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Comparative Evaluation of the Efficiency of Manual and Rotary Gutta-percha Removal Techniques
Basic Research—Technology
Comparative Evaluation of the Efficiency of Manual and Rotary Gutta-percha Removal Techniques Ashwini S. Colaco, MDS,* and Vivekananda A.R. Pai, MDS† Abstract Introduction: This study aimed to evaluate the efficiency of 2 manual and 2 rotary gutta-percha (GP) removal techniques in terms of both the total operating time and GP remnants left in the canal. Methods: GP was removed with manual techniques using H-files and xylene (H + X) and H-files and System B (H + SB) (SybronEndo, Orange, CA) and with rotary techniques using the ProTaper Univeral Retreatment (PTUR) (Dentsply Maillefer, Ballaigues, Switzerland) and D-RaCe Retreatment (D-RR) (FKG Dentaire, La Chauxde-Fonds, Switzerland) systems. The total operating time was evaluated as the time taken to reach the working length and completely remove GP until no radiopaque remnants were observed in the final radiograph. Any GP remnants left in the canal were evaluated in terms of percentage in the whole canal. Results: Rotary techniques were significantly faster and left lesser GP remnants than manual techniques (P < .05). In rotary techniques, the D-RR system was significantly faster than the PTUR system (P < .05), but there was no significant difference between them regarding GP remnants (P > .05). In manual techniques, H + X was significantly faster and left lesser GP remnants than H + SB (P < .05). Conclusions: Rotary techniques were more efficient than manual techniques in GP removal. Overall, the D-RaCe Retreatment system was most efficient, whereas manual use of H-files with System B was least efficient. However, because all the techniques showed GP remnants in the canal and radiographs failed to show these remnants, additional measures would be required to ensure complete GP removal and check for cleaner canals during endodontic retreatment. (J Endod 2015;-:1–4)
A
manual technique with the combined use of H-files and a commonly used chemical solvent such as chloroform or xylene is suggested for the removal of a wellcompacted gutta-percha (GP) obturation during endodontic retreatment (1, 2). Similarly, another manual technique is suggested with the combined use of hand files and an electrically heated spreader or plugger such as System B Heat Source (SybronEndo, Orange, CA) (1). However, the removal of a well-compacted GP is tedious and time-consuming. Therefore, rotary files are recommended for saving time and reducing patient and operator fatigue (3, 4). Recently, the rotary nickel-titanium ProTaper Universal Retreatment (PTUR) (Dentsply Maillefer, Ballaigues, Switzerland) and D-RaCe Retreatment (D-RR) (FKG Dentaire, La Chaux-de-Fonds, Switzerland) systems have been specifically introduced for retreatment. The PTUR system consists of D1, D2, and D3 files, whereas the D-RR system is composed of DR1 and DR2 files. D1 and DR1 files have an active working tip to promote initial entry into the obturating material, and the rest of the files have a nonactive tip to reduce procedural errors during obturation removal (5, 6). Clinical efficiency of a GP removal technique depends on the total operating time, which is the time taken to reach the working length and, ideally, achieve complete removal of the obturation material (7). Many studies using various methods have evaluated and/or compared the effectiveness and/or the efficiency of various manual and rotary retreatment file techniques of GP removal. These studies have shown varying and/or contradictory results and, irrespective of the techniques used, have reported residual GP in the canal (4–18). However, only 2 studies have compared the rotary PTUR and D-RR systems. Although 1 study compared the effectiveness (4), the other study compared the efficiency (6) between these systems. However, these studies reported residual GP with both the systems but in a contradicting manner (4, 6). Otherwise, hardly any studies have evaluated and compared the efficiency in terms of the operating time and the effectiveness of the previously mentioned rotary systems and the aforementioned manual techniques. Radiographs are routinely used in a clinical practice to monitor GP removal and to verify the presence of root filling debris (19). Therefore, clinically it is more relevant to evaluate the efficiency of a GP removal technique in terms of the total operating time taken for the removal of GP until its radiopaque remnants are not seen in the radiograph and assessing any residual GP still left in the canal. In this context, the present study was conducted to evaluate and compare the efficiency of the aforementioned manual techniques and rotary retreatment systems in removing GP.
