TY - JOUR
AU - PhD, James C. McPherson, III,
AB - ABSTRACT Dental emergencies negatively affect troop readiness, especially during combat. Endodontic retreatment, when required, is especially challenging when the removal of endodontic sealer is required. In this study, we investigated the effectiveness of synthetic endodontic solvents to remove endodontic sealers. Fifty capillary tubes (2.7 mm ID × 22 mm L), each filled to 15 mm with either Roth 801, AH Plus, MetaSEAL, or gutta-percha, were stored at 75% humidity for 14 days at 37°C. Ten capillary tubes containing each sealer were treated with either chloroform, xylene, EndoSolv R, EndoSolv E, or no solvent, and then penetrated with D3 ProTaper Universal Retreatment file on the same day. The time for the file to penetrate the length of each sealer was recorded, and the data statistically analyzed. Roth 801 failed to set and was not tested. The file took 3.4 ± 0.1, 4.8 ± 0.3, 5.7 ± 0.4, 4.5 ± 0.2, and 10.6 ± 1.0 seconds (mean ± SD) to penetrate gutta-percha using chloroform, xylene, EndoSolv R, EndoSolv E, or no solvent, respectively, and was performed by one endodontic resident at one sitting. The time for penetration of gutta-percha with any solvent was significantly faster (p ≤ 0.05) than for AH Plus or MetaSEAL.The time for AH Plus ranged from 23.1 ± 1.0 to 81.5 ± 4.5 seconds. The time for MetaSEAL ranged from 97.2 ± 6.1 to >180 seconds. EndoSolv E was the most effective solvent for AH Plus. It took significantly more time to remove MetaSEAL than AH Plus, regardless of the solvent used. Our study indicated that the use of the proper endodontic solvent makes complete removal of a sealer much more effective during retreatment. INTRODUCTION The rigors of modern combat in austere environment requires soldiers be physically, mentally, and medically well prepared. Dental care is an integral part of the Army Readiness program.1 During Operation Iraqi Freedom and Operation Enduring Freedom, 20% to 25% of deployed soldiers experienced a dental emergency during their deployment.2,3 According to Liewehr,3 for an Army division, this resulted in a potential loss of 18,000 man-days during a 1-year deployment with approximately half of the procedures requiring endodontic intervention. Endodontic treatment is not without failure with 6% of all root canal requiring retreatment.4 A frequent cause of retreatment is the persistence of a microbial infection in the root canal system and/or the periradicular area,5 necessitating the removal of an old obturation. The goal of retreatment is the complete eradication of the microbial infection and infected root canal filling materials, which are often difficult to remove.6,7 The complete removal of gutta-percha and sealer is necessary to allow effective cleaning, shaping, and refilling of the root canal system. However, complete removal is not always possible.8 Endodontic sealers are used to seal voids between the core material and the root canal system and to prevent leakage from the apical area or coronal restoration. The techniques for removing root canal filling materials include the use of solvents, heat, hand files, rotary files, ultrasonic instruments, and more recently, neodymium-doped yttrium aluminum garnet laser, used either alone or in combination.7,–11 Previous studies by Hansen8 and Erdemir et al,12 evaluated the efficacy of solvents using manual instrumentation with Hedstrom files.13 Nickel–titanium rotary files were introduced for the purpose of removing root canal filling materials.14 Rotary files are more efficient than manual instrumentation.15 Advantages of rotary files include maintenance of canal shape and shorter working time. The ProTaper Universal Retreatment file,14,16 used in sequence, is designed to remove the root canal filling material utilizing different lengths, tapers, and apical tip diameters. Numerous studies have proven the efficacy of solvents in softening gutta-percha,12,17 but studies on root canal sealers have been limited to the dissolving capability of solvents.6,1 These studies do not address the mechanical relationship between the efficacy of solvents to remove, dissolve, or dislodge these materials from the dentinal wall of the root canal. Chloroform, although considered carcinogenic,18 is recognized as the most efficient solvent for root canal retreatment. Other solvents, such as xylene, halothane, eucalyptol, and orange oil, have been tested as alternative solvents.19 EndoSolv R and EndoSolv E are currently available synthetic endodontic solvents. EndoSolv R is designed to remove phenol-based resin sealers, and EndoSolv E is designed to remove zinc oxide eugenol–based sealers. The aim of this study is to determine the effectiveness of four different synthetic endodontic solvents and 1 control (no solvent) in the removal of four types of root canal sealers using automated instrumentation with the D3 ProTaper Universal Retreatment file. The time required to effectively remove all sealers is an indication of the selection of the proper solvent and the ease of the retreatment process. MATERIALS AND METHODS Endodontic sealers Roth 801 (ROTH International, Chicago, Illinois), AH Plus (DENTSPLY International, Johnson City, Tennessee), and MetaSEAL (PARKELL, Edgewood, New York) were mixed exactly according to the manufacturer's instructions and placed in sterile 5-mL plastic