- Email: [email protected]
Efficacy of Profile .04 taper series 29 in removing filling materials during root canal retreatment—an in vitro study
Efficacy of Profile .04 taper series 29 in removing filling materials during root canal retreatment—an in vitro study Luciana Viti Betti, DDS, PhD,a Clovis Monteiro Bramante, DDS, PhD,b Ivaldo Gomes de Moraes, DDS, PhD,b Norberti Bernardineli, DDS, PhD,b and Roberto Brandão Garcia, DDS, PhD,b São Paulo, Brazil UNIVERSITY OF SÃO PAULO
Objective. The aim of this study was to compare Profile .04 taper series 29 instruments and hand files for gutta-percha removal. Study design. Twenty maxillary central incisors with a single straight canal were instrumented and filled. The teeth were divided into 2 groups of 10 specimens each, according to gutta-percha removal techniques: Group 1- Profile series 29 and Group 2- hand files and solvent. The amount of time for gutta-percha removal and the number of fractured instruments were evaluated. Radiographs were taken and the teeth were grooved longitudinally and split. The area of residual debris was measured using computer software. Results. The time for filling material removal was significantly shorter when Profile series 29 was used (P ⫽ .00). Regarding cleanliness, there were no statistical differences in the teeth halves evaluations (P ⬎ .05). Hand instruments cleaned the canals significantly better than Profiles, in the radiographic analysis considering the whole canal. Overall, the radiographic analysis showed a smaller percentage of residual debris than the teeth halves analysis. Conclusion. The Profile series 29 instruments proved to be faster than hand instruments in removing root filling materials; however, hand instruments yielded better root canal cleanliness. Some residual debris was not visualized by radiographs. (Oral Surg Oral Med Oral Pathol Oral Radiol Endod 2009;108:e46-e50)
Persistent apical periodontitis has been mainly caused by root canal bacteria that would have survived treatment; therefore, it has been frequently treated by using orthograde retreatment.1 Gutta-percha has been the most widely used endodontic filling material in conjunction with several sealers. Their removal from inadequately prepared and filled root canal systems has been essential in root canal retreatment because these filling materials would be likely to uncover remaining tissue or bacteria that may be responsible for periapical inflammation and posttreatment disease.2 However, their removal from apparently well-condensed root canals may be time consuming.3 Thus, a variety of instruments have been used to remove root-filling materials, including stainless steel hand instruments either alone or combined with solvents, rotary instruments, heat-carrying instruments, and ultrasonic devices.3-5
a
Endodontist, Bauru School of Dentistry, University of São Paulo, Brazil. b Professor of Endodontics, Bauru School of Dentistry, University of São Paulo, Brazil. Received for publication Feb 12, 2009; returned for revision Jul 5, 2009; accepted for publication Jul 16, 2009. 1079-2104/$ - see front matter © 2009 Published by Mosby, Inc. doi:10.1016/j.tripleo.2009.07.034
e46
Currently, the use of Ni-Ti rotary instruments has been recommended for gutta-percha removal and various studies have reported their efficacy, cleaning ability, and safety. Different systems, such as Quantec,6,7 Profile,8,9 ProTaper,2,10-12 GT files,2 RACE,10,13 and ProTaper Universal retreatment files9,14,15 have been evaluated for filling material removal and root canal reinstrumentation. The Profile series 29 has proved to rapidly prepare canals and to create a good 3-dimensional form with minimal canal transportation.16-18 Also, it has been evaluated for gutta-percha removal. In a previous study19 the Profile series 29 proved to be faster than hand instrumentation for gutta-percha removal in ovalshaped root canals; however, the mean values of filling material remnants were significantly higher, except in the apical third, where no difference occurred. Another study20 showed that Profile series 29 deeply penetrated into curved root canal compared to Gates-Glidden drills, during the initial phase of endodontic retreatment. The evaluation of gutta-percha removal has been performed by rendering the teeth transparent,10,11,13,14 using teeth halves,2,6,7,9,15,19 and using radiographs.6,7,12,15 In most of the studies, the residual filling material has been measured in mm2 using computer software.6,7,9,10-15 According to our knowledge, the literature has shown only a few studies investigating the use of Profile series 29 instruments in retreatment,19,20 and none has tested
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them in straight and circular-shaped canals. Therefore, the purpose of this study was to compare Profile series 29 instruments to hand instruments, in straight canal retreatment, regarding the cleanliness of root canal walls and the time consumed for gutta-percha removal, using both teeth halves and radiographs. MATERIALS AND METHODS Twenty extracted maxillary central incisors with single straight root canals and completely formed apices were selected. Preoperative buccolingual and mesiodistal radiographs were taken to confirm the presence of a single straight canal. The study was accomplished according to Bauru School of Dentistry’s Ethics Committee regulations concerning ex vivo experiments. Canal preparation The coronal access cavity was prepared using highspeed diamonds drills and water spray. A size 10 K-file (Dentsply Maillefer, Ballaigues, Switzerland) was placed into the canal until it was visible at the apical foramen. The working length was established 1 mm short of this length. The teeth were mounted in gypsum blocks. Root canals were prepared with a step-down technique, performed with a sequential use of .02 taper K-type files (Dentsply Maillefer, Ballaigues, Switzerland) up to size 40 at working length. Following, a step-back procedure in 1-mm increments was executed up to size 60. Canals were irrigated with 1 mL 1% NaOCl at each change of file. Then, canals were filled with 17% EDTA for 3 minutes and flushed with distilled water to remove the smear layer. Canal obturation Before obturation, canals were dried with absorbent paper points. The canals were filled with a zinc oxide eugenol sealer (Endométhasone- Septodont, SaintMaur-des-Fossés, France) and gutta-percha using a cold lateral-compactation technique. The access openings were sealed with a temporary filling material (Coltosol, Coltene-Whaledent, Cuyahoga Falls OH). A single operator prepared and filled all the canals. Buccolingual and mesiodistal radiographs were taken to examine the obturation quality and, in particular, the apical extent and degree of condensation. The distance between the X-ray cylinder and the film was 10 cm and the main beam formed a 90-degree angle with the film. The exposure time was 0.4 second and the films were automatically processed using Peri-Pro II X-ray processor (Air Techniques Inc, Melville, NY). All teeth were stored at 37°C in 100% humidity for 1 year.
