Regaining Apical Patency after Obturation with Gutta-percha and a Sealer Containing Mineral Trioxide Aggregate

Regaining Apical Patency after Obturation with Gutta-percha and a Sealer Containing Mineral Trioxide Aggregate

Basic Research—Technology Regaining Apical Patency after Obturation with Gutta-percha and a Sealer Containing Mineral Trioxide Aggregate Matthew T. C...

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Basic Research—Technology

Regaining Apical Patency after Obturation with Gutta-percha and a Sealer Containing Mineral Trioxide Aggregate Matthew T. Carpenter, DMD,* Stephanie J. Sidow, DDS,* Kimberly W. Lindsey, DDS,* Augustine Chuang, PhD,† and James C. McPherson, III, PhD† Abstract Introduction: MTA Fillapex (Angelus Solucoes Odontologicas, Londrina PR, Brazil) was introduced as a mineral trioxide aggregate (MTA)-based sealer used for endodontic obturation. There is a lack of research that evaluates the ability of different solvents to soften MTA-based sealers during retreatment. This study tested the ability of 4 commonly used endodontic solvents to soften gutta-percha and MTA Fillapex to allow for the re-establishment of apical patency. Methods: Eighty-six extracted maxillary anterior teeth were instrumented to the working length to a size 45 (.04 taper size). Teeth were divided into 2 groups (n = 43 for each group). MTA Fillapex was placed into all canals. Group 1 was obturated with gutta-percha to the working length, and group 2 was obturated 2 mm short of the working length to ensure the apical 2 mm was filled with sealer only. Both groups were divided into 4 subgroups (n = 10). The remaining teeth served as the control group. Each subgroup was exposed to 1 of the following solvents: chloroform, Endosolv R (Septodont, Saint-Maur, France), Endosolv E (Septodont), or eucalyptol. Results: Patency was re-established in 100% of the teeth in groups 1 and 2 when tested with chloroform or Endosolv E, 80% of the teeth in group 1 and 90% in group 2 when tested with eucalyptol, and 10% of the teeth in group 1 and 50% in group 2 tested when with Endosolv R. The chi-square test indicated there was a statistical difference between Endosolv R and the other tested solvents for both groups. Conclusions: Chloroform, Endosolv E, and Eucalyptol soften GP and MTA Fillapex sufficiently to aid in re-establishing apical patency during endodontic retreatment. (J Endod 2014;40:588–590)

Key Words Mineral trioxide aggregate, MTA Fillapex, patency, retreatment, sealer, solvent

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ndodontic retreatment is necessary when post-treatment disease is diagnosed (1). The objective of endodontic retreatment is to remove all of the obturation material, tissue debris, and other canal contents to create an environment conducive for healing. The removal of the obturation material and sealer can be challenging because these materials may occupy areas in which a file cannot make contact, such as in an isthmus, lateral canals, or dentinal tubules. The goal is to completely remove all of the canal contents, including the obturation core material and its associated sealer. This is accomplished by using a combination of chemical solvents and mechanical instrumentation (2). A body of research exists that compares different solvents and their effectiveness in softening root filling materials such as gutta-percha and endodontic sealers (3–8). Chloroform is a common solvent used in endodontic retreatment (9). It has proven itself over the years to be a safe (10) and effective solvent when used to soften or remove most endodontic obturation materials. Essential oils such as eucalyptol, turpentine, and orange oil have also shown the ability to aid in the removal of gutta-percha and various endodontic sealers during retreatment procedures (8). Endosolv E (Septodont, SaintMaur, France) is recommended for the removal of gutta-percha and zinc oxide– eugenol filling materials from the root canal (11). Endosolv R (Septodont) is formulated from formamide and phenyl-ethylic alcohol and is recommended for softening phenolic resin-type filling materials (12). Endodontic sealers or cements can be grouped based on their prime constituent or chemical structure, such as zinc oxide–eugenol, calcium hydroxide, glass ionomer, or resin. Recently, manufacturers have developed endodontic sealers that have added mineral trioxide aggregate (MTA) as an additional component. The current literature has shown that MTA-based sealers have similar sealing properties when compared with commonly used zinc oxide–eugenol sealers (13), release calcium ions on setting (14), and produce an inflammatory reaction similar to MTA when implanted in rat tissue (15, 16). However, the presence of MTA in a sealer may make the ability to revise the root canal difficult because of the cement-like hardness of set MTA (17). The ability to remove an MTA-based sealer from the inherent root canal irregularities and regain apical patency during retreatment may prove to be a significant challenge. If unable to completely remove the sealer from the root canal walls, the clinician may be faced with either potentially leaving infected material in the canal or enlarging the canal space with the intent of removing the sealer from the canal walls, ultimately weakening the root structure. MTA Fillapex (Angelus Solucoes Odontologicas, Londrina PR, Brazil) is 1 of several MTA-based sealers that has been recently introduced to the endodontic community. The manufacturer reports that the sealer is a 2-paste system that contains 40% MTA in the base paste. Preliminary research on MTA Fillapex shows that it has suitable physical properties necessary to be used as an endodontic sealer (18), possesses a