Key Words D-RaCe, gutta-percha removal, H-files, ProTaper, retreatment, System B, xylene
Materials and Methods Forty extracted intact single-rooted human teeth were decoronated to obtain a standardized root length of 15 mm. The working length was determined, and canal cleaning and shaping were done with ProTaper (Dentsply Maillefer) rotary files up
From the *Department of Conservative Dentistry and Endodontics, A.J. Institute of Dental Sciences, Kuntikan, Mangalore, Karnataka, India; and †Department of Conservative Dentistry and Endodontics, Faculty of Dentistry, Melaka Manipal Medical College (Manipal University), Bukit Baru, Melaka, Malaysia. Address requests for reprints to Dr Vivekananda A.R. Pai, Department of Conservative Dentistry and Endodontics, Faculty of Dentistry, Melaka Manipal Medical College (Manipal University), Jalan Batu Hampar, Bukit Baru, 75150 Melaka, Malaysia. E-mail address: [email protected] 0099-2399/$ - see front matter Copyright ª 2015 American Association of Endodontists. http://dx.doi.org/10.1016/j.joen.2015.07.012
JOE — Volume -, Number -, - 2015
Efficiency of Gutta-percha Removal Techniques
1
Basic Research—Technology to file size F2 using a crown-down technique. Canals were obturated with GP cones and zinc oxide–eugenol sealer (Endofill; Dentsply Ind e Com Ltda, Petropolis, RJ, Brazil) by using the lateral compaction technique. The obturated roots were randomly divided into 4 groups, with 10 roots (n = 10) each, for GP removal using H-files and xylene (H + X), H-files and System B (H + SB), the PTUR system, and the D-RR system, respectively. H + X and H + SB represented manual techniques, whereas the PTUR and D-RR systems represented rotary techniques for studying their efficiency in terms of the total operating time and any GP remnants left in the canal.
were analyzed using Image J 1.42a/Java 1.6.0-10 image analyzer software (National Institutes of Health, Bethesda, MD) to measure the area of GP remnants on the whole canal surface and the area of the canal walls. The percentage of GP remnants (A) was calculated using the following equation: A = (area of the remnants 100)/area of the root canal. The results were analyzed using the SPSS 15 software package (SPSS Inc, Chicago, IL) and applying 1-way analysis of variance and the Tukey post hoc test.
Evaluation of the Total Operating Time The total operating time was measured in seconds using an electric stopwatch. H + X Group. GP was softened incrementally by depositing 0.1 mL xylene (Merck Specialties, Mumbai, India). A size 20 H-file (Dentsply Maillefer) was used to penetrate and remove softened GP until the working length was reached. A size 30 H-file was used circumferentially to remove the remaining GP until its traces were not seen on the file. A radiograph was taken, and radiopaque remnants, if any, were removed by further instrumentation. The removal of GP was considered complete when no more remnants were detected in the final radiograph. The total operating time was calculated as the sum of the time taken for the initial removal of GP until the working length was reached and for the complete removal of GP excluding the time taken for the change of instruments, irrigation, and radiographs. H + SB Group. GP was softened using a Buchanan 0.06 taper plugger (SybronEndo) attached to the SB. The plugger was heated to 200 C and inserted into the obturation to a depth 3 mm short of the working length to transfer heat and soften GP. The plugger was kept for 15 seconds before removing. GP removal, radiographic monitoring, and the total operating time calculation were performed as described in the H + X group. PTUR System Group. The PTUR system was employed using D1 (size 30, .09 taper), D2 (size 25, .08 taper), and D3 (size 20, .07 taper) files sequentially to remove GP from the cervical, middle, and apical thirds, respectively, until the working length was reached. These files were used with an X Smart electric motor (Dentsply Maillefer) in a brushing motion at the manufacturer’s recommended speed (300 rpm) and torque (2 N/cm). GP removal was considered complete when no more radiopaque remnants were detected in the radiograph. The total operating time was calculated as the sum of the time taken by D1, D2, and D3 files excluding the time taken for the change of files, irrigation, and radiographs. D-RR System Group. The D-RR system was employed using DR1 (size 30, .10 taper) and DR2 (size 25, .04 taper) files to remove GP from the coronal and apical half areas, respectively, until the working length was reached. These files were used with an X Smart electric motor (Dentsply Maillefer) at the manufacturer’s recommended speed and torque. The DR1 file was used at a speed of 1000 rpm and a torque of 1.5 N/cm, whereas the DR2 file was used at a speed of 600 rpm and a torque of 0.7 N/cm. The verification of complete GP removal and the total operating time calculation were done as in the PTUR system group. However, the total operating time was considered as the sum of the time taken by the DR1 and DR2 files.
The mean total operating time and the percentage of GP remnants with a significant difference (P < .05) among the study groups are shown in Table 1. Rotary techniques (PTUR and D-RR systems) were significantly faster and left lesser GP remnants than manual techniques (H + X and H + SB) (P < .05, Tables 2 and 3). There were also significant differences (P < .05) between the groups in rotary and manual techniques. In manual techniques, H + X was significantly faster and left lesser GP remnants than H + SB (P < .05, Tables 2 and 3). However, in rotary techniques, the D-RR system was significantly faster than the PTUR system (P < .05, Table 2), but there was no significant difference between them regarding GP remnants (P > .05, Table 3). Overall, the D-RR system was most effective because it was the fastest with the least amount of GP remnants, and its differences with all the remaining groups were significant (P < .05) except with the PTUR system regarding GP remnants (P > .05). On the contrary, H + SB was the least effective because it was the slowest with the most GP remnants and had significant differences (P < .05) with all the remaining groups (Tables 2 and 3).