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Retreatment technique The teeth were randomly divided into 2 groups of 10 specimens each, treated according to the following guttapercha removal techniques: Group 1—Profile .04 taper series 29 Profile .04 taper series 29 instruments (Tulsa Dental, Tulsa, OK) used with a 16:1 reduction hand piece powered by an electric motor (NT company, Chattanooga, TN) were used to remove the gutta-percha and sealer from the canals. Profile rotary instruments sizes 5 to 8 were sequentially used up to working length to remove the root filling materials. A 1500-rpm speed was used based on a previous study that evaluated Quantec rotary instruments for gutta-percha removal,6 but no solvent was applied. The instrument was introduced with a light apical pressure up to working length, and then, an up-and-down motion was used to remove all the filling materials. Group 2—Hand instruments Following placement of Xylol (0.5 mL) in the pulp chamber, a size 15 K-type file (Dentsply Maillefer) was inserted until it reached the working length. Then, Hedströem files (Dentsply Maillefer) from size 20 to size 40 were used in a filing motion toward the canal walls. The canals were irrigated with 1% NaOCl between files in both groups. Removal of filling materials was judged complete when no more gutta-percha/sealer could be seen on the last file used and the canal walls were smooth. Each hand instrument or Profile instrument was discarded after being used in 4 canals and a single operator prepared all samples. Evaluation Time taken to reach working length (T1). The time required for the size 5 instrument (in the Profile series 29 group) and size 15 K file (in the Hand group) to reach working length was measured (in seconds) with a stopwatch. Time for gutta-percha removal (T2). The time for the removal of gutta-percha and sealer was measured (in seconds) with a stopwatch. Total time (T1 ⫹ T2). The time to reach working length and for the complete removal of gutta-percha and sealer was calculated by adding T1 to T2. Fractured instruments. The number of fractured instruments was recorded for each group. Canal wall cleanliness. After filling removal, buccolingual and mesiodistal radiographs were taken as pre-
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Table I. Means in seconds and SDs for the time to reach working length (T1), time for gutta-percha removal (T2), and total time (T total) T1 T2 T total
Profile (mean ⫾ SD)
Hand (mean ⫾ SD)
51.1 ⫾ 12.8 301.0 ⫾ 72.4 352.1 ⫾ 68.3
105.5 ⫾ 40.0 596.0 ⫾ 70.6 701.5 ⫾ 95.9
cleanliness evaluation (teeth halves ⫻ buccolingual radiographs ⫻ mesiodistal radiographs) using Friedman test and Student-Newman-Keuls test. The significance level was set at P less than .05. These tests were used because the data failed to pass in the normality test and equal variance test. RESULTS Time taken to reach working length (T1) The Profile series 29 reached working length significantly faster than hand instruments (P ⫽ .000). Fig. 1. Digitized tooth halves.