From the *US Army Dental Activity and †Department of Clinical Investigation, Fort Gordon, Augusta, Georgia. The opinions or assertions contained herein are the private views of the author and not to be construed as official or as reflecting the views of the U.S. Army Medical Department, Department of the Army, or the Department of Defense. Citation of commercial organizations and trade names in the manuscript do not constitute any official Department of the Army of Department of Defense endorsement or approval of the services of these organizations. Address requests for reprints to Dr Stephanie J. Sidow, US Army Dental Activity, Department of Endodontics, Fort Gordon, GA 30905. E-mail address: stephanie.j. [email protected] 0099-2399/$ - see front matter Copyright ª 2014 American Association of Endodontists. http://dx.doi.org/10.1016/j.joen.2013.10.020

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Basic Research—Technology high pH that contributes to its antibacterial activity (19), and possesses a bond strength to dentin similar to that of AH Plus (Dentsply, Konstanz, Germany) (20). Presently, no research exists that evaluates the effectiveness of different solvents to soften MTA-based sealers. This project is designed to test if commonly used endodontic solvents have the ability to soften MTA Fillapex to allow re-establishment of apical patency. The null hypothesis is that because of the presence of MTA in MTA Fillapex, patency will not be re-established with the use of endodontic solvents.

Materials and Methods Instrumentation and Obturation Eighty-six maxillary and mandibular single-rooted human anterior teeth were obtained for this study in accordance with the policies and procedures of the Dwight D. Eisenhower Army Medical Center’s Institutional Review Board, Fort Gordon, GA. Radiographs were taken to verify that each tooth had 1 canal and it was straight. The teeth were decoronated with a diamond-coated slow-speed band saw under water coolant. The canals were accessed, and the working length of each canal was determined by placing a #10 K-file so that the tip was visible at the apical foramen. Then, 1 mm was subtracted from the measured tooth length to gain the actual working length. A glide path of 20 (.02 taper size) was established, and the canals were instrumented using the crown-down technique with ProFile Vortex rotary files (Dentsply, Tulsa, OK) to a size of 45 (.04). After each file was used, the canal was irrigated with 6% NaOCl, and patency was reconfirmed. A 30-G side-vented needle was used with all irrigants to the working length. The final irrigation protocol for each canal was 3 mL 6% NaOCl followed by 3 mL 17% EDTA and a final irrigation of 3 mL 6% NaOCl to effectively remove the smear layer. The canals were dried with paper points, and patency was reconfirmed before obturation. The instrumented teeth were divided into 2 groups (n = 43 for each group). MTA Fillapex was introduced into the canal with a #25 Lentulo spiral to the working length until sealer was extruded from the apical foramen. In group 1, size 45 (.04) Vortex gutta-percha master cones were coated with sealer and placed to the working length. In group 2, size 45 (.04) Vortex gutta-percha master cones were trimmed to fit 2 mm short of the working length, coated with sealer, and inserted into the canal to simulate a ‘‘short obturation’’ and allow for the evaluation of regaining patency through mostly sealer. The System B Heat Source (SybronEndo, Orange, CA) was used in both test groups to remove the coronal gutta-percha, leaving a 3 mm apical plug. After compaction of the gutta-percha with Buchanan pluggers (SybronEndo), the canal was backfilled with gutta-percha using the Hot Shot Obturation Unit (Discus Dental, Culver City, CA). A dense, 3-dimensional obturation was confirmed with digital radiographs taken from both a mesial-distal and a buccal-lingual view. A cotton pellet was placed over the obturation, and the access was sealed with Fuji II LC (GC America, Alsip, IL). Specimens were stored at 37 C in 100% humidity for 2 weeks to ensure complete setting of the materials. TABLE 1. Group 1: Specimens That Were Filled with MTA Fillapex and Guttapercha to the Working Length Solvent

Number of specimens tested

Patency re-established

P value

Chloroform Endosolv E Endosolv R Eucalyptol No solvent

10 10 10 10 3

10 10 1 8 3

NA NA .001 .474 NA

NA, not applicable. Chi-square test. P value compared with chloroform.