Evaluation of GP Remnants The roots were grooved longitudinally in a buccolingual direction with a diamond disk and split into 2 halves with a chisel. The canal walls of the sectioned roots were imaged using a compound microscope of magnification 40 (Olympus cx21; Olympus, Melville, NY). The images 2
Colaco and Pai
Results
Discussion In the present study, rotary techniques were significantly faster than manual techniques. This is in agreement with most related studies although a few studies have reported the contrary. Rotary techniques are faster because of the motion, inherent speed, greater taper, flute design, and active tip of the rotary files. Rotary files in motion generate frictional heat, which plasticizes and softens GP (6, 7, 20–22). Their active working tip facilitates the initial penetration of GP and penetration of the subsequent files. Their flutes allow coronal extrusion of GP in spirals around the files to remove GP faster (1, 4–11). In our study, both the manual and rotary techniques had GP remnants in the canal despite the removal of GP until no more radiopaque traces were detected in the radiograph. This indicates the limitation of the radiographs in verifying the complete removal of the obturation from the canal. Radiographs are a 2-dimensional image of a 3-dimensional structure and prone to magnification and distortion. They are less TABLE 1. Total Operating Time (in seconds) for Complete GP Removal and GP Remnants (in percentage) Seen in the Whole Canal Number of samples (n) Groups H+X H + SB PTUR D-RR
10 10 10 10
Mean total operating time ± SD (in seconds) 219.80 29.68 451.20 7.82 111.70 3.56 70.70 2.83
Mean GP remnants ± SD P (in percentage) Value 45.58 13.39 60.47 12.38 30.23 11.29 29.57 6.43
<.001
D-RR, DRaCe Retreatment; GP, gutta-percha; H + SB, H-files and System B; H + X, H-files and xylene; PTUR, ProTaper Universal Retreatment; SD, standard deviation. P < .05 is statistically significant.
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Basic Research—Technology TABLE 2. Intergroup Comparison of the Total Operating Time (in seconds)
Group
Group
H+X
H + SB PTUR D-RR PTUR D-RR D-RR
H + SB PTUR
Difference in mean total operating time (in seconds) 231.40 108.10 149.10 339.50 380.50 41.00
SE
P Value
6.94 6.94 6.94 6.94 6.94 6.94
<.001 <.001 <.001 <.001 <.001 <.001
D-RR, DRaCe Retreatment; GP, gutta-percha; H + SB, H-files and System B; H + X, H-files and xylene; PTUR, ProTaper Universal Retreatment; SE, standard error. P value <.05 is statistically significant.
accurate in detecting obturation debris and may fail to reveal all remaining remnants, particularly small ones. Radiographs may also not detect a thin layer of GP remnants having radiopacity similar to dentin (11, 19, 23, 24). The fact that GP remnants were seen with both the manual and rotary techniques in our study is in accordance with previous studies. However, these studies have found contradictory results regarding the comparison of residual GP between the manual and rotary techniques (1, 4–15, 22, 24–28). In our study, rotary techniques had significantly less GP remnants than manual techniques, and this could be attributed to the design of the D-RR and PTUR files. D-RR files display alternating cutting edges with a triangular cross section and a smooth surface because of a special electrochemical surface treatment. This file design provides superior sharpness and cleaning ability for the efficient removal and coronal extrusion of GP from the canal (4, 6). PTUR files have a larger internal mass and area, a convex triangular cross section, a variable taper, and a continuously changing helical pitch. Again, this design leads to effective cutting and coronal extrusion of GP from the canal (4, 7, 10, 27). Compared with rotary techniques, manual techniques H + X and H + SB were found less efficient in our study. This is an important finding because hardly any studies have compared these manual techniques with the rotary techniques evaluated in our study. Moreover, few studies that could be quoted in this regard had different study designs and/or methodologies (10, 26, 29). The lesser efficiency of H + X and H + SB, despite the effectiveness of H-files in engaging GP, could be caused by the use of a solvent and heat with these techniques, respectively. The use of a solvent or heat causes smearing or adherence of a fine filmy layer of GP to the canal walls. This film of GP is difficult to detect and remove, resulting in increased retreatment time and residual GP (1, 3, 26, 30, 31). Regarding the total operating time of rotary techniques, our study found that the D-RR system was significantly faster than the PTUR TABLE 3. Intergroup Comparison of the GP Remnants (in percentage) Group
Group
H+X
H + SB PTUR D-RR PTUR D-RR D-RR
H + SB PTUR
Difference in mean GP remnants (in percentage) 14.89 15.35 16.01 30.24 30.90 0.66
SE
P Value
2.89 2.89 2.89 2.89 2.89 2.89
<.001 <.001 <.001 <.001 <.001 .996
D-RR, DRaCe Retreatment; GP, gutta-percha; H + SB, H-files and System B; H + X, H-files and xylene; PTUR, ProTaper Universal Retreatment; SE, standard error. P value <.05 is statistically significant.
