, gutta-percha does not adhere to the dentinal walls and consequently, a sealing agent is required (12). Ishley and ElDeeb (13) demonstrated that when sealer was not used with thermomechanical condensation techniques, guttapercha leakage increased 5- to 20-fold. Resin bonded root canal filling materials have been suggested as an alternative to the traditional gutta-percha based system to obtain a better seal (14, 15). However, all bonding agents and resins studied to date as root filling materials have had problems in shrinkage upon polymerization, lack of apical control and retreatability when used for endodontic purposes (14). Resilon (Resilon Research, LLC, Madison, CT) is a thermoplastic synthetic polymer-based root canal filling material. Based on polymers of polyester, Resilon contains bioactive glass and radiopaque fillers. It performs like gutta-percha, has similar handling properties, and for retreatment purposes may be softened with heat, or dissolved with solvents such as chloroform. The sealer, Epiphany Root Canal Sealant (Pentron Clinical Technologies) is a dual curable dental resin composite sealer (15). The manufacturer, Pentron Clinical Technologies, recommends that EDTA or chlorhexidine (CHX) be used as the final irrigant, as they feel that sodium hypochlorite or hydrogen peroxide may weaken the seal. The purpose of this study was to compare the amount of leakage, using the fluid filtration model, of gutta-percha and AH Plus sealer to that of Resilon and Epiphany Root Canal Sealant using three different final irrigants: 5.25% NaOCl, 0.12% CHX, or 2% CHX.
Materials and Methods There were 140 single canal straight-rooted teeth stored in 0.9% saline used for this study. The external surfaces of the roots were cleaned with curettes to remove any remaining debris and/or calculus with attention not to damage the root surface. The crowns were removed with carborundum disks (Keystone Industries, Ft. Meyers, FL) leaving approximately 16 mm of root from the coronal surface to the apex of the root. A surgical operating microscope (Global Surgical, St. Louis, MO) was used to inspect the teeth for cracks and fractures under 8⫻ magnification. All procedures were completed by one investigator. Working length was established by placing a #10 file (Henry Schein Inc., Melville, NY) into the canal until visible at the apical foramen
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Basic Research—Technology
Figure 1. Bar graph of the fluid flow (i.e. microleakage) around sealed root canal fillings demonstrating relationship of obturation materials (Resilon, Gutta-percha) with final irrigants (5.25% NaOCl, 0.12% CHX, 2.0% CHX). Resilon leaked significantly less than gutta-percha regardless of final irrigant used. Fluid flow measured in L/min⫺1 䡠 cm/H20⫺1. Groups identified by different letters are significantly different (p ⬍ 0.05).
and subtracting 1 mm. Gates Glidden burs #2 through 4 (Dentsply Tulsa Dental, Tulsa, OK) were used to prepare the coronal 6 mm of each root. Instrumentation was completed in a crown-down technique using Profile ISO series 0.06 taper rotary files until a size 50 file reached working length. An apical stop was confirmed by placing a #50 Flex-R file (Moyco Union Broach, York, PA) to working length. Patency was maintained by passing a #10 file through the apical foramen during instrumentation. RC Prep (Premier, Plymouth, PA) served as lubrication during the cleaning and shaping; and 1 ml of 5.25% sodium hypochlorite (NaOCl) was used to irrigate the canals between each file with a 27 gauge Monoject needle (Kendall, Tyco Healthcare). The smear layer was removed by using 3 ml of 17% EDTA (Pulpdent Corp., Watertown, MA) for 3 minutes followed by 3 ml of NaOCl for 3 minutes. The roots were randomly divided into three groups of 40, and the remaining 20 roots served as controls. Each group was irrigated with 3 ml of one of the following solutions for 10 minutes: Group 1, 5.25% NaOCl; group 