SCANNING VOL. 9999, 1–6 (2014) © Wiley Periodicals, Inc.
Efficacy of Reciprocating and Rotary Systems for Removing Root Filling Material: A Micro-Computed Tomography Study D. HELVACIOGLU-YIGIT,1 A. YILMAZ,2 G. KIZILTAS-SENDUR,3,4 O. S. ASLAN,3,4
AND
P. V. ABBOTT5
1
Faculty of Dentistry, Department of Endodontics, Kocaeli University, Kocaeli, Turkey Faculty of Dentistry, Department of Endodontics, Istanbul University, Istanbul, Turkey 3 Faculty of Engineering and Natural Sciences, Department of Mechatronics Engineering, Sabanci University, Istanbul, Turkey 4 Nanotechnology Research and Application Center, Sabanci University, ˙Istanbul, Turkey 5 School of Dentistry, University of Western Australia, Nedlands, Western Australia, Australia 2
Summary: This study aimed to use micro-computed tomography (micro-CT) imaging to evaluate the efficacy of the reciprocating and rotary systems for the removal of root filling materials in comparison with hand files. Thirty maxillary incisor teeth were prepared with ProTaper Universal (PTU) system, filled using cold lateral condensation and randomly divided into three groups of ten teeth each. The root fillings were removed with WaveOne Reciprocating and ProTaper Universal Retreatment (PTU-R) systems and hand files. Micro-CT was used to scan the specimens before and after each treatment step. Percentage of volume of residual root filling was measured. The operating time was recorded. PTU-R instruments yielded better results for removing filling material, even though there was no statistically significant difference between PTU-R and WaveOne groups. Reciprocating and rotary systems showed similar performances in terms of efficacy and operating time for root filling removal. SCANNING 9999:XX–XX, 2014. © 2014 Wiley Periodicals, Inc. Key words: dentistry, imaging, three-dimensional (3D) reconstruction
Introduction The objectives of endodontic re-treatment include complete removal of the existing root filling material to Contract grant sponsor: Kocaeli University Research Fund; Contract grant numbers: HDP 2013-103, 2013-076. Conflicts of interest: None. Address for reprints: Dilek Helvacioglu-Yigit, Faculty of Dentistry, Department of Endodontics, Kocaeli University, Kocaeli, Turkey. E-mail: [email protected], [email protected] Received 21 June 2014; Accepted with revision 1 August 2014 DOI: 10.1002/sca.21157 Published online XX Month Year in Wiley Online Library (wileyonlinelibrary.com).
the apical foramen followed by biomechanical preparation, disinfection, and subsequently re-filling of the root canals (Ruddle, 2004). However, some filling material may remain on the canal walls, which may result in harboring of micro-organisms and less favorable treatment outcomes. Several instrumentation techniques have been described to improve the removal of root fillings. These include manual instrumentation (Kfir et al., 2012; Rodig et al., 2014) ultrasonic preparation (Cavenago et al., 2014), use of heat-carriers (Guess, 2004), and Ni-Ti rotary instruments (Hulsmann and Bluhm, 2004; Saad et al., 2007; Kfir et al., 2012; Mollo et al., 2012; Rodig et al., 2014). Some studies have demonstrated the effective use of specially designed rotary re-treatment instruments (Giuliani et al., 2008; Gu et al., 2008). They have also been reported to be less time-consuming than manual instrumentation (Mollo et al., 2012). One such system, the Protaper Universal Re-treatment system (PTU-R; Dentsply Maillefer, Ballaigues, Switzerland) consists of three files: D1-30/.09, D2-25/.08, and D3-20/.07. The D1 is designed with an active working tip which allows the instrument to penetrate into the filling material. The effectiveness of re-treatment has been evaluated by a variety of techniques in experimental studies: clearing the teeth by demineralization (Gu et al., 2008), radiographic assessment (Mollo et al., 2012), longitudinal sectioning prior to photographic and microscopic analysis (Giuliani et al., 2008; Hulsmann and Bluhm, 2004; Saad et al., 2007; Zuolo et al., 2013), and a combination of these techniques (Kfir et al., 2012). In some re-treatment studies, the precise volume of residual filling material was determined with the use of micro-computed tomography (micro-CT), which allows non-invasive three-dimensional (3D) quantitative evaluation (Hammad et al., 2008; Roggendorf et al., 2010; Ma et al., 2012; Rodig et al., 2012; Solomonov et al., 2012; Saglam et al., 2013; Rodig et al., 2014). Moreover, by allowing observation of the canal during
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the various stages of root canal re-treatment, this method overcomes the limitations of other assessment methods. The WaveOne instruments (Dentsply Maillefer, Ballaigues, Switzerland), manufactured with M-Wire Ni-Ti alloy, were designed to work with a reciprocation action rather than with rotary action (Kim et al., 2013). The efficacy of reciprocation and rotary techniques using Reciproc and Mtwo R instruments (both from VDW, Munich, Germany) for removing root filling materials has been investigated before and concluded that the reciprocating technique and hand instrumentation combined with Gates–Glidden drills removed more filling material than the rotary technique during re-treatment (Zuolo et al., 2013). However, the efficacy of WaveOne instruments in root canal re-treatment has not been yet investigated. Hence, the purpose of the present study was to extend these observations by evaluating the efficacy of other reciprocating and rotary instruments, namely the WaveOne and PTU-R instruments, for the removal of root canal filling material in comparison with hand files using micro-CT imaging. The times taken to remove root filling material were also compared.
Materials and Methods Fifty fully developed maxillary incisors with intact apices were obtained from the collections of the Department of Oral and MaxilloFacial Surgery, Kocaeli University. The teeth were extracted for clinical reasons in accordance with appropriate consent procedures. Teeth which had undergone root canal treatment, or had root caries or restorations were excluded from the study. Teeth were scanned prior to any treatment by using a Skyscan 1172 high-resolution micro-CT scanner (Kontich, Belgium) at a resolution of 19.9 mm. Each tooth was positioned on the specimen stage for the scanner by using a silicone mold. Specimens with very wide or oval-shaped root canals were excluded from the study. Following scanning, 30 teeth with regular, round canal cross-sections, and straight root canals were selected. These teeth were stored in distilled water throughout the study.