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system. A previous study by Rodig et al (6) compared the operating time of these systems. Our finding is in agreement with that study but difficult to justify because both the systems are rotary in nature. However, it could probably be attributed to the differences in the file design, number of files used, and operational speed as recommended by the manufacturer (16). The D-RR system uses only 2 files and at a relatively higher speed compared with 3 files used at a lower speed in the PTUR system. The difference in the tip size of the last file used may also play a role in this finding (12). Regarding GP remnants seen with rotary techniques, our study found no significant difference between the D-RR and PTUR systems. Previously, 2 studies reported a significant difference in GP remnants between these systems. These studies reported in a contradicting manner; however, they both attributed the findings to the aforementioned unique design of the files used with these systems (4, 6). In our study, the D-RR system showed slightly less GP remnants than the PTUR system. Apart from the file design, this finding could probably be caused by the size of the last file used. When a last used file is smaller than the apical canal diameter, it may not engage the canal walls and complete the cleaning action (4–6, 8, 14). The last file in the D-RR system (DR2 file, size 25) is larger than the one in the PTUR system (D3 file, size 20) and might contribute to better canal cleaning (4, 6). Regarding manual techniques, our study found that H + SB was significantly less efficient than H + X. Although this is an important finding, discussion in this regard is limited because studies comparing these techniques are lacking. Although SB was shown to be more effective than a solvent for the removal of GP in 1 study, the use of H + SB was found to be least effective in another study (26, 29). However, these studies could be compared neither with each other nor with our study because of the differences in the study design. Nevertheless, the lesser efficiency of H + SB compared with H + X could be caused by the limited heat conductivity of GP and the adherence of softened GP to the canal walls, which is difficult to clean with a file. Although the latter may also occur with xylene, GP softening with xylene is more effective for the penetration and removal with H-files than heat because GP is a poor conductor of heat (1, 3, 26, 30).
Conclusion Rotary retreatment techniques were more efficient than manual techniques in GP removal. Among these techniques, the rotary D-RaCe Retreatment system was most efficient, whereas the manual use of H-files with System B was least efficient. However, because all the techniques showed GP remnants on the canal walls, additional measures such as the combination of rotary and manual techniques and further instrumentation than the recommended would be beneficial to completely remove GP during endodontic retreatment. Moreover, because radiographs failed to show these GP remnants, further measures such as the use of dental operating microscopes and fiberoptic endoscopes would be more advisable to check the adequacy of complete GP removal.
Acknowledgments The authors deny any conflicts of interest related to this study.
References 1. Duncan HF, Chong BF. Removal of root filling materials. Endod Topics 2011;19: 33–57. 2. Magalh~aes BS, Johann JE, Lund RG, et al. Dissolving efficacy of some organic solvents on gutta-percha. Braz Oral Res 2007;21:303–7.
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Basic Research—Technology 3. H€ulsmann M, Stotz S. Efficacy, cleaning ability and safety of different devices for gutta-percha removal in root canal retreatment. Int Endod J 1997;30:227–33. 4. Marques da Silva B, Baratto-Filho F, Leonardi DP, et al. Effectiveness of ProTaper, D-RaCe, and Mtwo retreatment files with and without supplementary instruments in the removal of root canal filling material. Int Endod J 2012;45: 927–32. 5. Marfisi K, Mercade M, Plotino G, et al. Efficacy of three different rotary files to remove gutta-percha and Resilon from root canals. Int Endod J 2010;43:1022–8. 6. Rodig T, Hausdorfer T, Konietschke F, et al. Efficacy of D-RaCe and ProTaper Universal Retreatment NiTi instruments and hand files in removing gutta-percha from curved root canals—a micro-computed tomography study. Int Endod J 2012;45:580–9. 7. Gu LS, Ling JQ, Wei X, Huang XY. Efficacy of ProTaper Universal rotary retreatment system for gutta-percha removal from root canals. Int Endod J 2008;41: 288–95. 8. Giuliani V, Cocchetti R, Pagavino G. Efficacy of ProTaper universal retreatment files in removing filling materials during root canal retreatment. J Endod 2008;34: 1381–4. 9. Takahashi CM, Cunha RS, de Martin AS, et al. In vitro evaluation of the effectiveness of ProTaper universal rotary retreatment system for gutta-percha removal with or without a solvent. J Endod 2009;35:1580–3. 10. Bramante CM, Fidelis NS, Assumpcao TS, et al. Heat release, time required, and cleaning ability of MTwo R and ProTaper universal retreatment systems in the removal of filling material. J Endod 2010;36:1870–3. 11. Unal GC, Kaya BU, Tac AG, Kececi AD. A comparison of the efficacy of conventional and new retreatment instruments to remove gutta-percha in curved root canals:an ex vivo study. Int Endod J 2009;42:344–50. 12. Ring J, Murray PE, Namerow KN, et al. Removing root canal obturation materials: a comparison of rotary file systems and re-treatment agents. J Am Dent Assoc 2009; 140:680–8. 13. Somma F, Cammarota G, Plotino G, et al. The effectiveness of manual and mechanical instrumentation for the retreatment of three different root canal filling materials. J Endod 2008;34:466–9. 14. Hammad M, Qualtrough A, Silikas N. Three-dimensional evaluation of effectiveness of hand and rotary instrumentation for retreatment of canals filled with different materials. J Endod 2008;34:1370–3. 15. So MV, Saran C, Magro ML, et al. Efficacy of ProTaper retreatment system in root canals filled with gutta-percha and two endodontic sealers. J Endod 2008;34: 1223–5.