viously described and the teeth were grooved longitudinally with a low-speed diamond disc and vertically split with a chisel. Each half of the root and each radiograph were digitized using a scanner (4C- Hewlett Packard, Palo Alto, CA) with standardized resolution set at 600 dpi, brightness at 132 and contrast at 142, using the software Deskscan 2.9 (Hewlett Packard) (Figure 1). The images were evaluated using Sigma Scan software (Jandel Scientific, San Rafael CA). The canal was divided into coronal, middle, and apical thirds from the cemento-enamel junction to the terminus of the apical preparation, and each of them was separately evaluated. The residual filling material debris was outlined by a single operator who was blinded to group assignment, and the area (mm2) was calculated by the software. The total areas of the thirds were calculated and then, the percentage of the area covered by the remnant debris was computed. The percentage of debris in the whole canal was also calculated using the value of total debris and the value of the canal total area. Statistical analysis Mann-Whitney test was used to compare the operative time and the percentage of debris between the 2 groups. The values referred to both groups (Profile and hand) were pooled to compare the different methods of
Time for gutta-percha removal (T2) The Profile series 29 removed the filling material significantly more rapidly than hand instruments (P ⫽ .000). Total time for gutta-percha removal The Profile series 29 was significantly faster than hand files (P ⫽ .000). The means and standard deviations for the retreatment time are shown in Table I. Fractured instruments No instrument fractured during the study. Canal wall cleanliness Analysis of the roots. There were no statistical differences between the Profile series 29 and hand instrument groups in the cervical (P ⫽ .345), middle (P ⫽ 1.000), and apical (P ⫽ .082) thirds and also in the whole canal (P ⫽ .427). Analysis of radiographs. Considering the whole canal, the hand files group performed significantly better than Profile series 29 group in both buccolingual (P ⫽ .011) and mesiodistal (P ⫽ .009) radiograph evaluations. The hand files group performed significantly better than Profile series 29 group in the cervical third, considering buccolingual radiographs (P ⫽ .043) and in apical third, considering mesiodistal radiographs (P ⫽ .023). There were no statistical differences between Profile series 29 and hand instrument groups in the middle (P ⫽
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Table II. Means and SDs for the filling debris areas/canal areas ratios (%) in the cervical, middle, and apical thirds and in whole canal Buccolingual radiographs (mean ⫾ SD)
Halves (mean ⫾ SD) Cervical Middle Apical Whole canal
Profile
Hand
Profile
Hand
Profile
Hand
20.5 ⫾ 13.3 19.7 ⫾ 17.5 24.9 ⫾ 19.4 21.3 ⫾ 14.1
15.5 ⫾ 15.2 20.8 ⫾ 18.9 10.1 ⫾ 11.3 15.5 ⫾ 14.6
5.99 ⫾ 0.79 11.63 ⫾ 15.58 19.32 ⫾ 20.05 9.52 ⫾ 6.74
0.16 ⫾ 0.56 3.80 ⫾ 6.81 1.32 ⫾ 2.39 2.26 ⫾ 3.34
5.40 ⫾ 6.55 13.95 ⫾ 17.57 17.90 ⫾ 13.28 11.03 ⫾ 7.44
1.32 ⫾ 2.39 3.66 ⫾ 5.88 5.97 ⫾ 7.84 3.04 ⫾ 2.71
Table III. Means and SDs for the filling debris areas/ canal areas ratios (%) according to the different methods of analysis
Cervical Middle Apical Whole canal
Mesiodistal radiographs (mean ⫾ SD)
Halves (mean ⫾ SD)
Buccolingual radiographs (mean ⫾ SD)
Mesiodistal radiographs (mean ⫾ SD)
17.98 ⫾ 14.16 20.24 ⫾ 17.7 17.50 ⫾ 17.20 18.42 ⫾ 14.24
3.08 ⫾ 6.76 7.72 ⫾ 12.40 12.1 ⫾ 16.70 5.89 ⫾ 6.37
3.36 ⫾ 5.30 8.81 ⫾ 13.8 11.90 ⫾ 12.30 7.04 ⫾ 6.82
.569) and apical (P ⫽ .103) thirds, considering buccolingual radiographs and, in cervical (P ⫽ .053) and middle (P ⫽ .384) thirds, considering mesiodistal radiographs. The means and standard deviations concerning canal wall cleanliness are shown in Table II. Comparison of evaluation methods (teeth halves, buccolingual radiographs, and mesiodistal radiographs). The means of residual filling materials (%) in the radiographic analysis were lower than those in the teeth halves analysis (Table III). There were no significant differences among the evaluation methods in the apical third (P ⫽ .199). There were significant differences among the analyses in the cervical third (P ⫽ .000), middle third (P ⫽ .000), and in the whole canal (P ⫽ .002), where the values of the teeth halves were significantly higher than those of radiographs (P ⬍ .05). There were no statistical differences between the radiographs in different directions (buccolingual and mesiodistal) (P ⬎ .05). DISCUSSION As reported in previous studies,19,20 the Profile series 29 instruments were faster than hand instruments in removing gutta-percha fillings. When evaluating rotary Ni-Ti systems, many studies proved that they had been faster than hand instruments for gutta-percha removal.7,9,10,11 This study’s mean values for the retreating time were consistent with other studies.7,19 The speed used was in accordance with a previous study,6 although other studies used lower (500 rpm)19 and higher (3000 rpm)20 rotary speeds.