2, 0.12% CHX gluconate (Peridex, TEVA Pharmaceuticals, Sellersville, PA); and group 3, 2% CHX gluconate (Hibiclens, Regent Medical, Norcross, GA). The 2% CHX prepared by diluting 4% CHX gluconate (Hibiclens) with sterile saline in a 1:1 solution. After the final rinse, the canals were dried using coarse paper points (Henry Schein Inc.). Each group was further subdivided into the following obturation groups of 20 roots each: Group A, gutta-percha with AH Plus sealer (Dentsply DeTrey, Konstanz, Germany); and group B, Resilon with Epiphany resin root canal sealer (Pentron, Wallingford, CT). All groups were obturated using the continuous wave of condensation technique (System B, Analytic Endodontics, Orange, CA) in the following manner. Group A: 0.06 tapered ISO size 50 master gutta-percha (Dia Dent, Seoul, Korea) was coated with a thin layer of AH Plus sealer, mixed according to manufacturer’s instructions, and placed into the canal at working length. A 0.08 taper System B Plugger (Analytic Endodontics, Orange, CA) set at 200°C was introduced into the canal. The tip of the plugger was activated and condensation was terminated within 3 mm of working length. The plugger was held in position for 10 seconds before the System B was activated for 1 second and withdrawn from the tooth. A 5/7 plugger (Hu-Friedy, Chicago, IL) was placed into the canal to confirm seating. The remainder of the canal was backfilled with gutta-percha using the Obtura II (Obtura, Fenton, MO) set at 200°C. Group B:
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Epiphany primer was placed into the canals with a microbrush (Microbrush International, Grafton, WI) for 30 seconds, and the excess was removed with coarse paper points. A size 50 0.06 taper master Resilon cone was coated with a thin layer of Epiphany sealer, mixed to manufacturer’s directions with no thinning resin, and placed at working length. The System B was reduced to 175°C and the Obtura II to 180°C when using the Epiphany pellets as recommended by the manufacturer. The canals were obturated in the same manner as the gutta-percha. After obturation, each root was lightcured for 40 seconds to form the initial coronal seal. Positive controls consisted of two groups of 10 teeth each obturated with either gutta-percha or Resilon with no sealer, respectively. The negative control was a stainless steel tube mounted halfway into a solid plexiglass block to ensure that there were no leaks in the system. All roots were radiographed buccal-lingually to ensure the obturation material was placed completely throughout the canal. The teeth were stored in 100% humidity at 37°C for 20 days to allow for complete setting of the sealer. Using the fluid-filtration method described by Ciucchi et al. (16), the roots were mounted on plexiglass blocks with viscous cyanoacrylate cement (Fill-It, American Dental Supply, Easton, PA). The plexiglass blocks were penetrated by an 18 gauge stainless steel tubes that permitted water to be introduced into the coronal portion of the roots. Leakage was measured using a Fisher Scientific mm ruler at 10 psi. Fluid flow rates (i.e. leakage) were expressed as L/min⫺1 䡠 cm/H20⫺1. A twoway ANOVA statistical analysis was performed to compare leakage of the obturated canals. The level of significance was set at ␣ ⬍ 0.05.
Results The leakage of the negative control, measured by the fluid filtration model, was uniformly zero, and the leakage of the positive controls were all immeasurably high. Statistical analysis indicated that there was significantly less leakage (p ⬍ 0.05) with the Resilon based system compared to gutta-percha and AH Plus sealer (Fig. 1). There was no statistically significant difference in leakage between irrigants. Although there was no statistical difference between the irrigants used with either obturation material, there was a trend towards more leakage with the Resilon material when the final irrigant used was NaOCl (Fig. 1).