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16. Hayakawa T, Tomita F, Okiji T. Influence of the diameter and taper of root canals on the removal efficiency of Thermafil Plus plastic carriers using ProTaper retreatment files. J Endod 2010;36:1676–8. 17. Tasdemir T, Yildirim T, Celik D. Comparative study of removal of current endodontic fillings. J Endod 2008;34:326–9. 18. Tasdemir T, Er K, Yildirim T, Celik D. Efficacy of three rotary NiTi instruments in removing gutta-percha from root canals. Int Endod J 2008;41:191–6. 19. de Carvalho Maciel AC, Zaccaro Scelza MF. Efficacy of automated versus hand instrumentation during root canal retreatment: an ex vivo study. Int Endod J 2006;39: 779–84. 20. Bramante CM, Betti LV. Efficacy of Quantec rotary instruments for gutta-percha removal. Int Endod J 2000;33:463–7. 21. Betti LV, Bramante CM. Quantec SC rotary instruments versus hand files for guttapercha removal in root canal retreatment. Int Endod J 2001;34:514–9. 22. Hulsmann M, Bluhm V. Efficacy, cleaning ability and safety of different rotary NiTi instruments in root canal retreatment. Int Endod J 2004;37:468–76. 23. Schirrmeister JF, Hermanns P, Meyer KM, et al. Detectability of residual Epiphany and gutta-percha after root canal retreatment using a dental operating microscope and radiographs–an ex vivo study. Int Endod J 2006;39:558–65. 24. Imura N, Kato AS, Hata GI, et al. A comparison of the relative efficacies of four hand and rotary instrumentation techniques during endodontic retreatment. Int Endod J 2000;33:361–6. 25. Saad AY, Al-Hadlaq SM, Al-Katheeri NH. Efficacy of two rotary NiTi instruments in the removal of gutta-percha during root canal retreatment. J Endod 2007;33: 38–41. 26. Bodrumlu E, Uzun O, Topuz O, Semiz M. Efficacy of 3 techniques in removing root canal filling material. J Can Dent Assoc 2008;74:721. 27. Schirrmeister JF, Wrbas KT, Meyer KM, et al. Efficacy of different rotary instruments for gutta-percha removal in root canal retreatment. J Endod 2006;32:469–72. 28. Schirrmeister JF, Wrbas KT, Schneider FH, et al. Effectiveness of a hand file and three nickel-titanium rotary instruments for removing gutta-percha in curved root canals during retreatment. Oral Surg Oral Med Oral Pathol Oral Radiol Endod 2006;101: 542–7. 29. Wolcott JF, Himel VT, Hicks ML. Thermafil retreatment using a new ‘‘System B’’ technique or a solvent. J Endod 1999;25:761–4. 30. Sae-Lim V, Rajamanickam I, Lim BK, Lee HL. Effectiveness of ProFile .04 taper rotary instruments in endodontic retreatment. J Endod 2000;26:100–4. 31. Wilcox LR, Juhlin JJ. Endodontic retreatment of Thermafil versus laterally condensed gutta-percha. J Endod 1994;20:115–7.
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Comparative Evaluation of the Efficiency of Manual and Rotary Gutta-percha Removal Techniques Ashwini S. Colaco, MDS,* and Vivekananda A.R. Pai, MDS† Abstract Introduction: This study aimed to evaluate the efficiency of 2 manual and 2 rotary gutta-percha (GP) removal techniques in terms of both the total operating time and GP remnants left in the canal. Methods: GP was removed with manual techniques using H-files and xylene (H + X) and H-files and System B (H + SB) (SybronEndo, Orange, CA) and with rotary techniques using the ProTaper Univeral Retreatment (PTUR) (Dentsply Maillefer, Ballaigues, Switzerland) and D-RaCe Retreatment (D-RR) (FKG Dentaire, La Chauxde-Fonds, Switzerland) systems. The total operating time was evaluated as the time taken to reach the working length and completely remove GP until no radiopaque remnants were observed in the final radiograph. Any GP remnants left in the canal were evaluated in terms of percentage in the whole canal. Results: Rotary techniques were significantly faster and left lesser GP remnants than manual techniques (P < .05). In rotary techniques, the D-RR system was significantly faster than the PTUR system (P < .05), but there was no significant difference between them regarding GP remnants (P > .05). In manual techniques, H + X was significantly faster and left lesser GP remnants than H + SB (P < .05). Conclusions: Rotary techniques were more efficient than manual techniques in GP removal. Overall, the D-RaCe Retreatment system was most efficient, whereas manual use of H-files with System B was least efficient. However, because all the techniques showed GP remnants in the canal and radiographs failed to show these remnants, additional measures would be required to ensure complete GP removal and check for cleaner canals during endodontic retreatment. (J Endod 2015;-:1–4)
A