The solvent was not used in conjunction with Profile series 29 instruments according to a study14 that evaluated the efficiency of ProTaper Universal retreatment and showed that canal wall cleanliness was less satisfactory in the groups where solvent had been used. When solvents had been used they formed a thin film of filling material over the canal walls. This could reduce the action of intracanal medicaments and the adaptation of the subsequent filling material on the root canal walls. No instrument fractured, similar to a previous study19 where no Profile series 29 had fractured. However, these latter authors reported that some of them had deformed, mainly the larger ones. On the other hand, in another study,20 2 profile series 29 instruments fractured probably as a result of the instability caused by the gutta-percha mass that had been inadvertently stuck on the tip of the instrument. In this study, the teeth were longitudinally split and the residual gutta-percha and sealer areas were measured. Although the area measurement has not been the most precise method, it has minimized the subjectivity regarding the use of a scoring system based on scales, which has been used in many studies.10 Radiographic analysis was also executed by using the measurement of filling material areas (radiodense) with a computer software. According to Ferreira et al.8 and Schirrmeister et al.,13 this method has been more reliable because the residual gutta-percha or sealer would be lost as a result of the roots splitting. However, it has had limitations, because radiographic images have provided only 2-dimensional information about a 3-dimensional structure and could be subjected to magnification and distortion. In addition, small volumes of debris could not be visualized.12 Regarding this former statement, this study showed that the means of residual filling materials were smaller in the radiographic analysis than in the teeth halves analysis. When cleanliness was evaluated, there were no statistical differences between groups, in teeth halves analysis. Hand instruments showed better cleanliness only in some radiographic analyses: when considering the whole canal in both directions, the cervical third in
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buccolingual radiographs, and the apical third in mesiodistal radiographs. In a study19 using oval-shaped canals, hand instruments performed significantly better than profile series 29, in cervical and middle thirds. The smaller amount of residual filling materials in the hand instruments group could be because the Hedströem files could be manipulated against the walls, removing the debris on them. Also, the design of their flutes would facilitate the removal of gutta-percha. Comparing other rotary Ni-Ti to hand instruments, some authors also verified that hand instruments more effectively cleaned the canals7; however, some studies found similar results between them8,13 and others found better cleanliness with rotary Ni-Ti instruments.9,11,15 CONCLUSIONS Overall, under the experimental conditions of this study, hand files performed significantly better than Profile series 29 instruments in the radiographic analysis; however, there were no statistical differences in the teeth halves analysis. Although Profile series 29 instruments seem to be safe, time-saving, and helpful for gutta-percha removal in root canal retreatment, further studies are needed. REFERENCES 1. Friedman S. Considerations and concepts of case selection in the management of post-treatment endodontic disease (treatment failure). Endodontic Topics 2002;1:54-78. 2. Hülsmann M, Bluhm V. Efficacy, cleaning ability and safety of different rotary NiTi instruments in root canal retreatment. Int Endod J 2004;37:468-76. 3. Ladley RW, Campbell AD, Hicks ML, Li SH. Effectiveness of halothane used with ultrasonic or hand instrumentation to remove gutta-percha from the root canal. J Endod 1991;17:221-4. 4. Friedman S, Stabholz A, Tamse A. Endodontic retreatment— case selection and technique. Part 3: Retreatment techniques. J Endod 1990;16:543-9. 5. Hülsmann 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. 6. Bramante CM, Betti LV. Efficacy of Quantec rotary instruments for gutta-percha removal. Int Endod J 2000;33:463-7. 7. Betti LV, Bramante CM. Quantec SC rotary instruments versus hand files for gutta-percha removal in root canal retreatment. Int Endod J 2001;34:514-9.
8. Ferreira JJ, Rhodes JS, Pitt Ford TR. The efficacy of gutta-percha removal using ProFiles. Int Endod J 2001;34:267-74. 9. Giuliani V, Cocchetti R, Pagavino G. Efficacy of ProTaper Universal Retreatment Files in removing materials during root canal retreatment. J Endod 2008;34:1381-4. 10. Schirrmeister JF, Wrbas KT, Meyer KM, Altenburger MJ, Hellwig E. Efficacy of different rotary instruments for gutta-percha removal in root canal retreatment. J Endod 2006;32:469-72. 11. Tas¸demir T, Er K, Yildirim T, Çelik D. Efficacy of three rotary NiTi instruments in removing gutta-percha from root canals. Int Endod J 2008;41:191-6. 12. Gergi R, Sabbagh C. Effectiveness of two nickel-titanium rotary instruments and a hand file for removing gutta-percha in severely curved root canals during retreatment: an ex vivo study. Int Endod J 2007;40:532-7. 13. Schirrmeister JF, Meyer KM, Hermanns P, Altenburger MJ, Wrbas KT. Effectiveness of hand and rotary instrumentation for removing a new synthetic polymer-based root canal obturation material (Epiphany) during retreatment. Int Endod J 2006;39: 160-6. 14. 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;41:288-96. 15. Só MVR, Saran C, Magro ML, Vier-Pelisser FV, Munhoz M. Efficacy of ProTaper retreatment system in root canals filled with gutta-percha and two endodontic sealers. J Endod 2008;34: 1223-5. 16. Thompson AS, Dummer PM. Shaping ability of Profile .04 Taper Series 29 rotary nickel-titanium instruments in simulated root canals: Part 1. Int Endod J 1997;30:1-7. 17. Thompson AS, Dummer PM. Shaping ability of Profile Taper .04 Series 29 rotary nickel-titanium instruments in simulated root canals: Part 2. Int Endod J 1997;30:8-15. 18. Iqbal MK, Firic S, Tulcan J, Karabucak B, Kim S. Comparison of apical transportation between ProFile and ProTaper NiTi rotary instruments. Int Endod J 2004;37:359-64. 19. Zmener O, Pameijer CH, Banegas G. Retreatment efficacy of hand versus automated instrumentation in oval-shaped root canals: an ex vivo study. Int Endod J 2006;39:521-6. 20. Valois CRA, Navarro M, Ramos AA, de Castro AJR, Gahyva SM. Effectiveness of the Profile .04 taper series 29 files in removal of gutta-percha root fillings during curved root canal retreatment. Braz Dent J 2001;12:95-9. Reprint requests: Luciana Viti Betti, DDS, PhD Bauru School of Dentistry University of São Paulo Al. Octávio Pinheiro Brisola 9-75 17012-901 Bauru, São Paulo, Brazil [email protected]