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Basic Research—Technology Discussion The results of this study showed that the Resilon based system created a significantly better seal than gutta-percha and AH-Plus when used with the continuous wave of condensation. Furthermore, the use of different irrigating solutions did not significantly affect Resilon’s sealing ability. Chlorhexidine is a cationic bisbiguanide (17) and has become recognized as an effective oral antimicrobial agent in periodontal therapy, caries prevention, and the treatment of oral infections (18). It has the ability to adsorb into dentin to provide continuous antimicrobial activity over a period of 48 to 72 hours (19, 20); and Filho (21) found that a solution of 2% CHX produced the same inflammatory response as phosphate-buffered saline in mice. Ferguson (22) showed that CHX gluconate (0.12%), when used as an irrigant, had no long-term detrimental effects on the apical seal. Sodium hypochlorite is used for the gross debridement, lubrication, destruction of microbes, dissolution of tissues, removal of the collagen layer, and dehydration of dentin (23). However, it had been shown to adversely affect the bond strengths of composite resins to dentin after endodontic treatment (24). Furthermore, residual chemical irrigants are likely to diffuse into the dentin and dentinal tubules and may contaminate the surface, which may effect the penetration of resin into the dentin structure or the polymerization of the monomer (25). Erdemir et al. (25) compared the bond strengths of C&B Metabond on human dentin using several different irrigating solutions. They found significantly reduced bond strengths when using either 5% sodium hypochlorite, 3% hydrogen peroxide, or a combination of both; however teeth irrigated with 0.2% CHX had significantly increased bond strength. Diluted Hibiclens was used as an irrigant because Peridex has a low concentration of CHX gluconate; 2% CHX is currently marketed as Consepsis (Ultradent, South Jordan, UT). It was thought that Hibiclens diluted to half-strength may be an efficient and economical way of obtaining 2% CHX in the office; with the concern that components in Hibiclens could have an adverse effect on sealing ability. The results of this study were consistent with several studies by Shipper and co-workers (15). In their first study, the authors tested resistance to bacterial penetration using Streptococccus mutans or Enterococus faecalis using the Resilon/Epiphany system in extracted single-rooted teeth, and compared it to gutta-percha and AH26 sealer filled roots over a 30-day period. Their study showed that the guttapercha group allowed bacterial penetration in a high proportion of the cases, while the Resilon group resisted bacterial penetration. The authors contributed the excellent sealing ability to the monoblock that is created when using Resilon with Epiphany sealer as opposed to guttapercha and AH 26 sealer. In a follow-up study by Shipper et al. (26), a dog model was used to compare, in vivo, the efficacy of gutta-percha and AH 26 sealer versus Resilon with Epiphany primer and sealer in preventing apical periodontitis subsequent to coronal inoculation with oral microorganisms over a period of 14 weeks. The authors concluded that the Resilon based system was associated with less apical periodontitis than gutta-percha and AH26 sealer. In contrast to the above studies is a study by Tay et al. (27). In this study the authors compared the Resilon/Epiphany system to gutta-percha and AH Plus sealer. Apical leakage was measured using a silver tracer technique and the sections were observed under transmission electron microscopy (TEM). They also used scanning microscopy (SEM) to examine for gaps along the canal walls. SEM analysis showed gap-free and gap-containing regions with both root canal filling techniques in the apical 4 mm of each canal. Furthermore, there was no difference in leakage in the apical 4 mm with either root canal filling material. Possible reasons for the different results could be with the model used in each study. Both of Shipper’s 644
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studies dealt with coronal leakage, while Tay’s study was a measure of apical leakage. It is possible that the bonding systems may be more effective in the coronal portion of the canal, but not as effective in the apical portion of the root. The results obtained with the fluid filtration used in this study may reflect a combination of both apical and coronal leakage. Under the conditions of this study, the Resilon groups with selfetch primer and Epiphany resin root canal sealer were significantly more resistant to fluid movement than the gutta-percha and AH Plus sealer groups. Although not significant, when sodium hypochlorite was used as a final irrigant with Resilon and Epiphany sealer there was a trend to more leakage. It can be concluded from this study that Resilon with Epiphany sealer provides a better seal than gutta-percha and AH Plus sealer when using the continuous wave of condensation technique. Furthermore, the use of different irrigants has little effect on the apical seal. Even with the apparent short-term sealing quality of Resilon with Epiphany sealer, long-term clinical studies are needed to determine if outcome studies support the use of this material.
Acknowledgment Thanks to Dr. David Pashley and Kelli Agee for their help in providing statistical support for this study. This study is the work of the United States government and may be reprinted without permission. Opinions expressed herein, unless otherwise indicated, are those of the authors. They do not represent the views of the Department of the Army or any other Department of Agency of the United States Government.