manual technique with the combined use of H-files and a commonly used chemical solvent such as chloroform or xylene is suggested for the removal of a wellcompacted gutta-percha (GP) obturation during endodontic retreatment (1, 2). Similarly, another manual technique is suggested with the combined use of hand files and an electrically heated spreader or plugger such as System B Heat Source (SybronEndo, Orange, CA) (1). However, the removal of a well-compacted GP is tedious and time-consuming. Therefore, rotary files are recommended for saving time and reducing patient and operator fatigue (3, 4). Recently, the rotary nickel-titanium ProTaper Universal Retreatment (PTUR) (Dentsply Maillefer, Ballaigues, Switzerland) and D-RaCe Retreatment (D-RR) (FKG Dentaire, La Chaux-de-Fonds, Switzerland) systems have been specifically introduced for retreatment. The PTUR system consists of D1, D2, and D3 files, whereas the D-RR system is composed of DR1 and DR2 files. D1 and DR1 files have an active working tip to promote initial entry into the obturating material, and the rest of the files have a nonactive tip to reduce procedural errors during obturation removal (5, 6). Clinical efficiency of a GP removal technique depends on the total operating time, which is the time taken to reach the working length and, ideally, achieve complete removal of the obturation material (7). Many studies using various methods have evaluated and/or compared the effectiveness and/or the efficiency of various manual and rotary retreatment file techniques of GP removal. These studies have shown varying and/or contradictory results and, irrespective of the techniques used, have reported residual GP in the canal (4–18). However, only 2 studies have compared the rotary PTUR and D-RR systems. Although 1 study compared the effectiveness (4), the other study compared the efficiency (6) between these systems. However, these studies reported residual GP with both the systems but in a contradicting manner (4, 6). Otherwise, hardly any studies have evaluated and compared the efficiency in terms of the operating time and the effectiveness of the previously mentioned rotary systems and the aforementioned manual techniques. Radiographs are routinely used in a clinical practice to monitor GP removal and to verify the presence of root filling debris (19). Therefore, clinically it is more relevant to evaluate the efficiency of a GP removal technique in terms of the total operating time taken for the removal of GP until its radiopaque remnants are not seen in the radiograph and assessing any residual GP still left in the canal. In this context, the present study was conducted to evaluate and compare the efficiency of the aforementioned manual techniques and rotary retreatment systems in removing GP.
Key Words D-RaCe, gutta-percha removal, H-files, ProTaper, retreatment, System B, xylene
Materials and Methods Forty extracted intact single-rooted human teeth were decoronated to obtain a standardized root length of 15 mm. The working length was determined, and canal cleaning and shaping were done with ProTaper (Dentsply Maillefer) rotary files up
From the *Department of Conservative Dentistry and Endodontics, A.J. Institute of Dental Sciences, Kuntikan, Mangalore, Karnataka, India; and †Department of Conservative Dentistry and Endodontics, Faculty of Dentistry, Melaka Manipal Medical College (Manipal University), Bukit Baru, Melaka, Malaysia. Address requests for reprints to Dr Vivekananda A.R. Pai, Department of Conservative Dentistry and Endodontics, Faculty of Dentistry, Melaka Manipal Medical College (Manipal University), Jalan Batu Hampar, Bukit Baru, 75150 Melaka, Malaysia. E-mail address: [email protected] 0099-2399/$ - see front matter Copyright ª 2015 American Association of Endodontists. http://dx.doi.org/10.1016/j.joen.2015.07.012
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Basic Research—Technology to file size F2 using a crown-down technique. Canals were obturated with GP cones and zinc oxide–eugenol sealer (Endofill; Dentsply Ind e Com Ltda, Petropolis, RJ, Brazil) by using the lateral compaction technique. The obturated roots were randomly divided into 4 groups, with 10 roots (n = 10) each, for GP removal using H-files and xylene (H + X), H-files and System B (H + SB), the PTUR system, and the D-RR system, respectively. H + X and H + SB represented manual techniques, whereas the PTUR and D-RR systems represented rotary techniques for studying their efficiency in terms of the total operating time and any GP remnants left in the canal.
were analyzed using Image J 1.42a/Java 1.6.0-10 image analyzer software (National Institutes of Health, Bethesda, MD) to measure the area of GP remnants on the whole canal surface and the area of the canal walls. The percentage of GP remnants (A) was calculated using the following equation: A = (area of the remnants 100)/area of the root canal. The results were analyzed using the SPSS 15 software package (SPSS Inc, Chicago, IL) and applying 1-way analysis of variance and the Tukey post hoc test.