Preparation and Filling of the Root Canals
The teeth were decoronated to standardize the root lengths to 16 mm. A size 10 K-file (Mani Inc., TochigiKen, Japan) was placed passively in each root canal until it exited through the apical foramen. The working length was set to be 1 mm shorter than the measured length to reach the foramen. ProTaper Universal (PTU) rotary instruments (Dentsply Tulsa Dental Specialties, Tulsa,
OK) were then used according to the manufacturer’s instructions. All canals were prepared to size F1 file and they were irrigated with 2 ml of 5.25% sodium hypochlorite by means of a syringe with a 30-gauge NaviTip irrigation needle (Ultradent, South Jordan, UT) after each instrument. After instrumentation, all root canals were irrigated with 5 ml of 17% EDTA followed by a final rinse with distilled water. The canals were then dried with paper points. The teeth were repositioned in the same silicone molds on the specimen stage and re-scanned using the parameters described below. After scanning, the root canals were filled using the lateral condensation technique with gutta-percha and AHPlus (DeTrey Dentsply, Kontanz, Germany). The access cavities were filled with Cavit-G (3M Espe, Seefeld, Germany) and the teeth were stored at 37˚C with 100% humidity for 1 month. The teeth were then scanned again and the volumes of the root fillings were determined (see below).
Root Canal Re-Treatment Techniques
The teeth were randomly divided into three groups with ten specimens each. All roots had the coronal 3 mm of the root filling material removed by Gates– Glidden drills to create a reservoir for the solvent. In order to soften the root filling material, 0.5 ml eucalyptol oil was introduced in the coronal part of the canal for 30 s before further instrumentation. The gutta-percha and sealer were then removed using the following techniques: Group 1: Size 15 and 20 Hedstro¨m files (Mani Inc., Tochigi-Ken, Japan) were used until they reached the working length. Gutta-percha removal was completed using size 25 files and step-back increments to size 40. Group 2: PTU-R instruments were used. The D1 (size 30, 0.09 taper), D2 (size 25, 0.08 taper), and finally D3 (size 20, 0.07 taper) instruments were used to remove the coronal, middle, and apical thirds of the root canal fillings, respectively. The apical preparation was then completed by using the F2 PTU instrument. The instruments were used with a torque-limited electric motor (Silver RECI˙PROC motor, VDW, Munich, Germany) in the “PTU” mode. Group 3: WaveOne Primary instruments were used. These instruments have a tip size 25 with a 0.08 taper in the apical 3 mm with a subsequent decreasing and variable taper. They were used with a reciprocating gentle in-and-out motion powered by the same torquelimited electric motor used in Group 2 but in the “WAVEONE ALL” mode. A single operator performed all endodontic procedures. Each instrument was used once. The canals were
D. Helvacioglu-Yigit et al.: Instrumentation systems for root filling removal
3
Fig 1. Micro-CT images of a specimen representative of Group 1: (a) three-dimensional reconstruction of the root canal system after filling; (b) cross-sectional scans at 3, 6, and 9 mm from the apical foramen after root canal filling; (c) three-dimensional reconstruction of the same specimen after filling removal; (d) cross-sectional scans at the same cross-sections after filling removal.
Fig 2. Micro-CT images of a specimen representative of Group 2: (a) three-dimensional reconstruction of the root canal system after filling; (b) cross-sectional scans at 3, 6, and 9 mm from the apical foramen after root canal filling; (c) three-dimensional reconstruction of the same specimen after filling removal; (d) cross-sectional scans at the same cross-sections after filling removal.
constantly irrigated with 2.5% NaOCl during root canal re-treatment. The removal of the root filling was judged to be complete when the working length was reached, and no filling material was seen on the instrument when withdrawn from the canal. The operating time in seconds from the start of gutta-percha removal until the end of the re-treatment was recorded. All canals were finally irrigated with NaOCl and dried with paper points. The teeth were re-positioned
into the same molds and a fourth micro-CT scan was performed using the same parameters.
Micro-CT Scans and Volumetric Analysis
A Skyscan 1172 high-resolution micro-CT scanner was used to scan the specimens at four stages (before instrumentation, after instrumentation, after root filling,
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Fig 3. Micro-CT images of a specimen representative of Group 3: (a) three-dimensional reconstruction of the root canal system after filling; (b) cross-sectional scans at 3, 6, and 9 mm from the apical foramen after root canal filling; (c) three-dimensional reconstruction of the same specimen after filling removal; (d) cross-sectional scans at the same cross-sections after filling removal.
and after removing the root filling). The X-ray tube was operated at 80 kV and 128 mA with Al and Cu filters. Samples were scanned at 360˚ rotation with a rotation step of 0.5˚. The image pixel size was 19.9 mm. Two-dimensional images were reconstructed using NRecon software (Kontich, Belgium) (Figs. 1–3). CTan software (Kontich, Belgium) was used for the 3D volumetric analysis. The volume of filling material was calculated using post-threshold-based segmentation. For each specimen, 13 mm length of the root from the apex was analyzed to standardize the length of the specimens as well as to discard the coronal portion of the root canal filling that was removed with the Gates– Glidden drills. The volumes of the root filling material were measured in mm3 before and after removing the materials (Figs. 1–3). The percentage of volume of remaining filling material was calculated using the equation below:
Results Means and standard deviations for the percentage of remaining filling material and the time taken to remove the filling material are summarized in Table I. When the mean percentage of remaining filling material was analyzed, Group 1 had the highest mean percentage (9.74%), whereas Group 2 had the lowest (1.77%). There was a statistically significant difference between Groups 1 and 2 (p ¼ 0.002). However, there were no statistically significant differences between Groups 2 and 3, or between Groups 1 and 3. When the mean time for removal of root filling material was evaluated, Groups 2 and 3 required significantly less time than Group 1 (p < 0.05). However, the difference was not significant between Groups 2 and 3 (p ¼ 0.066).
