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 Table of Contents  
ORIGINAL ARTICLE
Year : 2017  |  Volume : 29  |  Issue : 1  |  Page : 60-64

Comparison of efficacy of hand and rotary instrumentation for removing a resin-based obturating material (EndoRez) in curved root canals during retreatment: An in vitro study


1 Private Practitioner, Al Hilal Hospital, Bahrain
2 Department of Conservative Dentistry and Endodontics, I.T.S Centre for Dental Studies and Research, Ghaziabad, Uttar Pradesh, India

Date of Web Publication25-May-2017

Correspondence Address:
Sonali Taneja
Department of Conservative Dentistry and Endodontics, ITS-CDSR, Muradnagar, Ghaziabad - 201 206, Uttar Pradesh
India
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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/endo.endo_12_17

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  Abstract 

Aim: This study aims to evaluate and compare the efficacy of three rotary NiTi (ProTaper UR, R-Endo, and MTwo R) and one manual (Hedstrom file) instrument in the removal of a resin-based root canal obturation material (EndoRez) during root canal retreatment of curved root canals by area and volumetric analysis.
Methodology: Forty single-rooted curved (10°–30°) human mandibular premolars were decoronated to obtain a standardized working length. The canals were prepared using hand ProTaper instruments and obturated using EndoRez sealer and EndoRez Gutta-percha points. Pretreatment volume analysis of the obturation material was carried out using cone beam computed tomography (CBCT). Samples were divided into four groups (n = 10): Group I - Hedstrom files, Group II - ProTaper UR files, Group III - R-Endo files, and Group IV - MTwo R files. Total time required to attain the working length (T1) and complete removal of material with the last instrument used (T2) was recorded in seconds. Area and volume fractions of remaining filling were calculated in percentage using AUTOCAD 2000 software and CBCT.
Statistical Analysis Used: The results were statistically analyzed using analysis of variance and post hoc tests (Tukey-HSD).
Results: H-files took maximum amount of time for the entire retreatment procedure followed by ProTaper UR, R-Endo, and MTwo R with statistically significant difference. ProTaper UR files showed maximum cleaning efficiency (both in terms of area and volume of the remaining filling material) followed by R-Endo, MTwo R, and H-files with statistically significant difference.
Conclusion: NiTi rotary instruments showed superior performance than hand instruments during retreatment.

Keywords: AutoCAD, cone beam computed tomography, EndoRez, H-files, Mtwo retreatment files, ProTaper universal retreatment files, R-Endo files


How to cite this article:
Malhotra K, Taneja S, Kumar P. Comparison of efficacy of hand and rotary instrumentation for removing a resin-based obturating material (EndoRez) in curved root canals during retreatment: An in vitro study. Endodontology 2017;29:60-4

How to cite this URL:
Malhotra K, Taneja S, Kumar P. Comparison of efficacy of hand and rotary instrumentation for removing a resin-based obturating material (EndoRez) in curved root canals during retreatment: An in vitro study. Endodontology [serial online] 2017 [cited 2019 May 25];29:60-4. Available from: http://www.endodontologyonweb.org/text.asp?2017/29/1/60/206999


  Introduction Top


The success rate of root canal therapy varies between 86% and 98%.[1],[2] When confronted with the endodontic failure, clinicians must know how to select the best, most predictable treatment approach that will provide a long-term success. Over the years, nonsurgical endodontic retreatment has replaced apical surgery for treating endodontically failed cases.

Ideally, during retreatment, the obturating material should be removed adequately so that irrigants and intracanal medicaments should effectively gain access to the complexities of the canal. Most commonly used obturating material is Gutta-percha (GP). However, with the advent of bonding technologies, resin-coated GP and sealers have introduced into the market. EndoRez (Ultradent Inc., South Jordan, UT) is an example of UDMA-based resin sealer used with a resin-coated GP cone for canal obturation. Resin-based obturation system which has proved to be a viable alternative to GP as it has better biocompatibility, reinforces instrumented roots to vertical fracture and increases resistance to microleakage.[3],[4]

The techniques used to remove obturating material in nonsurgical endodontic retreatment include hand or rotary instrumentation with or without heat and solvents and/or ultrasound. NiTi rotary instruments are not only effective in root canal shaping but also efficient in removing GP/sealer from curved root canals during endodontic retreatment. R-Endo (Micro-Mega, Besançon, France), ProTaper UR (Dentsply Maillefer, Ballaigues, Switzerland), and Mtwo retreatment files (Sweden and Martin Padova, Italy) are NiTi rotary instruments used for removal of GP.