Evaluation of the Total Operating Time The total operating time was measured in seconds using an electric stopwatch. H + X Group. GP was softened incrementally by depositing 0.1 mL xylene (Merck Specialties, Mumbai, India). A size 20 H-file (Dentsply Maillefer) was used to penetrate and remove softened GP until the working length was reached. A size 30 H-file was used circumferentially to remove the remaining GP until its traces were not seen on the file. A radiograph was taken, and radiopaque remnants, if any, were removed by further instrumentation. The removal of GP was considered complete when no more remnants were detected in the final radiograph. The total operating time was calculated as the sum of the time taken for the initial removal of GP until the working length was reached and for the complete removal of GP excluding the time taken for the change of instruments, irrigation, and radiographs. H + SB Group. GP was softened using a Buchanan 0.06 taper plugger (SybronEndo) attached to the SB. The plugger was heated to 200 C and inserted into the obturation to a depth 3 mm short of the working length to transfer heat and soften GP. The plugger was kept for 15 seconds before removing. GP removal, radiographic monitoring, and the total operating time calculation were performed as described in the H + X group. PTUR System Group. The PTUR system was employed using D1 (size 30, .09 taper), D2 (size 25, .08 taper), and D3 (size 20, .07 taper) files sequentially to remove GP from the cervical, middle, and apical thirds, respectively, until the working length was reached. These files were used with an X Smart electric motor (Dentsply Maillefer) in a brushing motion at the manufacturer’s recommended speed (300 rpm) and torque (2 N/cm). GP removal was considered complete when no more radiopaque remnants were detected in the radiograph. The total operating time was calculated as the sum of the time taken by D1, D2, and D3 files excluding the time taken for the change of files, irrigation, and radiographs. D-RR System Group. The D-RR system was employed using DR1 (size 30, .10 taper) and DR2 (size 25, .04 taper) files to remove GP from the coronal and apical half areas, respectively, until the working length was reached. These files were used with an X Smart electric motor (Dentsply Maillefer) at the manufacturer’s recommended speed and torque. The DR1 file was used at a speed of 1000 rpm and a torque of 1.5 N/cm, whereas the DR2 file was used at a speed of 600 rpm and a torque of 0.7 N/cm. The verification of complete GP removal and the total operating time calculation were done as in the PTUR system group. However, the total operating time was considered as the sum of the time taken by the DR1 and DR2 files.
The mean total operating time and the percentage of GP remnants with a significant difference (P < .05) among the study groups are shown in Table 1. Rotary techniques (PTUR and D-RR systems) were significantly faster and left lesser GP remnants than manual techniques (H + X and H + SB) (P < .05, Tables 2 and 3). There were also significant differences (P < .05) between the groups in rotary and manual techniques. In manual techniques, H + X was significantly faster and left lesser GP remnants than H + SB (P < .05, Tables 2 and 3). However, in rotary techniques, the D-RR system was significantly faster than the PTUR system (P < .05, Table 2), but there was no significant difference between them regarding GP remnants (P > .05, Table 3). Overall, the D-RR system was most effective because it was the fastest with the least amount of GP remnants, and its differences with all the remaining groups were significant (P < .05) except with the PTUR system regarding GP remnants (P > .05). On the contrary, H + SB was the least effective because it was the slowest with the most GP remnants and had significant differences (P < .05) with all the remaining groups (Tables 2 and 3).
Evaluation of GP Remnants The roots were grooved longitudinally in a buccolingual direction with a diamond disk and split into 2 halves with a chisel. The canal walls of the sectioned roots were imaged using a compound microscope of magnification 40 (Olympus cx21; Olympus, Melville, NY). The images 2
Colaco and Pai
Results
Discussion In the present study, rotary techniques were significantly faster than manual techniques. This is in agreement with most related studies although a few studies have reported the contrary. Rotary techniques are faster because of the motion, inherent speed, greater taper, flute design, and active tip of the rotary files. Rotary files in motion generate frictional heat, which plasticizes and softens GP (6, 7, 20–22). Their active working tip facilitates the initial penetration of GP and penetration of the subsequent files. Their flutes allow coronal extrusion of GP in spirals around the files to remove GP faster (1, 4–11). In our study, both the manual and rotary techniques had GP remnants in the canal despite the removal of GP until no more radiopaque traces were detected in the radiograph. This indicates the limitation of the radiographs in verifying the complete removal of the obturation from the canal. Radiographs are a 2-dimensional image of a 3-dimensional structure and prone to magnification and distortion. They are less TABLE 1. Total Operating Time (in seconds) for Complete GP Removal and GP Remnants (in percentage) Seen in the Whole Canal Number of samples (n) Groups H+X H + SB PTUR D-RR
10 10 10 10
Mean total operating time ± SD (in seconds) 219.80 29.68 451.20 7.82 111.70 3.56 70.70 2.83
Mean GP remnants ± SD P (in percentage) Value 45.58 13.39 60.47 12.38 30.23 11.29 29.57 6.43
<.001
D-RR, DRaCe Retreatment; GP, gutta-percha; H + SB, H-files and System B; H + X, H-files and xylene; PTUR, ProTaper Universal Retreatment; SD, standard deviation. P < .05 is statistically significant.