Volume of remaining filling material after re-treatment Volume of filling material after root filling
100 ¼ %Volume of remaining filling material:
Statistical Analysis
The percentage of residual filling material and the mean time for root filling removal were statistically evaluated by using SPSS software version 15 (SPSS Inc., Chicago, IL). The One-way analysis of variance test was used. Tukey’s post-hoc test was used to compare the groups. The significance level was set at p < 0.05 for all statistical analysis.
TABLE I Means and standard deviations for remaining filling material (%) and the time required to remove filling material (seconds) Group
N
Remaining filling materal (%) SD
Time (seconds) SD
1 2 3
10 10 10
9.74 6.87a 1.77 1.55b 5.47 4.22a,b
661.74 134.79A 273.96 39.42B 183.96 47.41B
Means followed by the same letter were not significantly different (p > 0.05).
D. Helvacioglu-Yigit et al.: Instrumentation systems for root filling removal
Discussion Removal of existing filling materials from root canals is a very important aspect of root canal re-treatment. Any remaining filling material may trap bacteria (especially in the dentin tubules) which are likely to have been responsible for the periapical pathosis leading to the need for further treatment (Keles et al., 2013; Zuolo et al., 2013). Removing as much filling material as possible is also essential for adequate root canal preparation, disinfection, and complete re-filling of the root canal system (Gordon, 2005). Techniques for the removal of root filling materials have been assessed using different methods in previous studies. Some studies have used digital images of longitudinally sectioned roots but this technique could lead to loss of remaining filling material during the sectioning process (Schirrmeister et al., 2006b; Kfir et al., 2012; Zuolo et al., 2013). In addition, and importantly, with this method, the amount of residual filling material could not be compared to the amount of filling material that was initially present. Radiographic examinations have been used as a nondestructive evaluation method, but this provides only 2D information and fails to accurately detect the amount of residual filling material since radiographs may not show very small amounts of residual material (Schirrmeister et al., 2006a; Kfir et al., 2012). Another non-destructive method is to decalcify and clear the teeth, which allows 3D visualization. However, evaluation scales used with this method are subjective (Hulsmann and Bluhm, 2004). In order to overcome this limitation, Schirrmeister et al. (2006b) used image analysis software to measure the residual filling area on the canal wall of the cleared teeth. Micro-CT imaging has also been used to analyse the volume of residual filling material (Hammad et al., 2008; Ma et al., 2012; Rodig et al., 2012). This non-destructive method allows 3D quantitative evaluation and step-by-step analysis by scanning after each stage of the procedure during re-treatment. The only limitation of this method is the difficulty of clearly distinguishing between the gutta percha and the sealer in the residual material. However, this is not a critical issue since the entire root filling (i.e., the core material plus the sealer) ideally needs to be removed to facilitate re-treatment and disinfection of the root canal system. Hence, an overall assessment of the total remaining filling material is sufficent. In the present study, the volume of the root filling prior to removal and the residual filling material were evaluated using micro-CT imaging. This enabled the percentage of remaining filling material to be calculated. Most of the in vitro studies evaluating the efficiency of root canal re-treatment techniques have used straight root canals (Hulsmann and Bluhm, 2004; Schirrmeister et al., 2006a; Gu et al., 2008; Zuolo et al., 2013). In the
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current study, maxillary incisors with straight roots and round canal cross-sections were selected to facilitate the standardization of the specimens. Since under-prepared root canals might be seen in many re-treatment cases, the canals in the present study were originally prepared to working length with an F1 PTU instrument. Therefore, instruments with size 25 tip were used in the re-treatment procedure in all groups. Since the size D3 PTU-R instrument has a size 20 tip, the PTU-R instruments were followed by F2 PTU instruments in Group 2. Using a solvent during root canal re-treatment helps to reduce the working time but has not affected the amount of residual filling material (Hulsmann and Bluhm, 2004). Moreover, one study reported that the softened gutta-percha could be easily compacted into the irregularities of the root canal wall and dentinal tubules, which makes its removal more difficult (Saglam et al., 2013). However, this effect was reduced when using eucalyptol compared with chloroform (Horvath et al., 2009). Eucalyptol has also been found to be safe and efficient when used as a solvent in root canals (Hunter et al., ’91). Therefore, in the present study, a small amount of eucalyptol was used in the coronal third of the canal to soften the filling material and to allow the instruments to penetrate easily. The results of the present study showed that none of the tested re-treatment techniques completely removed the root filling materials which is in accordance with previous studies (Barrieshi-Nusair, 2002; Hulsmann and Bluhm, 2004; Hammad et al., 2008; Marfisi et al., 2010; Kfir et al., 2012; Rodig et al., 2012; Zuolo et al., 2013). Although, there was no statistical difference, the volume of residual filling material after using a reciprocating instrument was greater than after the rotary PTU-R instrument was used. This may be attributed to the brushing motion used with the rotary instruments. The reciprocating motion on the other hand may minimize the torsional stresses and reduce the screwing effect of the instrument (Berutti et al., 2012; Lim et al., 2013) because clockwise and counter-clockwise rotations allow the instrument to cut and consecutively disengage the dentin or root filling material. However, there are only a few studies that have evaluated the effectiveness of reciprocating systems during re-treatment (Zanettini et al., 2008; Kfir et al., 2012; Zuolo et al., 2013). The findings of the current study are consistent with those of Zuolo et al. (2013) who found no statistical difference between reciprocating instruments and manual re-treatment. Further studies with more focus on the effects of reciprocating motion against the filling material are suggested. Using hand files to remove the root canal filling required more time than using the rotary or reciprocating instruments. This result was in agreement with previous studies (Mollo et al., 2012; Zuolo et al., 2013). The WaveOne instrument is made of a special NiTi alloy
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called M-wire, which has the advantages of increased flexibility and resistance to cyclic fatigue. WaveOne instruments have a non-cutting modified guiding tip (Plotino et al., 2012). Despite this non-cutting tip, the WaveOne instruments required less working time when compared to the PTU-R instrument in the present study. However, the difference was not significant. The lack of significant difference may be attributed to its single file concept (Paque et al., 2011). The reciprocating technique was also found to be faster than rotary and hand file techniques for removing root fillings in another study (Zuolo et al., 2013). Under the limitations of the present study, none of the instrumentation techniques could completely remove all root canal filling materials from the root canals. Reciprocating and rotary systems showed similar performances in terms of efficacy and operating time for root filling removal.