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Removal of Obturation Material After 2 weeks, the restoration and cotton pellet were removed with a 557 bur in a high-speed handpiece. ProTaper Universal Retreatment files D1 and D2 (Dentsply) were used to remove the coronal guttapercha, leaving 3 mm of obturation material. The 2 treatment groups were divided into the following 5 subgroups based on the tested solvent: group A, chloroform (n = 10); group B, Endosolv R (n = 10); group C, Endosolv E (n = 10), group D, eucalyptol (n = 10), and group E, no solvent (n = 3). Group E served as the control group. In each subgroup, 2–3 drops of the test solvent were placed in the orifice adjacent to the remaining obturation material. An attempt was made to regain patency using a new #10 K-file. A #10 K-file was used because of its flexibility, which allowed for a better evaluation of the solvent’s ability to soften the obturation material rather than the file’s ability to penetrate the material. Patency was defined as visualization of the file from the anatomic apex. If patency was unable to be re-established within 3 minutes after placing the solvent, the test was terminated and recorded as a failure. All sample preparations, treatments, and evaluations were performed by a single operator. Statistical Analysis Statistical analyses were performed using SigmaPlot software (SigmaPlot, San Jose, CA). The Shapiro-Wilk test for normality failed for several groups. Thus, the nonparametric Kruskal-Wallis 1-way analysis of variance on ranks and the Dunnett post hoc test were chosen to test for for multiple comparisons of the experimental groups (ie, chloroform, Endosolv E, Endosolv R, and eucalyptol) versus the control group (no solvent). The Mann-Whitney U rank sum test was used to compare differences between the working length and the 2 mm short of the working length groups for each solvent. The Fisher exact test was used to determine significant differences between groups; the proportion of tests was successful (patency able to be regained) versus tests that were not successful (patency not able to be regained within 180 seconds). A power analysis indicated that 10 samples were required to reach a power of 0.80, and the null hypothesis that no statistical differences between the control and experimental groups existed was rejected at P # .05.

Results Group 1 Patency was re-established in all of the chloroform (10/10), Endosolv E (10/10), and control samples (3/3); in 8 of 10 for the Eucalyptol samples; and in 1 of 10 for the Endosolv R group. The chi-square test indicated that there was a statistical difference between the Endosolv R group and the other test groups (P = .001). Group 2 Patency was re-established in all of the chloroform and Endosolv E samples (10/10), in 9 of 10 of the Eucalyptol samples, and in 5 of 10 of the samples using Endosolv R. Patency was not re-established in any of the control samples (0/3). The chi-square test indicated that there was a statistical difference between the Endosolv R group and the other test groups (P = .033). There was a statistical difference between the Endosolv R group and all other test groups, which showed the inefficiency of Endosolv R in removing the MTA Fillapex sealer. The results are summarized in Tables 1 and 2.

Discussion Chloroform and Endosolv E consistently softened gutta-percha and MTA Fillapex obturations in order to allow proper removal and

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Basic Research—Technology TABLE 2. Group 2: Specimens That Were Filled with MTA Fillapex to the Working Length and Gutta-percha Trimmed 2 mm Short of the Working Length Solvent

Number of specimens tested

Patency re-established

P value

Chloroform Endosolv E Endosolv R Eucalyptol No solvent

10 10 10 10 3

10 10 5 9 0

NA NA .033 1.0 NA

NA, not applicable. Chi-square test. P value compared with chloroform.