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Basic Research—Technology TABLE 2. Intergroup Comparison of the Total Operating Time (in seconds)
Group
Group
H+X
H + SB PTUR D-RR PTUR D-RR D-RR
H + SB PTUR
Difference in mean total operating time (in seconds) 231.40 108.10 149.10 339.50 380.50 41.00
SE
P Value
6.94 6.94 6.94 6.94 6.94 6.94
<.001 <.001 <.001 <.001 <.001 <.001
D-RR, DRaCe Retreatment; GP, gutta-percha; H + SB, H-files and System B; H + X, H-files and xylene; PTUR, ProTaper Universal Retreatment; SE, standard error. P value <.05 is statistically significant.
accurate in detecting obturation debris and may fail to reveal all remaining remnants, particularly small ones. Radiographs may also not detect a thin layer of GP remnants having radiopacity similar to dentin (11, 19, 23, 24). The fact that GP remnants were seen with both the manual and rotary techniques in our study is in accordance with previous studies. However, these studies have found contradictory results regarding the comparison of residual GP between the manual and rotary techniques (1, 4–15, 22, 24–28). In our study, rotary techniques had significantly less GP remnants than manual techniques, and this could be attributed to the design of the D-RR and PTUR files. D-RR files display alternating cutting edges with a triangular cross section and a smooth surface because of a special electrochemical surface treatment. This file design provides superior sharpness and cleaning ability for the efficient removal and coronal extrusion of GP from the canal (4, 6). PTUR files have a larger internal mass and area, a convex triangular cross section, a variable taper, and a continuously changing helical pitch. Again, this design leads to effective cutting and coronal extrusion of GP from the canal (4, 7, 10, 27). Compared with rotary techniques, manual techniques H + X and H + SB were found less efficient in our study. This is an important finding because hardly any studies have compared these manual techniques with the rotary techniques evaluated in our study. Moreover, few studies that could be quoted in this regard had different study designs and/or methodologies (10, 26, 29). The lesser efficiency of H + X and H + SB, despite the effectiveness of H-files in engaging GP, could be caused by the use of a solvent and heat with these techniques, respectively. The use of a solvent or heat causes smearing or adherence of a fine filmy layer of GP to the canal walls. This film of GP is difficult to detect and remove, resulting in increased retreatment time and residual GP (1, 3, 26, 30, 31). Regarding the total operating time of rotary techniques, our study found that the D-RR system was significantly faster than the PTUR TABLE 3. Intergroup Comparison of the GP Remnants (in percentage) Group
Group
H+X
H + SB PTUR D-RR PTUR D-RR D-RR
H + SB PTUR
Difference in mean GP remnants (in percentage) 14.89 15.35 16.01 30.24 30.90 0.66
SE
P Value
2.89 2.89 2.89 2.89 2.89 2.89
<.001 <.001 <.001 <.001 <.001 .996
D-RR, DRaCe Retreatment; GP, gutta-percha; H + SB, H-files and System B; H + X, H-files and xylene; PTUR, ProTaper Universal Retreatment; SE, standard error. P value <.05 is statistically significant.
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system. A previous study by Rodig et al (6) compared the operating time of these systems. Our finding is in agreement with that study but difficult to justify because both the systems are rotary in nature. However, it could probably be attributed to the differences in the file design, number of files used, and operational speed as recommended by the manufacturer (16). The D-RR system uses only 2 files and at a relatively higher speed compared with 3 files used at a lower speed in the PTUR system. The difference in the tip size of the last file used may also play a role in this finding (12). Regarding GP remnants seen with rotary techniques, our study found no significant difference between the D-RR and PTUR systems. Previously, 2 studies reported a significant difference in GP remnants between these systems. These studies reported in a contradicting manner; however, they both attributed the findings to the aforementioned unique design of the files used with these systems (4, 6). In our study, the D-RR system showed slightly less GP remnants than the PTUR system. Apart from the file design, this finding could probably be caused by the size of the last file used. When a last used file is smaller than the apical canal diameter, it may not engage the canal walls and complete the cleaning action (4–6, 8, 14). The last file in the D-RR system (DR2 file, size 25) is larger than the one in the PTUR system (D3 file, size 20) and might contribute to better canal cleaning (4, 6). Regarding manual techniques, our study found that H + SB was significantly less efficient than H + X. Although this is an important finding, discussion in this regard is limited because studies comparing these techniques are lacking. Although SB was shown to be more effective than a solvent for the removal of GP in 1 study, the use of H + SB was found to be least effective in another study (26, 29). However, these studies could be compared neither with each other nor with our study because of the differences in the study design. Nevertheless, the lesser efficiency of H + SB compared with H + X could be caused by the limited heat conductivity of GP and the adherence of softened GP to the canal walls, which is difficult to clean with a file. Although the latter may also occur with xylene, GP softening with xylene is more effective for the penetration and removal with H-files than heat because GP is a poor conductor of heat (1, 3, 26, 30).
Conclusion Rotary retreatment techniques were more efficient than manual techniques in GP removal. Among these techniques, the rotary D-RaCe Retreatment system was most efficient, whereas the manual use of H-files with System B was least efficient. However, because all the techniques showed GP remnants on the canal walls, additional measures such as the combination of rotary and manual techniques and further instrumentation than the recommended would be beneficial to completely remove GP during endodontic retreatment. Moreover, because radiographs failed to show these GP remnants, further measures such as the use of dental operating microscopes and fiberoptic endoscopes would be more advisable to check the adequacy of complete GP removal.
Acknowledgments The authors deny any conflicts of interest related to this study.
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