References Barrieshi-Nusair KM. 2002. Gutta-percha retreatment: effectiveness of nickel-titanium rotary instruments versus stainless steel hand files. J Endod 28:454–456. Berutti E, Chiandussi G, Paolino DS, et al. 2012. Canal shaping with WaveOne Primary reciprocating files and ProTaper system: a comparative study. J Endod 38:505–509. Cavenago B, COrdinola-Zapata R, Duarte MA, et al. 2014. Efficacy of xylene and passive ultrasonic irrigation on remaining root filling material during retreatment of anatomically complex teeth. Int Endod J. doi: 10.1111/ iej.12253. Giuliani V, Cocchetti R, Pagavino G. 2008. Efficacy of ProTaper Universal retreatment files in removing filling materials during root canal retreatment. J Endod 34:1381–1384. Gordon MP. 2005. The removal of gutta-percha and root canal sealers from root canals. N Z Dent J 101:44–52. Guess GM. 2004. Predictable therma-fil removal technique using the system-B heat source. J Endod 30:61. Gu LS, Ling JQ, Wei X, Huang XY. 2008. Efficacy of ProTaper Universal rotary retreatment system for gutta-percha removal from root canals. Int Endod J 41:288–295. Hammad M, Qualtrough A, Silikas N. 2008. Three-dimensional evaluation of effectiveness of hand and rotary instrumentation for retreatment of canals filled with different materials. J Endod 34:1370–1373. Horvath SD, Altenburger MJ, Naumann M, Wolkewitz M, Schirrmeister JF. 2009. Cleanliness of dentinal tubules following gutta-percha removal with and without solvents: a scanning electron microscopic study. Int Endod J 42:1032– 1038. Hulsmann M, Bluhm V. 2004. Efficacy, cleaning ability and safety of different rotary NiTi instruments in root canal retreatment. Int Endod J 37:468–476. Hunter KR, Doblecki W, Pelleu GB Jr. 1991. Halothane and eucalyptol as alternatives to chloroform for softening guttapercha. J Endod 17:310–311. Keles A, Alcin H, Kamalak A, Versiani MA. 2013. Oval-shaped canal retreatment with self-adjusting file: a micro-computed tomography study. Clin Oral Investig 18:1147–1153. Kfir A, Tsesis I, Yakirevich E, Matalon S, Abramovitz I. 2012. The efficacy of five techniques for removing root filling
material: microscopic versus radiographic evaluation. Int Endod J 45:35–41. Kim HC, Hwang YJ, Jung DW, You SY, Lee W. 2013. Microcomputed tomography and scanning electron microscopy comparisons of two nickel-titanium rotary root canal instruments used with reciprocating motion. Scanning 35:112–118. Lim YJ, Park SJ, Kim HC, Min KS. 2013. Comparison of the centering ability of Wave One and Reciproc nickel-titanium instruments in simulated curved canals. Restor Dent Endod 38:21–25. Ma J, Al-Ashaw AJ, Shen Y, et al. 2012. Efficacy of ProTaper Universal rotary retreatment system for gutta-percha removal from oval root canals: a micro-computed tomography study. J Endod 38:1516–1520. Marfisi K, Mercade M, Plotino G, et al. 2010. Efficacy of three different rotary files to remove gutta-percha and Resilon from root canals. Int Endod J 43:1022–1028. Mollo A, Botti G, Prinicipi Goldoni N, et al. 2012. Efficacy of two Ni-Ti systems and hand files for removing gutta-percha from root canals. Int Endod J 45:1–6. Paque F, Zehnder M, De-Deus G. 2011. Microtomography-based comparison of reciprocating single-file F2 ProTaper technique versus rotary full sequence. J Endod 37:1394–1397. Plotino G, Grande NM, Testarelli L, Gambarini G. 2012. Cyclic fatigue of Reciproc and WaveOne reciprocating instruments. Int Endod J 45:614–618. Rodig T, Hausdorfer T, Konietschke F, et al. 2012. Efficacy of DRaCe 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 45:580–589. Rodig T, Kupis J, Konietschke F, et al. 2014. Comparison of hand and rotary instrumentation for removing gutta-percha from previously treated curved root canals: a microcomputed tomography study. Int Endod J 47:173–182. Roggendorf MJ, Legner M, Ebert J, et al. 2010. Micro-CT evaluation of residual material in canals filled with Activ GP or GuttaFlow following removal with NiTi instruments. Int Endod J 43:200–209. Ruddle CJ. 2004. Nonsurgical endodontic retreatment. J Calif Dent Assoc 32:474–484. Saad AY, Al-Hadlaq SM, Al-Katheeri NH. 2007. Efficacy of two rotary NiTi instruments in the removal of gutta-percha during root canal retreatment. J Endod 33:38–41. Saglam BC, Kocak MM, Turker SA, Kocak S. 2013. Efficacy of different solvents in removing gutta-percha from curved root canals: a micro-computed tomography study. Aust Endod J doi: 10.1111/aej.12041. Schirrmeister JF, Hermanns P, Meyer KM, Goetz F, Hellwig E. 2006a. 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 39:558–565. Schirrmeister JF, Meyer KM, Hermanns P, Altenburger MJ, Wrbas KT. 2006b. Effectiveness of hand and rotary instrumentation for removing a new synthetic polymer-based root canal obturation material (Epiphany) during retreatment. Int Endod J 39:150–156. Solomonov M, Paque F, Kaya S, et al. 2012. Self-adjusting files in retreatment: a high-resolution micro-computed tomography study. J Endod 38:1283–1287. Zanettini PR, Barletta FB, de Mello Rahde N. 2008. In vitro comparison of different reciprocating systems used during endodontic retreatment. Aust Endod J 34:80–85. Zuolo AS, Mello JE Jr, Cunha RS, Zuolo ML, Bueno CE. 2013. Efficacy of reciprocating and rotary techniques for removing filling material during root canal retreatment. Int Endod J 46:947–953.