Various methods have been used to evaluate the efficiency of retreatment instruments in removing obturating material, such as radiography and cleavage of the dental structure. Barletta and Lagranha (2002),[5] reported a method for analyzing area of the remaining filling material with radiographs being analyzed by means of a software package called AutoCAD 2000. However, this method has limitations as radiographic images provide only two-dimensional (2D) information.

Cone beam computed tomography (CBCT) introduced in endodontic research is a noninvasive method that allows detailed visualization of the morphological features of the root canal, does not require the destruction of the teeth and 3D appraisal of treatments performed within the root canal system.[6]

Till date, no study has reported in the literature that carried out a 3D volumetric evaluation of remaining obturation material after the use of above-mentioned retreatment instruments.

Hence, the aim of this in vitro study was to evaluate and compare the efficacy various hand and rotary NiTi instruments in the removal of a resin-based root canal obturation material (EndoRez) during root canal retreatment through area and volumetric analysis.


  Methodology Top


Forty extracted single-rooted human mandibular premolar teeth with single canal and fully formed apices with 10°–30° curvature were selected. The degree of curvature was evaluated by Schneider's method using AutoCAD software (Autodesk Inc., San Rafael, CA, USA). Standard access cavities were prepared, and an ISO size 15 K-type file was placed into the canal until it was visible at the apical foramen so as to measure the length of the sample. The samples were decoronated to obtain a final dimension of 14 mm. The working length of 13 mm was achieved for each tooth by subtracting 1 mm from the final dimension.

The specimens were then partially embedded into transparent acrylic and were aligned in a manner such that the curvature of roots was in same plane and direction.

The root canals were prepared using Hand ProTaper instruments (Dentsply Maillefer, Ballaigues, Switzerland) with apical preparation till size 25. During instrumentation, the root canals were irrigated with 5 ml of 5% NaOCl and 3 ml of 17% EDTA followed by rinsing with 5 ml of normal saline. Samples were obturated using EndoRez sealer and prefit resin- coated EndoRez GP point of size 25. Lateral compaction was done with resin-coated accessory cones of size 25 (EndoRez) and taper 2%. For establishing immediate coronal seal, the sealer at canal orifice was light cured using QHL 75 (Dentsply-Maillefer, Ballaigues, Switzerland) for 40 s. The samples were then stored at 37°C in 100% humidity for 2 weeks.

Postobturation radiographs and preinstrumentation CBCT scans were done using i-CAT CBCT scanner (Imaging Science International, Hatfield, PA, USA) [Figure 1] and [Figure 2].
Figure 1: Radiographic image of obturation of a sample (before retreatment)

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Figure 2: Cone beam computed tomography scan of obturation of a sample (before retreatment)

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Samples were randomly divided into four groups of ten specimens each according to the type of retreatment instrument used.

In Group I, H-type files with ISO size 25 to ISO size 15 were used in a descending order to the working length using a filing action. Once the working length was reached with a size 15 file, apical instrumentation was done till the file size 25.

In Group II (ProTaper UR), Group III (R-Endo), and Group IV (MTwo R), removal of obturating material was done according to manufacturer's recommended sequence.

During the removal of filling material, root canals were irrigated with 3 ml of 5% NaOCl after each file. The retreatment procedure was assessed as complete when there was no root filling material/sealer covering the instruments and irrigation solution coming out of canal appeared clear of debris.

Evaluation criteria

Time required for removing the obturation material

Total time (including irrigation and change of instrument) required to reach the working length (T1) and complete removal of material with the last instrument used (T2) was recorded in seconds for each sample with the help of a digital stopwatch.

Outcome assessment

Area analysis

The roots were digitally radiographed in buccolingual and mesiodistal directions, and the area of remaining filling material as well as canal wall was calculated in mm 2 using AutoCAD 2000 software (Autodesk Inc, San Rafael, CA, USA) and added [Figure 3].
Figure 3: Area of remaining filling material after retreatment in a sample

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Area fractions of root canal wall covered by remaining filling material (both in mesiodistal and buccolingual canal area) were calculated in percentage terms by dividing the area of remaining filling material with the total area of canal wall. Each image was outlined thrice by the same operator to increase the reproducibility and to decrease the intraoperator variability, and then the average of the obtained measurements was taken.

Volume analysis

Volume analysis was done after obturation, and retreatment was assessed using CBCT and was calculated in mm 3. The volume of remaining filling material was measured by using volume DICOM datasets, and the scans were analyzed on GE advantage Windows software version 4.6. 3D volume rendering of the scans was performed with in vivo 5.2 licensed software (Anatomage, Scan Jose, CA, USA) [Figure 4].
Figure 4: Volume of remaining filling material after retreatment in a sample

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Volume fractions of root canal wall covered by remaining filling material were calculated in percentage terms by dividing the volume of remaining filling material with the volume of the total filling material present in the canal before retreatment.