Objective. The aim of this study was to compare Profile .04 taper series 29 instruments and hand files for gutta-percha removal. Study design. Twenty maxillary central incisors with a single straight canal were instrumented and filled. The teeth were divided into 2 groups of 10 specimens each, according to gutta-percha removal techniques: Group 1- Profile series 29 and Group 2- hand files and solvent. The amount of time for gutta-percha removal and the number of fractured instruments were evaluated. Radiographs were taken and the teeth were grooved longitudinally and split. The area of residual debris was measured using computer software. Results. The time for filling material removal was significantly shorter when Profile series 29 was used (P ⫽ .00). Regarding cleanliness, there were no statistical differences in the teeth halves evaluations (P ⬎ .05). Hand instruments cleaned the canals significantly better than Profiles, in the radiographic analysis considering the whole canal. Overall, the radiographic analysis showed a smaller percentage of residual debris than the teeth halves analysis. Conclusion. The Profile series 29 instruments proved to be faster than hand instruments in removing root filling materials; however, hand instruments yielded better root canal cleanliness. Some residual debris was not visualized by radiographs. (Oral Surg Oral Med Oral Pathol Oral Radiol Endod 2009;108:e46-e50)
Persistent apical periodontitis has been mainly caused by root canal bacteria that would have survived treatment; therefore, it has been frequently treated by using orthograde retreatment.1 Gutta-percha has been the most widely used endodontic filling material in conjunction with several sealers. Their removal from inadequately prepared and filled root canal systems has been essential in root canal retreatment because these filling materials would be likely to uncover remaining tissue or bacteria that may be responsible for periapical inflammation and posttreatment disease.2 However, their removal from apparently well-condensed root canals may be time consuming.3 Thus, a variety of instruments have been used to remove root-filling materials, including stainless steel hand instruments either alone or combined with solvents, rotary instruments, heat-carrying instruments, and ultrasonic devices.3-5
a
Endodontist, Bauru School of Dentistry, University of São Paulo, Brazil. b Professor of Endodontics, Bauru School of Dentistry, University of São Paulo, Brazil. Received for publication Feb 12, 2009; returned for revision Jul 5, 2009; accepted for publication Jul 16, 2009. 1079-2104/$ - see front matter © 2009 Published by Mosby, Inc. doi:10.1016/j.tripleo.2009.07.034
e46
Currently, the use of Ni-Ti rotary instruments has been recommended for gutta-percha removal and various studies have reported their efficacy, cleaning ability, and safety. Different systems, such as Quantec,6,7 Profile,8,9 ProTaper,2,10-12 GT files,2 RACE,10,13 and ProTaper Universal retreatment files9,14,15 have been evaluated for filling material removal and root canal reinstrumentation. The Profile series 29 has proved to rapidly prepare canals and to create a good 3-dimensional form with minimal canal transportation.16-18 Also, it has been evaluated for gutta-percha removal. In a previous study19 the Profile series 29 proved to be faster than hand instrumentation for gutta-percha removal in ovalshaped root canals; however, the mean values of filling material remnants were significantly higher, except in the apical third, where no difference occurred. Another study20 showed that Profile series 29 deeply penetrated into curved root canal compared to Gates-Glidden drills, during the initial phase of endodontic retreatment. The evaluation of gutta-percha removal has been performed by rendering the teeth transparent,10,11,13,14 using teeth halves,2,6,7,9,15,19 and using radiographs.6,7,12,15 In most of the studies, the residual filling material has been measured in mm2 using computer software.6,7,9,10-15 According to our knowledge, the literature has shown only a few studies investigating the use of Profile series 29 instruments in retreatment,19,20 and none has tested
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them in straight and circular-shaped canals. Therefore, the purpose of this study was to compare Profile series 29 instruments to hand instruments, in straight canal retreatment, regarding the cleanliness of root canal walls and the time consumed for gutta-percha removal, using both teeth halves and radiographs. MATERIALS AND METHODS Twenty extracted maxillary central incisors with single straight root canals and completely formed apices were selected. Preoperative buccolingual and mesiodistal radiographs were taken to confirm the presence of a single straight canal. The study was accomplished according to Bauru School of Dentistry’s Ethics Committee regulations concerning ex vivo experiments. Canal preparation The coronal access cavity was prepared using highspeed diamonds drills and water spray. A size 10 K-file (Dentsply Maillefer, Ballaigues, Switzerland) was placed into the canal until it was visible at the apical foramen. The working length was established 1 mm short of this length. The teeth were mounted in gypsum blocks. Root canals were prepared with a step-down technique, performed with a sequential use of .02 taper K-type files (Dentsply Maillefer, Ballaigues, Switzerland) up to size 40 at working length. Following, a step-back procedure in 1-mm increments was executed up to size 60. Canals were irrigated with 1 mL 1% NaOCl at each change of file. Then, canals were filled with 17% EDTA for 3 minutes and flushed with distilled water to remove the smear layer. Canal obturation Before obturation, canals were dried with absorbent paper points. The canals were filled with a zinc oxide eugenol sealer (Endométhasone- Septodont, SaintMaur-des-Fossés, France) and gutta-percha using a cold lateral-compactation technique. The access openings were sealed with a temporary filling material (Coltosol, Coltene-Whaledent, Cuyahoga Falls OH). A single operator prepared and filled all the canals. Buccolingual and mesiodistal radiographs were taken to examine the obturation quality and, in particular, the apical extent and degree of condensation. The distance between the X-ray cylinder and the film was 10 cm and the main beam formed a 90-degree angle with the film. The exposure time was 0.4 second and the films were automatically processed using Peri-Pro II X-ray processor (Air Techniques Inc, Melville, NY). All teeth were stored at 37°C in 100% humidity for 1 year.