Efficacy of Reciprocating and Rotary Systems for Removing Root Filling Material: A Micro-Computed Tomography Study D. HELVACIOGLU-YIGIT,1 A. YILMAZ,2 G. KIZILTAS-SENDUR,3,4 O. S. ASLAN,3,4
AND
P. V. ABBOTT5
1
Faculty of Dentistry, Department of Endodontics, Kocaeli University, Kocaeli, Turkey Faculty of Dentistry, Department of Endodontics, Istanbul University, Istanbul, Turkey 3 Faculty of Engineering and Natural Sciences, Department of Mechatronics Engineering, Sabanci University, Istanbul, Turkey 4 Nanotechnology Research and Application Center, Sabanci University, ˙Istanbul, Turkey 5 School of Dentistry, University of Western Australia, Nedlands, Western Australia, Australia 2
Summary: This study aimed to use micro-computed tomography (micro-CT) imaging to evaluate the efficacy of the reciprocating and rotary systems for the removal of root filling materials in comparison with hand files. Thirty maxillary incisor teeth were prepared with ProTaper Universal (PTU) system, filled using cold lateral condensation and randomly divided into three groups of ten teeth each. The root fillings were removed with WaveOne Reciprocating and ProTaper Universal Retreatment (PTU-R) systems and hand files. Micro-CT was used to scan the specimens before and after each treatment step. Percentage of volume of residual root filling was measured. The operating time was recorded. PTU-R instruments yielded better results for removing filling material, even though there was no statistically significant difference between PTU-R and WaveOne groups. Reciprocating and rotary systems showed similar performances in terms of efficacy and operating time for root filling removal. SCANNING 9999:XX–XX, 2014. © 2014 Wiley Periodicals, Inc. Key words: dentistry, imaging, three-dimensional (3D) reconstruction
Introduction The objectives of endodontic re-treatment include complete removal of the existing root filling material to Contract grant sponsor: Kocaeli University Research Fund; Contract grant numbers: HDP 2013-103, 2013-076. Conflicts of interest: None. Address for reprints: Dilek Helvacioglu-Yigit, Faculty of Dentistry, Department of Endodontics, Kocaeli University, Kocaeli, Turkey. E-mail: [email protected], [email protected] Received 21 June 2014; Accepted with revision 1 August 2014 DOI: 10.1002/sca.21157 Published online XX Month Year in Wiley Online Library (wileyonlinelibrary.com).
the apical foramen followed by biomechanical preparation, disinfection, and subsequently re-filling of the root canals (Ruddle, 2004). However, some filling material may remain on the canal walls, which may result in harboring of micro-organisms and less favorable treatment outcomes. Several instrumentation techniques have been described to improve the removal of root fillings. These include manual instrumentation (Kfir et al., 2012; Rodig et al., 2014) ultrasonic preparation (Cavenago et al., 2014), use of heat-carriers (Guess, 2004), and Ni-Ti rotary instruments (Hulsmann and Bluhm, 2004; Saad et al., 2007; Kfir et al., 2012; Mollo et al., 2012; Rodig et al., 2014). Some studies have demonstrated the effective use of specially designed rotary re-treatment instruments (Giuliani et al., 2008; Gu et al., 2008). They have also been reported to be less time-consuming than manual instrumentation (Mollo et al., 2012). One such system, the Protaper Universal Re-treatment system (PTU-R; Dentsply Maillefer, Ballaigues, Switzerland) consists of three files: D1-30/.09, D2-25/.08, and D3-20/.07. The D1 is designed with an active working tip which allows the instrument to penetrate into the filling material. The effectiveness of re-treatment has been evaluated by a variety of techniques in experimental studies: clearing the teeth by demineralization (Gu et al., 2008), radiographic assessment (Mollo et al., 2012), longitudinal sectioning prior to photographic and microscopic analysis (Giuliani et al., 2008; Hulsmann and Bluhm, 2004; Saad et al., 2007; Zuolo et al., 2013), and a combination of these techniques (Kfir et al., 2012). In some re-treatment studies, the precise volume of residual filling material was determined with the use of micro-computed tomography (micro-CT), which allows non-invasive three-dimensional (3D) quantitative evaluation (Hammad et al., 2008; Roggendorf et al., 2010; Ma et al., 2012; Rodig et al., 2012; Solomonov et al., 2012; Saglam et al., 2013; Rodig et al., 2014). Moreover, by allowing observation of the canal during
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the various stages of root canal re-treatment, this method overcomes the limitations of other assessment methods. The WaveOne instruments (Dentsply Maillefer, Ballaigues, Switzerland), manufactured with M-Wire Ni-Ti alloy, were designed to work with a reciprocation action rather than with rotary action (Kim et al., 2013). The efficacy of reciprocation and rotary techniques using Reciproc and Mtwo R instruments (both from VDW, Munich, Germany) for removing root filling materials has been investigated before and concluded that the reciprocating technique and hand instrumentation combined with Gates–Glidden drills removed more filling material than the rotary technique during re-treatment (Zuolo et al., 2013). However, the efficacy of WaveOne instruments in root canal re-treatment has not been yet investigated. Hence, the purpose of the present study was to extend these observations by evaluating the efficacy of other reciprocating and rotary instruments, namely the WaveOne and PTU-R instruments, for the removal of root canal filling material in comparison with hand files using micro-CT imaging. The times taken to remove root filling material were also compared.
Materials and Methods Fifty fully developed maxillary incisors with intact apices were obtained from the collections of the Department of Oral and MaxilloFacial Surgery, Kocaeli University. The teeth were extracted for clinical reasons in accordance with appropriate consent procedures. Teeth which had undergone root canal treatment, or had root caries or restorations were excluded from the study. Teeth were scanned prior to any treatment by using a Skyscan 1172 high-resolution micro-CT scanner (Kontich, Belgium) at a resolution of 19.9 mm. Each tooth was positioned on the specimen stage for the scanner by using a silicone mold. Specimens with very wide or oval-shaped root canals were excluded from the study. Following scanning, 30 teeth with regular, round canal cross-sections, and straight root canals were selected. These teeth were stored in distilled water throughout the study.