References 1. Kakehashi S, Stanley H, Fitzgerald R. The effect of surgical exposures of dental pulps in germ-free and conventional laboratory rats. Oral Surg Oral Med Oral Pathol 1965;20:340 –9. 2. Bergenholtz G. Micro-organisms from necrotic pulp of traumatized teeth. Odontol Revy 1974;25:347–58. 3. Möller AJ, Fabricius L, Dahlén G, Ohman AE, Heyden G. Influence on periradicular tissues of indigenous oral bacteria and necrotic pulp tissue in monkeys. Scand J Dent Res 1981;89:475– 84. 4. Schilder H. Filling root canals in three dimensions. Dent Clin North Am 1967;723– 44. 5. Byström A, Sundqvist G. Bacteriologic evaluation of the effect of 0.5 percent sodium hypochlorite in endodontic therapy. Oral Surg Oral Med Oral Pathol 1983;55:307–12. 6. Byström A, Sundqvist G. The antibacterial action of sodium hypochlorite and EDTA in 60 cases of endodontic therapy. Int Endod J 1985;18:35– 40. 7. Grossman LI. Endodontic practice, 6th ed. Philadelphia, Lea & Febiger, 1966. 8. Grossman LI. Endodontic practice, 10th ed. Philadelphia, Lea & Febiger 1981;297. 9. Swanson K, Madison S. An evaluation of coronal microleakage in endodontically treated teeth. Part I. Time periods. J Endod 1987;13:56 –9. 10. Torabinejad M, Ung B, Kettering JD. In vitro bacterial penetration of coronally unsealed endodontically treated teeth. J Endod 1990;16:566 –9. 11. Ray HA, Trope M. Periapical status of endodontically treated teeth in relation to the technical quality of the root filling and the coronal restoration. Int Endod J 1995;28:12– 8. 12. Spangberg L, Langeland K. Biologic effects of dental material. 1. Toxicity of root canal filling materials on HeLa cells in vitro. Oral Surg Oral Med Oral Pathol 1973;35:402–14. 13. Ishley DJ, ElDeeb ME. An in vitro assessment of the quality of apical seal of thermomechanically obturated canals with and without sealer. J Endod 1983;9:242–5. 14. Imai Y, Komabayashi T. Properties of a new injectable type of root canal filling resin with adhesiveness to dentin. J Endod 2003;29:20 –3. 15. 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. 16. Ciucchi B, Bouillaguet S, Holz J, Pashley D. Dentinal fluid dynamics in human teeth, in vivo. J Endod 1995;21:191– 4. 17. Wuerch RMW, Apicella MJ, Mines P, Yancich PJ, Pashley DH. Effect of 2% chlorhexidine gel as an intracanal medication on the apical seal of the root-canal system. J Endod 2004;30:788 –91.
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Basic Research—Technology 18. Jeansonne MJ, White RR. A Comparison of 2.0% chlorhexidine gluconate and 5.25% sodium hypochlorite as antimicrobial endodontic irrigants. J Endod 1994;20:276 –78. 19. Lenet BJ, Komorowski R, Yu Wu X, et al. Antimicrobial substantivity of bovine root dentin exposed to different chlorhexidine delivery vehicles. J Endod 2000;26:652–5. 20. White RR, Hays GL, Jane LR. Residual antimicrobial activity after canal irrigation with chlorhexidine. J Endod 1997;23:229 –31. 21. Filho MT, Leonardo MR, Silva LA, Aníbal FF, Faccioli LH. Inflammatory response to different endodontic irrigating solutions. Int Endod J 2002;35:735–9. 22. Ferguson DB, Marley JT, Hartwell GR. The effect of chlorhexidine gluconate as an endodontic irrigant on the apical seal: long-term results. J Endod 2003;29:91– 4.
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23. Gutmann JL. The dentin-root complex: anatomic and biologic considerations in restoring endodontically treated teeth. J Prosthet Dent 1992;67:458 – 67. 24. Ozturk B, Özer F. Effect of NaOCl on bond strengths of bonding agents to pulp chamber lateral walls. J Endod 2004;30:362–5. 25. Erdemir A, Ari H, Güngünes H, Belli S. Effect of medications for root canal treatment on bonding to root canal dentin. J Endod 2004;30:113– 6. 26. 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. 27. Tay FR, Loushine RJ, Weller RN, et al. Ultrastructural evalusation of the apical seal in roots filled with a polycaprolactone-based root canal filling material. J Endod 2005; 31:514 –9.