Betti et al. e47
Retreatment technique The teeth were randomly divided into 2 groups of 10 specimens each, treated according to the following guttapercha removal techniques: Group 1—Profile .04 taper series 29 Profile .04 taper series 29 instruments (Tulsa Dental, Tulsa, OK) used with a 16:1 reduction hand piece powered by an electric motor (NT company, Chattanooga, TN) were used to remove the gutta-percha and sealer from the canals. Profile rotary instruments sizes 5 to 8 were sequentially used up to working length to remove the root filling materials. A 1500-rpm speed was used based on a previous study that evaluated Quantec rotary instruments for gutta-percha removal,6 but no solvent was applied. The instrument was introduced with a light apical pressure up to working length, and then, an up-and-down motion was used to remove all the filling materials. Group 2—Hand instruments Following placement of Xylol (0.5 mL) in the pulp chamber, a size 15 K-type file (Dentsply Maillefer) was inserted until it reached the working length. Then, Hedströem files (Dentsply Maillefer) from size 20 to size 40 were used in a filing motion toward the canal walls. The canals were irrigated with 1% NaOCl between files in both groups. Removal of filling materials was judged complete when no more gutta-percha/sealer could be seen on the last file used and the canal walls were smooth. Each hand instrument or Profile instrument was discarded after being used in 4 canals and a single operator prepared all samples. Evaluation Time taken to reach working length (T1). The time required for the size 5 instrument (in the Profile series 29 group) and size 15 K file (in the Hand group) to reach working length was measured (in seconds) with a stopwatch. Time for gutta-percha removal (T2). The time for the removal of gutta-percha and sealer was measured (in seconds) with a stopwatch. Total time (T1 ⫹ T2). The time to reach working length and for the complete removal of gutta-percha and sealer was calculated by adding T1 to T2. Fractured instruments. The number of fractured instruments was recorded for each group. Canal wall cleanliness. After filling removal, buccolingual and mesiodistal radiographs were taken as pre-
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Table I. Means in seconds and SDs for the time to reach working length (T1), time for gutta-percha removal (T2), and total time (T total) T1 T2 T total
Profile (mean ⫾ SD)
Hand (mean ⫾ SD)
51.1 ⫾ 12.8 301.0 ⫾ 72.4 352.1 ⫾ 68.3
105.5 ⫾ 40.0 596.0 ⫾ 70.6 701.5 ⫾ 95.9
cleanliness evaluation (teeth halves ⫻ buccolingual radiographs ⫻ mesiodistal radiographs) using Friedman test and Student-Newman-Keuls test. The significance level was set at P less than .05. These tests were used because the data failed to pass in the normality test and equal variance test. RESULTS Time taken to reach working length (T1) The Profile series 29 reached working length significantly faster than hand instruments (P ⫽ .000). Fig. 1. Digitized tooth halves.