Preparation and Filling of the Root Canals
The teeth were decoronated to standardize the root lengths to 16 mm. A size 10 K-file (Mani Inc., TochigiKen, Japan) was placed passively in each root canal until it exited through the apical foramen. The working length was set to be 1 mm shorter than the measured length to reach the foramen. ProTaper Universal (PTU) rotary instruments (Dentsply Tulsa Dental Specialties, Tulsa,
OK) were then used according to the manufacturer’s instructions. All canals were prepared to size F1 file and they were irrigated with 2 ml of 5.25% sodium hypochlorite by means of a syringe with a 30-gauge NaviTip irrigation needle (Ultradent, South Jordan, UT) after each instrument. After instrumentation, all root canals were irrigated with 5 ml of 17% EDTA followed by a final rinse with distilled water. The canals were then dried with paper points. The teeth were repositioned in the same silicone molds on the specimen stage and re-scanned using the parameters described below. After scanning, the root canals were filled using the lateral condensation technique with gutta-percha and AHPlus (DeTrey Dentsply, Kontanz, Germany). The access cavities were filled with Cavit-G (3M Espe, Seefeld, Germany) and the teeth were stored at 37˚C with 100% humidity for 1 month. The teeth were then scanned again and the volumes of the root fillings were determined (see below).
Root Canal Re-Treatment Techniques
The teeth were randomly divided into three groups with ten specimens each. All roots had the coronal 3 mm of the root filling material removed by Gates– Glidden drills to create a reservoir for the solvent. In order to soften the root filling material, 0.5 ml eucalyptol oil was introduced in the coronal part of the canal for 30 s before further instrumentation. The gutta-percha and sealer were then removed using the following techniques: Group 1: Size 15 and 20 Hedstro¨m files (Mani Inc., Tochigi-Ken, Japan) were used until they reached the working length. Gutta-percha removal was completed using size 25 files and step-back increments to size 40. Group 2: PTU-R instruments were used. The D1 (size 30, 0.09 taper), D2 (size 25, 0.08 taper), and finally D3 (size 20, 0.07 taper) instruments were used to remove the coronal, middle, and apical thirds of the root canal fillings, respectively. The apical preparation was then completed by using the F2 PTU instrument. The instruments were used with a torque-limited electric motor (Silver RECI˙PROC motor, VDW, Munich, Germany) in the “PTU” mode. Group 3: WaveOne Primary instruments were used. These instruments have a tip size 25 with a 0.08 taper in the apical 3 mm with a subsequent decreasing and variable taper. They were used with a reciprocating gentle in-and-out motion powered by the same torquelimited electric motor used in Group 2 but in the “WAVEONE ALL” mode. A single operator performed all endodontic procedures. Each instrument was used once. The canals were
D. Helvacioglu-Yigit et al.: Instrumentation systems for root filling removal
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Fig 1. Micro-CT images of a specimen representative of Group 1: (a) three-dimensional reconstruction of the root canal system after filling; (b) cross-sectional scans at 3, 6, and 9 mm from the apical foramen after root canal filling; (c) three-dimensional reconstruction of the same specimen after filling removal; (d) cross-sectional scans at the same cross-sections after filling removal.
Fig 2. Micro-CT images of a specimen representative of Group 2: (a) three-dimensional reconstruction of the root canal system after filling; (b) cross-sectional scans at 3, 6, and 9 mm from the apical foramen after root canal filling; (c) three-dimensional reconstruction of the same specimen after filling removal; (d) cross-sectional scans at the same cross-sections after filling removal.
constantly irrigated with 2.5% NaOCl during root canal re-treatment. The removal of the root filling was judged to be complete when the working length was reached, and no filling material was seen on the instrument when withdrawn from the canal. The operating time in seconds from the start of gutta-percha removal until the end of the re-treatment was recorded. All canals were finally irrigated with NaOCl and dried with paper points. The teeth were re-positioned
into the same molds and a fourth micro-CT scan was performed using the same parameters.
Micro-CT Scans and Volumetric Analysis
A Skyscan 1172 high-resolution micro-CT scanner was used to scan the specimens at four stages (before instrumentation, after instrumentation, after root filling,
SCANNING VOL. 9999, 9999 (2014)
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Fig 3. Micro-CT images of a specimen representative of Group 3: (a) three-dimensional reconstruction of the root canal system after filling; (b) cross-sectional scans at 3, 6, and 9 mm from the apical foramen after root canal filling; (c) three-dimensional reconstruction of the same specimen after filling removal; (d) cross-sectional scans at the same cross-sections after filling removal.
and after removing the root filling). The X-ray tube was operated at 80 kV and 128 mA with Al and Cu filters. Samples were scanned at 360˚ rotation with a rotation step of 0.5˚. The image pixel size was 19.9 mm. Two-dimensional images were reconstructed using NRecon software (Kontich, Belgium) (Figs. 1–3). CTan software (Kontich, Belgium) was used for the 3D volumetric analysis. The volume of filling material was calculated using post-threshold-based segmentation. For each specimen, 13 mm length of the root from the apex was analyzed to standardize the length of the specimens as well as to discard the coronal portion of the root canal filling that was removed with the Gates– Glidden drills. The volumes of the root filling material were measured in mm3 before and after removing the materials (Figs. 1–3). The percentage of volume of remaining filling material was calculated using the equation below:
Results Means and standard deviations for the percentage of remaining filling material and the time taken to remove the filling material are summarized in Table I. When the mean percentage of remaining filling material was analyzed, Group 1 had the highest mean percentage (9.74%), whereas Group 2 had the lowest (1.77%). There was a statistically significant difference between Groups 1 and 2 (p ¼ 0.002). However, there were no statistically significant differences between Groups 2 and 3, or between Groups 1 and 3. When the mean time for removal of root filling material was evaluated, Groups 2 and 3 required significantly less time than Group 1 (p < 0.05). However, the difference was not significant between Groups 2 and 3 (p ¼ 0.066).