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A Fluid Filtration Comparison of Gutta-Percha versus Resilon, a New Soft Resin Endodontic Obturation System Ryan K. Stratton, DMD, Michael J. Apicella, DDS, and Pete Mines, DDS Abstract The purpose of this study was to compare the sealing ability of gutta-percha and AH Plus sealer versus Resilon and Epiphany Resin Root Canal sealer using three different final irrigants with the fluid filtration model. There were 140 teeth prepared using a crown-down method to a size 50 file. The teeth were randomly divided into two groups: (A) GP and AH Plus and (B) Resilon and Epiphany. After removal of the smear layer each group was irrigated with either 5.25% NaOCl, 0.012% chlorhexidine (CHX), or 2% CHX for 10 minutes. Obturation was performed using the continuous wave of condensation. The teeth were stored for 20 days in 100% humidity before testing. Two-way ANOVA analysis indicated significantly less leakage (p ⬍ 0.05) using Resilon with Epiphany sealer compared to gutta-percha and AH Plus sealer. There was no statistical significance between any of the irrigants used for either obturation group. (J Endod 2006;32: 642– 645)
Key Words Fluid filtration, irrigation, obturation, Resilon
From the US Army, Ft. Bragg Endodontic Residency, Ft. Bragg, North Carolina. Address requests for reprint to Ryan K. Stratton, DMD, 7120 Brandon Dr., Temple, TX 76502. E-mail address: [email protected]. 0099-2399/$0 - see front matter Published by Elsevier Company on behalf of the American Association of Endodontists. doi:10.1016/j.joen.2005.09.002
A
pical periodontitis is caused by intracanal bacteria (1–3). Biologic necessity requires the elimination of organic remnants, bacteria, and bacterial toxins that emanate from necrotic and gangrenous root canals (4). Thus, the goal of endodontic therapy is to eliminate microbial challenges through mechanical and chemical means (5, 6) and develop a fluid-tight seal (7). The goal of attaining a complete seal, which Grossman (8) lists as one of the requirements of obturation, has not been achieved by the current obturation materials or techniques to date. Swanson and Madison (9) examined coronal microleakage in single-rooted extracted endodontically treated teeth, and found that all experimental teeth were contaminated from 79 to 85% of the root length when exposed to saliva. Torabinejad et al. (10) also demonstrated the high incidence of coronal microbial penetration by demonstrating leakage of 50% of the teeth along the entire root surface within 19 to 42 days depending on the microorganism. Therefore, the quality of the coronal seal has been shown to be just as important as the technical quality of the root filling for periapical health after root canal therapy (11). Gutta-percha has universally been accepted as the gold standard for root canal filling materials. It appears to be the least toxic and tissue-irritating root canal filling material available. However, gutta-percha does not adhere to the dentinal walls and consequently, a sealing agent is required (12). Ishley and ElDeeb (13) demonstrated that when sealer was not used with thermomechanical condensation techniques, guttapercha leakage increased 5- to 20-fold. Resin bonded root canal filling materials have been suggested as an alternative to the traditional gutta-percha based system to obtain a better seal (14, 15). However, all bonding agents and resins studied to date as root filling materials have had problems in shrinkage upon polymerization, lack of apical control and retreatability when used for endodontic purposes (14). Resilon (Resilon Research, LLC, Madison, CT) is a thermoplastic synthetic polymer-based root canal filling material. Based on polymers of polyester, Resilon contains bioactive glass and radiopaque fillers. It performs like gutta-percha, has similar handling properties, and for retreatment purposes may be softened with heat, or dissolved with solvents such as chloroform. The sealer, Epiphany Root Canal Sealant (Pentron Clinical Technologies) is a dual curable dental resin composite sealer (15). The manufacturer, Pentron Clinical Technologies, recommends that EDTA or chlorhexidine (CHX) be used as the final irrigant, as they feel that sodium hypochlorite or hydrogen peroxide may weaken the seal. The purpose of this study was to compare the amount of leakage, using the fluid filtration model, of gutta-percha and AH Plus sealer to that of Resilon and Epiphany Root Canal Sealant using three different final irrigants: 5.25% NaOCl, 0.12% CHX, or 2% CHX.