syringes. Using a sterile 19-gauge needle, each sealer was placed into a glass capillary tube (2.7 mm internal diameter, 22 mm long, n = 50) to a fill level of 15 mm. Each capillary tube was filled with thermoplasticized gutta-percha (Obtura II; Obtura Spartan Endodontics, Earth City, Missouri) and served as the capillary control. The tubes (4 groups of n = 50 samples; n = 200 total) were placed in a chamber with a 75% relative humidity at 37°C for 14 days to allow the materials to completely set.20 Next, 10 samples of each sealer were filled from the open capillary end with 5 mm of one of the following solvents: chloroform (Sultan Healthcare, Edgewood, New Jersey), xylene (Sultan Healthcare), EndoSolv R (SEPTODONT, New Castle, Delaware), EndoSolv E (SEPTODONT), and no solvent as the negative control. A D3 ProTaper Universal Retreatment file, rotating at 500 rpm in a handheld handpiece was used to penetrate each sealer. Care was taken to maintain consistency of the working pressure for each sample by using one endodontic resident. The solvent was refreshed continuously as needed from the open capillary end. The time for the file to penetrate the 15 mm length of sealer in each tube was recorded in seconds. If penetration was not completed in 180 seconds, the test was terminated and the time recorded. The time of penetration, the dependent variable, was recorded for each sample–solvent combination. The independent variable was the sealer and the solvent in each capillary tube. The mean and standard deviation was calculated for each group from the time recorded for each solvent. The data were analyzed using Tukey–Kramer's one-way analysis of variance. A “p” value of ≤0.05 was considered significant. RESULTS The time required for a D3 ProTaper Universal Retreatment file to penetrate the length of the sealer in each tube, for each solvent, is presented in Figure 1. There is a significant reduction (p ≤ 0.05) in the time taken to penetrate the sealer between gutta-percha and either AH Plus or MetaSEAL, regardless of the solvent used. Roth 801 was not tested because it failed to set within the test period. For gutta-percha, the use of any solvent significantly expedited penetration time, and there are no significant differences among the solvents tested. The most effective solvent for AH Plus was EndoSolv E (p ≤ 0.05). There were no significant differences among the remaining solvents and the control for AH Plus. For MetaSEAL, there was a significant difference between the control group and all solvents tested (p ≤ 0.05). The D3 ProTaper Universal Retreatment file was unable to penetrate MetaSEAL without a solvent present within 180 seconds. For MetaSEAL, there were no significant differences among the solvents tested. MetaSEAL required a significantly longer penetration time than either the AH Plus or gutta-percha groups (p ≤ 0.05). FIGURE 1. View largeDownload slide The time (seconds) required to penetrate the length of the tube. FIGURE 1. View largeDownload slide The time (seconds) required to penetrate the length of the tube. DISCUSSION Among the sealers tested, the results show significantly less time is required to remove gutta-percha compared to the either AH Plus or MetaSEAL (p ≤ 0.05; Fig. 1). A measure of the time is required to completely remove a previous root canal filling. This served as an indication of the effectiveness and ease of the sealer removal during retreatment with a shorter time serving as an indicator of the proper solvent selection. There were no significant differences in the removal of gutta-percha among the various solvents. Our results are in agreement with those of Hunter et al21 who observed similar results removing gutta-purcha, comparing chloroform, halothane, and eucalyptol while using a hand file method and a controlled 750 g force method. Our results agrees with those of Hansen8 who observed no significant difference in the ability of solvents to dissolve gutta-purcha. In combination, the data support the choice of gutta-percha, in combination with a variety of sealers, as the most commonly used material for root canal filling.19,21 EndoSolv E was the most effective solvent in removing AH Plus (p ≤ 0.05). The manufacturer markets EndoSolv R as being designed to remove resin-based sealers, although EndoSolv E is recomended to remove zinc oxide eugenol sealers, like Roth 801. However, in this study, EndoSolv R did not remove the sealers faster than the other solvents tested. We chose to use no solvent for the control to compare our results with those already in the literature. Water, saline, or solvent may have produced different results. The result of this study indicate that it was significantly faster to remove AH Plus (p ≤ 0.05) than MetaSEAL with any solvent or no solvent. Our results are in conflict with those of Erdemir et al12 who reported AH Plus tightly adapted to the tube walls and that chloroform was ineffective in removal of the sealer from the tube within 30 minutes. In our study, a difference in the glass tube composition may have resulted in a less tight adaptation of AH Plus to the tube wall and resulted in complete removal of the sealer. MetaSEAL, a recently introduced dual-curable methacrylate resin-based sealer has characterictics of potential bondability to radicular dentin and root canal filling. MetaSEAL took the longest time to be