Volume of remaining filling material after re-treatment Volume of filling material after root filling
100 ¼ %Volume of remaining filling material:
Statistical Analysis
The percentage of residual filling material and the mean time for root filling removal were statistically evaluated by using SPSS software version 15 (SPSS Inc., Chicago, IL). The One-way analysis of variance test was used. Tukey’s post-hoc test was used to compare the groups. The significance level was set at p < 0.05 for all statistical analysis.
TABLE I Means and standard deviations for remaining filling material (%) and the time required to remove filling material (seconds) Group
N
Remaining filling materal (%) SD
Time (seconds) SD
1 2 3
10 10 10
9.74 6.87a 1.77 1.55b 5.47 4.22a,b
661.74 134.79A 273.96 39.42B 183.96 47.41B
Means followed by the same letter were not significantly different (p > 0.05).
D. Helvacioglu-Yigit et al.: Instrumentation systems for root filling removal
Discussion Removal of existing filling materials from root canals is a very important aspect of root canal re-treatment. Any remaining filling material may trap bacteria (especially in the dentin tubules) which are likely to have been responsible for the periapical pathosis leading to the need for further treatment (Keles et al., 2013; Zuolo et al., 2013). Removing as much filling material as possible is also essential for adequate root canal preparation, disinfection, and complete re-filling of the root canal system (Gordon, 2005). Techniques for the removal of root filling materials have been assessed using different methods in previous studies. Some studies have used digital images of longitudinally sectioned roots but this technique could lead to loss of remaining filling material during the sectioning process (Schirrmeister et al., 2006b; Kfir et al., 2012; Zuolo et al., 2013). In addition, and importantly, with this method, the amount of residual filling material could not be compared to the amount of filling material that was initially present. Radiographic examinations have been used as a nondestructive evaluation method, but this provides only 2D information and fails to accurately detect the amount of residual filling material since radiographs may not show very small amounts of residual material (Schirrmeister et al., 2006a; Kfir et al., 2012). Another non-destructive method is to decalcify and clear the teeth, which allows 3D visualization. However, evaluation scales used with this method are subjective (Hulsmann and Bluhm, 2004). In order to overcome this limitation, Schirrmeister et al. (2006b) used image analysis software to measure the residual filling area on the canal wall of the cleared teeth. Micro-CT imaging has also been used to analyse the volume of residual filling material (Hammad et al., 2008; Ma et al., 2012; Rodig et al., 2012). This non-destructive method allows 3D quantitative evaluation and step-by-step analysis by scanning after each stage of the procedure during re-treatment. The only limitation of this method is the difficulty of clearly distinguishing between the gutta percha and the sealer in the residual material. However, this is not a critical issue since the entire root filling (i.e., the core material plus the sealer) ideally needs to be removed to facilitate re-treatment and disinfection of the root canal system. Hence, an overall assessment of the total remaining filling material is sufficent. In the present study, the volume of the root filling prior to removal and the residual filling material were evaluated using micro-CT imaging. This enabled the percentage of remaining filling material to be calculated. Most of the in vitro studies evaluating the efficiency of root canal re-treatment techniques have used straight root canals (Hulsmann and Bluhm, 2004; Schirrmeister et al., 2006a; Gu et al., 2008; Zuolo et al., 2013). In the
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current study, maxillary incisors with straight roots and round canal cross-sections were selected to facilitate the standardization of the specimens. Since under-prepared root canals might be seen in many re-treatment cases, the canals in the present study were originally prepared to working length with an F1 PTU instrument. Therefore, instruments with size 25 tip were used in the re-treatment procedure in all groups. Since the size D3 PTU-R instrument has a size 20 tip, the PTU-R instruments were followed by F2 PTU instruments in Group 2. Using a solvent during root canal re-treatment helps to reduce the working time but has not affected the amount of residual filling material (Hulsmann and Bluhm, 2004). Moreover, one study reported that the softened gutta-percha could be easily compacted into the irregularities of the root canal wall and dentinal tubules, which makes its removal more difficult (Saglam et al., 2013). However, this effect was reduced when using eucalyptol compared with chloroform (Horvath et al., 2009). Eucalyptol has also been found to be safe and efficient when used as a solvent in root canals (Hunter et al., ’91). Therefore, in the present study, a small amount of eucalyptol was used in the coronal third of the canal to soften the filling material and to allow the instruments to penetrate easily. The results of the present study showed that none of the tested re-treatment techniques completely removed the root filling materials which is in accordance with previous studies (Barrieshi-Nusair, 2002; Hulsmann and Bluhm, 2004; Hammad et al., 2008; Marfisi et al., 2010; Kfir et al., 2012; Rodig et al., 2012; Zuolo et al., 2013). Although, there was no statistical difference, the volume of residual filling material after using a reciprocating instrument was greater than after the rotary PTU-R instrument was used. This may be attributed to the brushing motion used with the rotary instruments. The reciprocating motion on the other hand may minimize the torsional stresses and reduce the screwing effect of the instrument (Berutti et al., 2012; Lim et al., 2013) because clockwise and counter-clockwise rotations allow the instrument to cut and consecutively disengage the dentin or root filling material. However, there are only a few studies that have evaluated the effectiveness of reciprocating systems during re-treatment (Zanettini et al., 2008; Kfir et al., 2012; Zuolo et al., 2013). The findings of the current study are consistent with those of Zuolo et al. (2013) who found no statistical difference between reciprocating instruments and manual re-treatment. Further studies with more focus on the effects of reciprocating motion against the filling material are suggested. Using hand files to remove the root canal filling required more time than using the rotary or reciprocating instruments. This result was in agreement with previous studies (Mollo et al., 2012; Zuolo et al., 2013). The WaveOne instrument is made of a special NiTi alloy
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called M-wire, which has the advantages of increased flexibility and resistance to cyclic fatigue. WaveOne instruments have a non-cutting modified guiding tip (Plotino et al., 2012). Despite this non-cutting tip, the WaveOne instruments required less working time when compared to the PTU-R instrument in the present study. However, the difference was not significant. The lack of significant difference may be attributed to its single file concept (Paque et al., 2011). The reciprocating technique was also found to be faster than rotary and hand file techniques for removing root fillings in another study (Zuolo et al., 2013). Under the limitations of the present study, none of the instrumentation techniques could completely remove all root canal filling materials from the root canals. Reciprocating and rotary systems showed similar performances in terms of efficacy and operating time for root filling removal.