Materials and Methods There were 140 single canal straight-rooted teeth stored in 0.9% saline used for this study. The external surfaces of the roots were cleaned with curettes to remove any remaining debris and/or calculus with attention not to damage the root surface. The crowns were removed with carborundum disks (Keystone Industries, Ft. Meyers, FL) leaving approximately 16 mm of root from the coronal surface to the apex of the root. A surgical operating microscope (Global Surgical, St. Louis, MO) was used to inspect the teeth for cracks and fractures under 8⫻ magnification. All procedures were completed by one investigator. Working length was established by placing a #10 file (Henry Schein Inc., Melville, NY) into the canal until visible at the apical foramen
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Figure 1. Bar graph of the fluid flow (i.e. microleakage) around sealed root canal fillings demonstrating relationship of obturation materials (Resilon, Gutta-percha) with final irrigants (5.25% NaOCl, 0.12% CHX, 2.0% CHX). Resilon leaked significantly less than gutta-percha regardless of final irrigant used. Fluid flow measured in L/min⫺1 䡠 cm/H20⫺1. Groups identified by different letters are significantly different (p ⬍ 0.05).
and subtracting 1 mm. Gates Glidden burs #2 through 4 (Dentsply Tulsa Dental, Tulsa, OK) were used to prepare the coronal 6 mm of each root. Instrumentation was completed in a crown-down technique using Profile ISO series 0.06 taper rotary files until a size 50 file reached working length. An apical stop was confirmed by placing a #50 Flex-R file (Moyco Union Broach, York, PA) to working length. Patency was maintained by passing a #10 file through the apical foramen during instrumentation. RC Prep (Premier, Plymouth, PA) served as lubrication during the cleaning and shaping; and 1 ml of 5.25% sodium hypochlorite (NaOCl) was used to irrigate the canals between each file with a 27 gauge Monoject needle (Kendall, Tyco Healthcare). The smear layer was removed by using 3 ml of 17% EDTA (Pulpdent Corp., Watertown, MA) for 3 minutes followed by 3 ml of NaOCl for 3 minutes. The roots were randomly divided into three groups of 40, and the remaining 20 roots served as controls. Each group was irrigated with 3 ml of one of the following solutions for 10 minutes: Group 1, 5.25% NaOCl; group 2, 0.12% CHX gluconate (Peridex, TEVA Pharmaceuticals, Sellersville, PA); and group 3, 2% CHX gluconate (Hibiclens, Regent Medical, Norcross, GA). The 2% CHX prepared by diluting 4% CHX gluconate (Hibiclens) with sterile saline in a 1:1 solution. After the final rinse, the canals were dried using coarse paper points (Henry Schein Inc.). Each group was further subdivided into the following obturation groups of 20 roots each: Group A, gutta-percha with AH Plus sealer (Dentsply DeTrey, Konstanz, Germany); and group B, Resilon with Epiphany resin root canal sealer (Pentron, Wallingford, CT). All groups were obturated using the continuous wave of condensation technique (System B, Analytic Endodontics, Orange, CA) in the following manner. Group A: 0.06 tapered ISO size 50 master gutta-percha (Dia Dent, Seoul, Korea) was coated with a thin layer of AH Plus sealer, mixed according to manufacturer’s instructions, and placed into the canal at working length. A 0.08 taper System B Plugger (Analytic Endodontics, Orange, CA) set at 200°C was introduced into the canal. The tip of the plugger was activated and condensation was terminated within 3 mm of working length. The plugger was held in position for 10 seconds before the System B was activated for 1 second and withdrawn from the tooth. A 5/7 plugger (Hu-Friedy, Chicago, IL) was placed into the canal to confirm seating. The remainder of the canal was backfilled with gutta-percha using the Obtura II (Obtura, Fenton, MO) set at 200°C. Group B:
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Epiphany primer was placed into the canals with a microbrush (Microbrush International, Grafton, WI) for 30 seconds, and the excess was removed with coarse paper points. A size 50 0.06 taper master Resilon cone was coated with a thin layer of Epiphany sealer, mixed to manufacturer’s directions with no thinning resin, and placed at working length. The System B was reduced to 175°C and the Obtura II to 180°C when using the Epiphany pellets as recommended by the manufacturer. The canals were obturated in the same manner as the gutta-percha. After obturation, each root was lightcured for 40 seconds to form the initial coronal seal. Positive controls consisted of two groups of 