re-establish patency. Eucalyptol was less effective in softening the obturation material, and Endosolv R failed to soften the obturation material sufficiently to allow for apical patency re-establishment. In an effort to reduce the effect that gutta-percha would have on the ability to regain patency and simulate a ‘‘short obturation,’’ group 2 master cones were seated 2 mm short of the working length. It is interesting to note that both Endosolv R and eucalyptol were more successful in re-establishing apical patency in group 2 than in group 1. This suggests that Endosolv R and eucalyptol are more effective at softening the MTA Fillapex than in softening the gutta-percha/sealer combination. Endosolv R is designed to be used with resin-based materials (11). The manufacturer of Endosolv R suggests removal of the obturation material with files before using the solvent to soften the remaining sealer. Because MTA Fillapex contains a resin matrix, perhaps this is the reason for the slight improvement in re-establishing patency. Group 1 had more gutta-percha (3 mm) to penetrate than group 2 (1 mm). Endosolv R was only able to aid in re-establishing patency in 1 of 10 teeth in group 1. The control group 1 results suggest that there are possible negative effects of Endosolv R on gutta-percha. When there was no solvent used in group 1, the K-file was able to penetrate the 3 mm of gutta-percha/sealer and regain patency. However, when Endosolv R was used in group 1, the K-file was not able to penetrate the 3 mm of gutta-percha/sealer and regain patency. Perhaps the Endosolv R alters the physical properties of the gutta-percha and therefore prevents softening. Patency was not regained in all 3 specimens in control group 2. This result indicates that the removal of MTA Fillapex may require additional methods. Chloroform and Endosolv E did allow for apical patency to be consistently re-established; therefore, the null hypothesis was rejected.

Conclusions Chloroform, Endosolv E, and Eucalyptol are commonly used endodontic solvents that successfully soften gutta-percha and MTA

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Fillapex sufficiently to allow for the re-establishment of patency. Endosolv R is not very successful in sufficiently softening gutta-percha and MTA Fillapex to re-gain patency.

Acknowledgments The authors deny any conflict of interest related to this study.

References 1. Mandel E, Friedman S. Endodontic retreatment: a rational approach to root canal reinstrumintation. J Endod 1992;18:565–9. 2. Friedman S, Stabholz A, Tamse A. Endodontic retreatment—case selection and technique. 3. Retreatment techniques. J Endod 1990;16:543–9. 3. Wilcox LR. Endodontic retreatment: ultrasonics and chloroform as the final step in reinstrumentation. J Endod 1989;15:125–8. 4. Martos J, Gastal MT, Sommer L, et al. Dissolving efficacy of organic solvents on root canal sealers. Clin Oral Investig 2006;10:50–4. 5. Whitworth JM, Boursin EM. Dissolution of root canal sealer cements in volatile solvents. Int Endod J 2000;33:19–24. 6. Kaplowitz GJ. Evaluation of gutta-percha solvents. J Endod 1990;16:539–40. 7. Wilcox LR, Krell KV, Madison S, et al. Endodontic retreatment: evaluation of guttapercha and sealer removal and canal reinstrumentation. J Endod 1987;13:453–7. 8. Tamse A, et al. Gutta-percha solvents—a comparative study. J Endod 1986;12: 337–9. 9. Vranas RN, Hartwell GR, Moon PC. The effect of endodontic solutions on resorcinolformalin paste. J Endod 2003;29:69–72. 10. McDonald MN, Vire DE. Chloroform in the endodontic operatory. J Endod 1992;18: 301–3. 11. Gambrel MG, Hartwell GR, Moon PC, et al. The effect of endodontic solutions on resorcinol-formalin paste in teeth. J Endod 2005;31:25–9. 12. Erdemir A, Adanir N, Belli S. In vitro evaluation of the dissolving effect of solvents on root canal sealers. J Oral Sci 2003;45:123–6. 13. Camilleri J, Gandolfi MG, Siboni F, et al. Dynamic sealing ability of MTA root canal sealer. Int Endod J 2011;44:9–20. 14. Massi S, Tanomaru-Filho M, Silva GF, et al. pH, calcium ion release, and setting time of an experimental mineral trioxide aggregate-based root canal sealer. J Endod 2011;37:844–6. 15. Scarparo RK, Haddad D, Acasigua GA, et al. Mineral trioxide aggregate-based sealer: analysis of tissue reactions to a new endodontic material. J Endod 2010;36:1174–8. 16. Gomes-Filho JE, Watanabe S, Bernabe PF, et al. A mineral trioxide aggregate sealer stimulated mineralization. J Endod 2009;35:256–60. 17. Parirokh M, Torabinejad M. Mineral trioxide aggregate: a comprehensive literature review–part I: chemical, physical, and antibacterial properties. J Endod 2010;36: 16–27. 18. Vitti RP, Prati C, Silva EJ, et al. Physical properties of MTA Fillapex Sealer. J Endod 2013;39:915–8. 19. Morgantal RD, Vier-Pelisser FV, Oliveira SD, et al. Antibacterial activity of two MTA-based root canal sealers. Int Endod J 2011;44:1128–33. 20. Assman E, Scarparo RK, Bottcher DE, et al. Dentin bond strength of two mineral trioxide aggregate–based and one epoxy resin–based sealers. J Endod 2012;38: 21921.

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