viously described and the teeth were grooved longitudinally with a low-speed diamond disc and vertically split with a chisel. Each half of the root and each radiograph were digitized using a scanner (4C- Hewlett Packard, Palo Alto, CA) with standardized resolution set at 600 dpi, brightness at 132 and contrast at 142, using the software Deskscan 2.9 (Hewlett Packard) (Figure 1). The images were evaluated using Sigma Scan software (Jandel Scientific, San Rafael CA). The canal was divided into coronal, middle, and apical thirds from the cemento-enamel junction to the terminus of the apical preparation, and each of them was separately evaluated. The residual filling material debris was outlined by a single operator who was blinded to group assignment, and the area (mm2) was calculated by the software. The total areas of the thirds were calculated and then, the percentage of the area covered by the remnant debris was computed. The percentage of debris in the whole canal was also calculated using the value of total debris and the value of the canal total area. Statistical analysis Mann-Whitney test was used to compare the operative time and the percentage of debris between the 2 groups. The values referred to both groups (Profile and hand) were pooled to compare the different methods of
Time for gutta-percha removal (T2) The Profile series 29 removed the filling material significantly more rapidly than hand instruments (P ⫽ .000). Total time for gutta-percha removal The Profile series 29 was significantly faster than hand files (P ⫽ .000). The means and standard deviations for the retreatment time are shown in Table I. Fractured instruments No instrument fractured during the study. Canal wall cleanliness Analysis of the roots. There were no statistical differences between the Profile series 29 and hand instrument groups in the cervical (P ⫽ .345), middle (P ⫽ 1.000), and apical (P ⫽ .082) thirds and also in the whole canal (P ⫽ .427). Analysis of radiographs. Considering the whole canal, the hand files group performed significantly better than Profile series 29 group in both buccolingual (P ⫽ .011) and mesiodistal (P ⫽ .009) radiograph evaluations. The hand files group performed significantly better than Profile series 29 group in the cervical third, considering buccolingual radiographs (P ⫽ .043) and in apical third, considering mesiodistal radiographs (P ⫽ .023). There were no statistical differences between Profile series 29 and hand instrument groups in the middle (P ⫽
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Table II. Means and SDs for the filling debris areas/canal areas ratios (%) in the cervical, middle, and apical thirds and in whole canal Buccolingual radiographs (mean ⫾ SD)
Halves (mean ⫾ SD) Cervical Middle Apical Whole canal
Profile
Hand
Profile
Hand
Profile
Hand
20.5 ⫾ 13.3 19.7 ⫾ 17.5 24.9 ⫾ 19.4 21.3 ⫾ 14.1
15.5 ⫾ 15.2 20.8 ⫾ 18.9 10.1 ⫾ 11.3 15.5 ⫾ 14.6
5.99 ⫾ 0.79 11.63 ⫾ 15.58 19.32 ⫾ 20.05 9.52 ⫾ 6.74
0.16 ⫾ 0.56 3.80 ⫾ 6.81 1.32 ⫾ 2.39 2.26 ⫾ 3.34
5.40 ⫾ 6.55 13.95 ⫾ 17.57 17.90 ⫾ 13.28 11.03 ⫾ 7.44
1.32 ⫾ 2.39 3.66 ⫾ 5.88 5.97 ⫾ 7.84 3.04 ⫾ 2.71
Table III. Means and SDs for the filling debris areas/ canal areas ratios (%) according to the different methods of analysis
Cervical Middle Apical Whole canal
Mesiodistal radiographs (mean ⫾ SD)
Halves (mean ⫾ SD)
Buccolingual radiographs (mean ⫾ SD)
Mesiodistal radiographs (mean ⫾ SD)
17.98 ⫾ 14.16 20.24 ⫾ 17.7 17.50 ⫾ 17.20 18.42 ⫾ 14.24
3.08 ⫾ 6.76 7.72 ⫾ 12.40 12.1 ⫾ 16.70 5.89 ⫾ 6.37
3.36 ⫾ 5.30 8.81 ⫾ 13.8 11.90 ⫾ 12.30 7.04 ⫾ 6.82
.569) and apical (P ⫽ .103) thirds, considering buccolingual radiographs and, in cervical (P ⫽ .053) and middle (P ⫽ .384) thirds, considering mesiodistal radiographs. The means and standard deviations concerning canal wall cleanliness are shown in Table II. Comparison of evaluation methods (teeth halves, buccolingual radiographs, and mesiodistal radiographs). The means of residual filling materials (%) in the radiographic analysis were lower than those in the teeth halves analysis (Table III). There were no significant differences among the evaluation methods in the apical third (P ⫽ .199). There were significant differences among the analyses in the cervical third (P ⫽ .000), middle third (P ⫽ .000), and in the whole canal (P ⫽ .002), where the values of the teeth halves were significantly higher than those of radiographs (P ⬍ .05). There were no statistical differences between the radiographs in different directions (buccolingual and mesiodistal) (P ⬎ .05). DISCUSSION As reported in previous studies,19,20 the Profile series 29 instruments were faster than hand instruments in removing gutta-percha fillings. When evaluating rotary Ni-Ti systems, many studies proved that they had been faster than hand instruments for gutta-percha removal.7,9,10,11 This study’s mean values for the retreating time were consistent with other studies.7,19 The speed used was in accordance with a previous study,6 although other studies used lower (500 rpm)19 and higher (3000 rpm)20 rotary speeds.