10 teeth each obturated with either gutta-percha or Resilon with no sealer, respectively. The negative control was a stainless steel tube mounted halfway into a solid plexiglass block to ensure that there were no leaks in the system. All roots were radiographed buccal-lingually to ensure the obturation material was placed completely throughout the canal. The teeth were stored in 100% humidity at 37°C for 20 days to allow for complete setting of the sealer. Using the fluid-filtration method described by Ciucchi et al. (16), the roots were mounted on plexiglass blocks with viscous cyanoacrylate cement (Fill-It, American Dental Supply, Easton, PA). The plexiglass blocks were penetrated by an 18 gauge stainless steel tubes that permitted water to be introduced into the coronal portion of the roots. Leakage was measured using a Fisher Scientific mm ruler at 10 psi. Fluid flow rates (i.e. leakage) were expressed as L/min⫺1 䡠 cm/H20⫺1. A twoway ANOVA statistical analysis was performed to compare leakage of the obturated canals. The level of significance was set at ␣ ⬍ 0.05.
Results The leakage of the negative control, measured by the fluid filtration model, was uniformly zero, and the leakage of the positive controls were all immeasurably high. Statistical analysis indicated that there was significantly less leakage (p ⬍ 0.05) with the Resilon based system compared to gutta-percha and AH Plus sealer (Fig. 1). There was no statistically significant difference in leakage between irrigants. Although there was no statistical difference between the irrigants used with either obturation material, there was a trend towards more leakage with the Resilon material when the final irrigant used was NaOCl (Fig. 1).
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Basic Research—Technology Discussion The results of this study showed that the Resilon based system created a significantly better seal than gutta-percha and AH-Plus when used with the continuous wave of condensation. Furthermore, the use of different irrigating solutions did not significantly affect Resilon’s sealing ability. Chlorhexidine is a cationic bisbiguanide (17) and has become recognized as an effective oral antimicrobial agent in periodontal therapy, caries prevention, and the treatment of oral infections (18). It has the ability to adsorb into dentin to provide continuous antimicrobial activity over a period of 48 to 72 hours (19, 20); and Filho (21) found that a solution of 2% CHX produced the same inflammatory response as phosphate-buffered saline in mice. Ferguson (22) showed that CHX gluconate (0.12%), when used as an irrigant, had no long-term detrimental effects on the apical seal. Sodium hypochlorite is used for the gross debridement, lubrication, destruction of microbes, dissolution of tissues, removal of the collagen layer, and dehydration of dentin (23). However, it had been shown to adversely affect the bond strengths of composite resins to dentin after endodontic treatment (24). Furthermore, residual chemical irrigants are likely to diffuse into the dentin and dentinal tubules and may contaminate the surface, which may effect the penetration of resin into the dentin structure or the polymerization of the monomer (25). Erdemir et al. (25) compared the bond strengths of C&B Metabond on human dentin using several different irrigating solutions. They found significantly reduced bond strengths when using either 5% sodium hypochlorite, 3% hydrogen peroxide, or a combination of both; however teeth irrigated with 0.2% CHX had significantly increased bond strength. Diluted Hibiclens was used as an irrigant because Peridex has a low concentration of CHX gluconate; 2% CHX is currently marketed as Consepsis (Ultradent, South Jordan, UT). It was thought that Hibiclens diluted to half-strength may be an efficient and economical way of obtaining 2% CHX in the office; with the concern that components in Hibiclens could have an adverse effect on sealing ability. The results of this study were consistent with several studies by Shipper and co-workers (15). In their first study, the authors tested resistance to bacterial penetration using Streptococccus mutans or Enterococus faecalis using the Resilon/Epiphany system in extracted single-rooted teeth, and compared it to gutta-percha and AH26 sealer filled roots over a 30-day period. Their study showed that the guttapercha group allowed bacterial penetration in a high proportion of the cases, while the Resilon group resisted bacterial penetration. The authors contributed the excellent sealing ability to the monoblock