References Barrieshi-Nusair KM. 2002. Gutta-percha retreatment: effectiveness of nickel-titanium rotary instruments versus stainless steel hand files. J Endod 28:454–456. Berutti E, Chiandussi G, Paolino DS, et al. 2012. Canal shaping with WaveOne Primary reciprocating files and ProTaper system: a comparative study. J Endod 38:505–509. Cavenago B, COrdinola-Zapata R, Duarte MA, et al. 2014. Efficacy of xylene and passive ultrasonic irrigation on remaining root filling material during retreatment of anatomically complex teeth. Int Endod J. doi: 10.1111/ iej.12253. Giuliani V, Cocchetti R, Pagavino G. 2008. Efficacy of ProTaper Universal retreatment files in removing filling materials during root canal retreatment. J Endod 34:1381–1384. Gordon MP. 2005. The removal of gutta-percha and root canal sealers from root canals. N Z Dent J 101:44–52. Guess GM. 2004. Predictable therma-fil removal technique using the system-B heat source. J Endod 30:61. Gu LS, Ling JQ, Wei X, Huang XY. 2008. Efficacy of ProTaper Universal rotary retreatment system for gutta-percha removal from root canals. Int Endod J 41:288–295. Hammad M, Qualtrough A, Silikas N. 2008. Three-dimensional evaluation of effectiveness of hand and rotary instrumentation for retreatment of canals filled with different materials. J Endod 34:1370–1373. Horvath SD, Altenburger MJ, Naumann M, Wolkewitz M, Schirrmeister JF. 2009. Cleanliness of dentinal tubules following gutta-percha removal with and without solvents: a scanning electron microscopic study. Int Endod J 42:1032– 1038. Hulsmann M, Bluhm V. 2004. Efficacy, cleaning ability and safety of different rotary NiTi instruments in root canal retreatment. Int Endod J 37:468–476. Hunter KR, Doblecki W, Pelleu GB Jr. 1991. Halothane and eucalyptol as alternatives to chloroform for softening guttapercha. J Endod 17:310–311. Keles A, Alcin H, Kamalak A, Versiani MA. 2013. Oval-shaped canal retreatment with self-adjusting file: a micro-computed tomography study. Clin Oral Investig 18:1147–1153. Kfir A, Tsesis I, Yakirevich E, Matalon S, Abramovitz I. 2012. The efficacy of five techniques for removing root filling
material: microscopic versus radiographic evaluation. Int Endod J 45:35–41. Kim HC, Hwang YJ, Jung DW, You SY, Lee W. 2013. Microcomputed tomography and scanning electron microscopy comparisons of two nickel-titanium rotary root canal instruments used with reciprocating motion. Scanning 35:112–118. Lim YJ, Park SJ, Kim HC, Min KS. 2013. Comparison of the centering ability of Wave One and Reciproc nickel-titanium instruments in simulated curved canals. Restor Dent Endod 38:21–25. Ma J, Al-Ashaw AJ, Shen Y, et al. 2012. Efficacy of ProTaper Universal rotary retreatment system for gutta-percha removal from oval root canals: a micro-computed tomography study. J Endod 38:1516–1520. Marfisi K, Mercade M, Plotino G, et al. 2010. Efficacy of three different rotary files to remove gutta-percha and Resilon from root canals. Int Endod J 43:1022–1028. Mollo A, Botti G, Prinicipi Goldoni N, et al. 2012. Efficacy of two Ni-Ti systems and hand files for removing gutta-percha from root canals. Int Endod J 45:1–6. Paque F, Zehnder M, De-Deus G. 2011. Microtomography-based comparison of reciprocating single-file F2 ProTaper technique versus rotary full sequence. J Endod 37:1394–1397. Plotino G, Grande NM, Testarelli L, Gambarini G. 2012. Cyclic fatigue of Reciproc and WaveOne reciprocating instruments. Int Endod J 45:614–618. Rodig T, Hausdorfer T, Konietschke F, et al. 2012. Efficacy of DRaCe 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 45:580–589. Rodig T, Kupis J, Konietschke F, et al. 2014. Comparison of hand and rotary instrumentation for removing gutta-percha from previously treated curved root canals: a microcomputed tomography study. Int Endod J 47:173–182. Roggendorf MJ, Legner M, Ebert J, et al. 2010. Micro-CT evaluation of residual material in canals filled with Activ GP or GuttaFlow following removal with NiTi instruments. Int Endod J 43:200–209. Ruddle CJ. 2004. Nonsurgical endodontic retreatment. J Calif Dent Assoc 32:474–484. Saad AY, Al-Hadlaq SM, Al-Katheeri NH. 2007. Efficacy of two rotary NiTi instruments in the removal of gutta-percha during root canal retreatment. J Endod 33:38–41. Saglam BC, Kocak MM, Turker SA, Kocak S. 2013. Efficacy of different solvents in removing gutta-percha from curved root canals: a micro-computed tomography study. Aust Endod J doi: 10.1111/aej.12041. Schirrmeister JF, Hermanns P, Meyer KM, Goetz F, Hellwig E. 2006a. 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 39:558–565. Schirrmeister JF, Meyer KM, Hermanns P, Altenburger MJ, Wrbas KT. 2006b. Effectiveness of hand and rotary instrumentation for removing a new synthetic polymer-based root canal obturation material (Epiphany) during retreatment. Int Endod J 39:150–156. Solomonov M, Paque F, Kaya S, et al. 2012. Self-adjusting files in retreatment: a high-resolution micro-computed tomography study. J Endod 38:1283–1287. Zanettini PR, Barletta FB, de Mello Rahde N. 2008. In vitro comparison of different reciprocating systems used during endodontic retreatment. Aust Endod J 34:80–85. Zuolo AS, Mello JE Jr, Cunha RS, Zuolo ML, Bueno CE. 2013. Efficacy of reciprocating and rotary techniques for removing filling material during root canal retreatment. Int Endod J 46:947–953.