The solvent was not used in conjunction with Profile series 29 instruments according to a study14 that evaluated the efficiency of ProTaper Universal retreatment and showed that canal wall cleanliness was less satisfactory in the groups where solvent had been used. When solvents had been used they formed a thin film of filling material over the canal walls. This could reduce the action of intracanal medicaments and the adaptation of the subsequent filling material on the root canal walls. No instrument fractured, similar to a previous study19 where no Profile series 29 had fractured. However, these latter authors reported that some of them had deformed, mainly the larger ones. On the other hand, in another study,20 2 profile series 29 instruments fractured probably as a result of the instability caused by the gutta-percha mass that had been inadvertently stuck on the tip of the instrument. In this study, the teeth were longitudinally split and the residual gutta-percha and sealer areas were measured. Although the area measurement has not been the most precise method, it has minimized the subjectivity regarding the use of a scoring system based on scales, which has been used in many studies.10 Radiographic analysis was also executed by using the measurement of filling material areas (radiodense) with a computer software. According to Ferreira et al.8 and Schirrmeister et al.,13 this method has been more reliable because the residual gutta-percha or sealer would be lost as a result of the roots splitting. However, it has had limitations, because radiographic images have provided only 2-dimensional information about a 3-dimensional structure and could be subjected to magnification and distortion. In addition, small volumes of debris could not be visualized.12 Regarding this former statement, this study showed that the means of residual filling materials were smaller in the radiographic analysis than in the teeth halves analysis. When cleanliness was evaluated, there were no statistical differences between groups, in teeth halves analysis. Hand instruments showed better cleanliness only in some radiographic analyses: when considering the whole canal in both directions, the cervical third in
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buccolingual radiographs, and the apical third in mesiodistal radiographs. In a study19 using oval-shaped canals, hand instruments performed significantly better than profile series 29, in cervical and middle thirds. The smaller amount of residual filling materials in the hand instruments group could be because the Hedströem files could be manipulated against the walls, removing the debris on them. Also, the design of their flutes would facilitate the removal of gutta-percha. Comparing other rotary Ni-Ti to hand instruments, some authors also verified that hand instruments more effectively cleaned the canals7; however, some studies found similar results between them8,13 and others found better cleanliness with rotary Ni-Ti instruments.9,11,15 CONCLUSIONS Overall, under the experimental conditions of this study, hand files performed significantly better than Profile series 29 instruments in the radiographic analysis; however, there were no statistical differences in the teeth halves analysis. Although Profile series 29 instruments seem to be safe, time-saving, and helpful for gutta-percha removal in root canal retreatment, further studies are needed. REFERENCES 1. Friedman S. Considerations and concepts of case selection in the management of post-treatment endodontic disease (treatment failure). Endodontic Topics 2002;1:54-78. 2. Hülsmann M, Bluhm V. Efficacy, cleaning ability and safety of different rotary NiTi instruments in root canal retreatment. Int Endod J 2004;37:468-76. 3. Ladley RW, Campbell AD, Hicks ML, Li SH. Effectiveness of halothane used with ultrasonic or hand instrumentation to remove gutta-percha from the root canal. J Endod 1991;17:221-4. 4. Friedman S, Stabholz A, Tamse A. Endodontic retreatment— case selection and technique. Part 3: Retreatment techniques. J Endod 1990;16:543-9. 5. Hülsmann 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. 6. Bramante CM, Betti LV. Efficacy of Quantec rotary instruments for gutta-percha removal. Int Endod J 2000;33:463-7. 7. Betti LV, Bramante CM. Quantec SC rotary instruments versus hand files for gutta-percha removal in root canal retreatment. Int Endod J 2001;34:514-9.
8. Ferreira JJ, Rhodes JS, Pitt Ford TR. The efficacy of gutta-percha removal using ProFiles. Int Endod J 2001;34:267-74. 9. Giuliani V, Cocchetti R, Pagavino G. Efficacy of ProTaper Universal Retreatment Files in removing materials during root canal retreatment. J Endod 2008;34:1381-4. 10. Schirrmeister JF, Wrbas KT, Meyer KM, Altenburger MJ, Hellwig E. Efficacy of different rotary instruments for gutta-percha removal in root canal retreatment. J Endod 2006;32:469-72. 11. Tas¸demir T, Er K, Yildirim T, Çelik D. Efficacy of three rotary NiTi instruments in removing gutta-percha from root canals. Int Endod J 2008;41:191-6. 12. Gergi R, Sabbagh C. Effectiveness of two nickel-titanium rotary instruments and a hand file for removing gutta-percha in severely curved root canals during retreatment: an ex vivo study. Int Endod J 2007;40:532-7. 13. Schirrmeister JF, Meyer KM, Hermanns P, Altenburger MJ, Wrbas KT. Effectiveness of hand and rotary instrumentation for removing a new synthetic polymer-based root canal obturation material (Epiphany) during retreatment. Int Endod J 2006;39: 160-6. 14. 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;41:288-96. 15. Só MVR, Saran C, Magro ML, Vier-Pelisser FV, Munhoz M. Efficacy of ProTaper retreatment system in root canals filled with gutta-percha and two endodontic sealers. J Endod 2008;34: 1223-5. 16. Thompson AS, Dummer PM. Shaping ability of Profile .04 Taper Series 29 rotary nickel-titanium instruments in simulated root canals: Part 1. Int Endod J 1997;30:1-7. 17. Thompson AS, Dummer PM. Shaping ability of Profile Taper .04 Series 29 rotary nickel-titanium instruments in simulated root canals: Part 2. Int Endod J 1997;30:8-15. 18. Iqbal MK, Firic S, Tulcan J, Karabucak B, Kim S. Comparison of apical transportation between ProFile and ProTaper NiTi rotary instruments. Int Endod J 2004;37:359-64. 19. Zmener O, Pameijer CH, Banegas G. Retreatment efficacy of hand versus automated instrumentation in oval-shaped root canals: an ex vivo study. Int Endod J 2006;39:521-6. 20. Valois CRA, Navarro M, Ramos AA, de Castro AJR, Gahyva SM. Effectiveness of the Profile .04 taper series 29 files in removal of gutta-percha root fillings during curved root canal retreatment. Braz Dent J 2001;12:95-9. Reprint requests: Luciana Viti Betti, DDS, PhD Bauru School of Dentistry University of São Paulo Al. Octávio Pinheiro Brisola 9-75 17012-901 Bauru, São Paulo, Brazil [email protected]