that is created when using Resilon with Epiphany sealer as opposed to guttapercha and AH 26 sealer. In a follow-up study by Shipper et al. (26), a dog model was used to compare, in vivo, the efficacy of gutta-percha and AH 26 sealer versus Resilon with Epiphany primer and sealer in preventing apical periodontitis subsequent to coronal inoculation with oral microorganisms over a period of 14 weeks. The authors concluded that the Resilon based system was associated with less apical periodontitis than gutta-percha and AH26 sealer. In contrast to the above studies is a study by Tay et al. (27). In this study the authors compared the Resilon/Epiphany system to gutta-percha and AH Plus sealer. Apical leakage was measured using a silver tracer technique and the sections were observed under transmission electron microscopy (TEM). They also used scanning microscopy (SEM) to examine for gaps along the canal walls. SEM analysis showed gap-free and gap-containing regions with both root canal filling techniques in the apical 4 mm of each canal. Furthermore, there was no difference in leakage in the apical 4 mm with either root canal filling material. Possible reasons for the different results could be with the model used in each study. Both of Shipper’s 644
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studies dealt with coronal leakage, while Tay’s study was a measure of apical leakage. It is possible that the bonding systems may be more effective in the coronal portion of the canal, but not as effective in the apical portion of the root. The results obtained with the fluid filtration used in this study may reflect a combination of both apical and coronal leakage. Under the conditions of this study, the Resilon groups with selfetch primer and Epiphany resin root canal sealer were significantly more resistant to fluid movement than the gutta-percha and AH Plus sealer groups. Although not significant, when sodium hypochlorite was used as a final irrigant with Resilon and Epiphany sealer there was a trend to more leakage. It can be concluded from this study that Resilon with Epiphany sealer provides a better seal than gutta-percha and AH Plus sealer when using the continuous wave of condensation technique. Furthermore, the use of different irrigants has little effect on the apical seal. Even with the apparent short-term sealing quality of Resilon with Epiphany sealer, long-term clinical studies are needed to determine if outcome studies support the use of this material.
Acknowledgment Thanks to Dr. David Pashley and Kelli Agee for their help in providing statistical support for this study. This study is the work of the United States government and may be reprinted without permission. Opinions expressed herein, unless otherwise indicated, are those of the authors. They do not represent the views of the Department of the Army or any other Department of Agency of the United States Government.
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Basic Research—Technology 18. Jeansonne MJ, White RR. A Comparison of 2.0% chlorhexidine gluconate and 5.25% sodium hypochlorite as antimicrobial endodontic irrigants. J Endod 1994;20:276 –78. 19. Lenet BJ, Komorowski R, Yu Wu X, et al. Antimicrobial substantivity of bovine root dentin exposed to different chlorhexidine delivery vehicles. J Endod 2000;26:652–5. 20. White RR, Hays GL, Jane LR. Residual antimicrobial activity after canal irrigation with chlorhexidine. J Endod 1997;23:229 –31. 21. Filho MT, Leonardo MR, Silva LA, Aníbal FF, Faccioli LH. Inflammatory response to different endodontic irrigating solutions. Int Endod J 2002;35:735–9. 22. Ferguson DB, Marley JT, Hartwell GR. The effect of chlorhexidine gluconate as an endodontic irrigant on the apical seal: long-term results. J Endod 2003;29:91– 4.
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23. Gutmann JL. The dentin-root complex: anatomic and biologic considerations in restoring endodontically treated teeth. J Prosthet Dent 1992;67:458 – 67. 24. Ozturk B, Özer F. Effect of NaOCl on bond strengths of bonding agents to pulp chamber lateral walls. J Endod 2004;30:362–5. 25. Erdemir A, Ari H, Güngünes H, Belli S. Effect of medications for root canal treatment on bonding to root canal dentin. J Endod 2004;30:113– 6. 26. 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. 27. Tay FR, Loushine RJ, Weller RN, et al. Ultrastructural evalusation of the apical seal in roots filled with a polycaprolactone-based root canal filling material. J Endod 2005; 31:514 –9.
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