removed and penetration into MetaSEAL was not possible without a solvent. Our findings confirms the pilot studies by Lawson et al22 who tested the solubility of set MetaSEAL in chloroform and suggested that the sealer was insoluble in chloroform after being polymerized for 1 week. The question of Roth 801's setting time has been identified by Nielson et al,23 who studied the setting time of Roth 801 in both aerobic and anaerobic conditions and reported that Roth 801 took more than 3 weeks to completely set. In addition, Allan et al24 concluded that Roth 801 was very slow setting, as none of their samples were completely set at 8 weeks. They speculated that sealers, particularly Roth 801, when tested under simulated clinical conditions set slowly and that setting is more delayed when tested “in vitro.” The conditions in which the “in vitro” samples are tested differ from clinical conditions (e.g., lack of a dentin wall, source of moisture, and appropriate environmental conditions, and placement within a compressed gutta-percha cone).23,24 Our results support both of these studies. In additional experiments, Roth 801 did not set after 6 weeks (data not shown). Our results show that the choice of root canal sealer is very important in the event of future root canal retreatment. The manufacturer of the Profile Universal Retreatment file recommends the files should be used in sequence starting with a D1 file with a cutting tip for the purpose of penetration into the root canal filling. We used only D3 files to focus on the chemical aspect of removing root filling, excluding the mechanical instrumentation. Giuliani et al25 observed better results for removing filling materials with the ProTaper Universal System for retreatment files in root canals filled with gutta-percha and sealer. To accomplish the goal of complete eradication of infection in a root canal, the effectiveness of sealer removal is a very important aspect for yielding superior clinical outcomes. CONCLUSION The study of Eikenberg, Keeler and Green26 on the dental encounters in Iraq between June 2009 and July 2010 showed 22.5% of dental emergency visits, pulpal disease requiring endodontic therapy accounted for 20.0%. Dental wellness of the soldiers is essential for effective combat strength. Dental emergencies take soldiers away from their assigned duties. Our study showed that use of the proper endodontic solvent makes complete removal of a sealer much more effective during retreatment and that complete removal of the sealer from the root canal is necessary for successful retreatment. Chloroform appears to be an universally used and cost effective solvent for gutta-percha during retreatment. It was significantly faster to remove AH-Plus with EndoSolv E than other solvents tested, and significantly faster than MetaSEAL regardless of the solvent, or no solvent. Solvents are required to remove MetaSEAL. The retreatment of root canal filling with AH Plus is more effective than MetaSEAL because AH Plus is soluble in a variety of solvents. EndoSolv E was more effective in removing a resin-based sealer, especially AH Plus, than EndoSolv R. REFERENCES 1. Rothfuss LG, Johnson SA, Larsen SD, Chaffin J, Finstuen K Staffing model for dental wellness and readiness. Mil Med  2004; 169: 604– 8. Google Scholar CrossRef Search ADS PubMed  2. Jones TK Army dental service support in a theater of operations. U.S. Army Med Dep J  2006; January–March: 5– 9. 3. Liewehr FR Endodontics and dental readiness. Mil Med  2000; 165: 127– 30. Google Scholar PubMed  4. Imura N, Pinheiro ET, Gomes BP, Zaia AA, Ferraz CC, Souza-Filho FJ The outcome of endodontic treatment: a retrospective study of 2000 cases performed by a specialist. J Endod  2007; 33( 11): 1278– 82. Google Scholar CrossRef Search ADS PubMed  5. Ricucci D, Langeland K Apical limit of root canal instrumentation and obturation, part 2. 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Google Scholar CrossRef Search ADS PubMed  25. Giuliani V, Cocchetti R, Pagavino G Efficacy of ProTaper Universal Retreatment files in removing filling materials during root canal retreatment. J Endod  2008; 34( 11): 1381– 4. Google Scholar CrossRef Search ADS PubMed  26. Eikenberg S, Keeler R, Green T Use of the Army Dental Command Corporate Dental Application as an electronic dental record in the Iraq theater of operations. US Army Med Dep J  2011; January–March: 51– 7. Footnotes 1 This study was presented at the Military Health System Research Symposium, Fort Lauderdale, Florida, August 12–15, 2013. 2 We affirm that we have no financial affiliation (e.g., employment, direct payment, stock holdings, retainers, consultantships, patent licensing arrangements or honoraria), or involvement with any commercial organization with direct financial interest in the subject or material discussed in this manuscript, nor have any such arrangements existed in the past 3 years. Any other potential conflict of interest is disclosed. Reprint & Copyright © Association of Military Surgeons of the U.S.
TI - The Effectiveness of Endodontic Solvents to Remove Endodontic Sealers
JO - Military Medicine
DO - 10.7205/MILMED-D-14-00379
DA - 2015-03-01
UR - https://www.deepdyve.com/lp/oxford-university-press/the-effectiveness-of-endodontic-solvents-to-remove-endodontic-sealers-gUrtAs2smj
SP - 92
EP - 95
VL - 180
IS - suppl_3
DP - DeepDyve
ER -