The results were statistically analyzed using one-way analysis of variance and post hoc tests (Tukey-HSD) using software version SPSS 15 (Chicago, IN, U.S.A).


  Results Top


H-files took maximum amount of time to reach the working length and to remove the entire filling material followed by R-Endo, ProTaper UR, and MTwo R. The difference in the values obtained by all groups was statistically significant (P < 0.05) except between ProTaper UR and R-Endo where statistically similar values were seen to reach working length. ProTaper UR files showed maximum cleaning efficiency among rotary files followed by R-Endo, MTwo R files, and H-files with statistically significant difference among all the groups (P < 0.05) [Table 1].
Table 1: Mean standard deviation of time taken for retreatment and area and volume percentage of remaining filling material by different groups

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  Discussion Top


With significant advancements in the field of endodontics, nonsurgical endodontic retreatment has become the choice of retreatment for failed cases as it is usually less invasive as compared to the surgical procedure. In our study, the root canal retreatment instruments used were R-Endo, ProTaper UR, and Mtwo retreatment files.

In our study during biomechanical preparation, apical preparation was done till size 25 which was same as the tip sizes of two of the instruments used i.e. R-Endo and Mtwo R.[4] Solvents were not used along with retreatment instruments as GP softened by the use of solvents is forced into complex canal anatomy which in turn accentuates the challenge of filling removal.[7]

The results of this study showed that H-files took significantly more time to reach the working length and for complete removal of filling material, in comparison to rotary instruments. This might be because of the greater speed of mechanized instruments.[8],[9] Mittal and Jain reported that hand instruments used along with solvents take shorter time for retreatment when compared to NiTi rotary retreatment instruments.[10] Unal et al. showed contradictory results where H-files took less time for retreatment in comparison to ProTaper UR files and R-Endo files.[11]

MTwo R files took the least amount of time for the entire procedure in comparison to other groups. The reason behind this could be less number of instruments, i.e., R1 (size 25, 0.05 taper) and R2 (size 15, 0.05 taper) and active cutting tip.

Bramante et al. showed contradictory results to our study where ProTaper UR files took lesser retreatment time in comparison to MTwo R. The difference in their and our results might be due to different type of sealers used.[12]

The time taken by ProTaper UR files was significantly less in comparison to R-Endo retreatment files. This might be due to use of lesser number of instruments in Pro Taper UR file system i.e D1, D2 and D3 with sizes - 30, 25 and 20, lengths - 16 mm, 18 mm and 22 mm and tapers - 0.09, 0.07 and 0.06, dedicated to each third of the canal whereas R-Endo NiTi rotary system is available as Re (size 25) to flare the first few millimeters of the canal, and three files R1, R2, and R3 dedicated to each root canal third with tapers 0.08, 0.06, and 0.04.

In our study, ProTaper UR files showed maximum efficacy in comparison to other instruments to remove GP. This may be attributed to their design. D1, D2, and D3 have progressive taper and length that enable the retreatment instruments to cut not only GP but also the superficial layer of dentin during root filling removal. Moreover, the specific flute design and rotary motion of ProTaper UR instruments tend to pull GP into the file flutes and direct it toward the orifice. Furthermore, frictional heat produced during rotary movements plasticize GP that presents less resistance to removal.[13] R-Endo file has noncutting tip, and MTwo R files have single length preparation with single taper which might have led to inferior performance in comparison to ProTaper UR files. Gergi and Sabbagh contradicted our results by reporting that R-Endo files showed similar amount of remaining filling material in comparison to ProTaper UR files. This might be due to the difference in the methodology.[14] Alves et al. reported nonsignificant difference in the percentage of clear area when ProTaper UR and MTwo R files were compared.[15]

De Souza et al. compared the root canal retreatment using reciprocating (Reciproc) and continuous rotary (ProTaper UR) nickel-titanium instrument and reported nonsignificant difference.[16]

Many studies reported better performance of H-files in comparison to ProTaper UR files, which might be due to the difference in apical preparation (size 30) and last ProTaper UR used.[9],[10] Better performance of R-Endo files and MTwo R files in comparison to H-files can be attributed to their design. Some studies reported similar cleaning efficiency of R-Endo and H-files. These findings might be due to the difference in final apical preparation (size 30) and last R-Endo file used.[9]

Various studies reported better performance of H-files in comparison to MTwo R which might be due to the difference in final apical preparation (size 40) and last MTwo R file used. Also, in their study Gates Glidden burs and Xylol was used along with H-files. This might have improved the results obtained after using H-files.[9],[12]

MTwo R files showed inferior performance in comparison to R-Endo files which might be due to single length preparation technique and single taper of MTwo R files which might leave more filling material in the canal during retreatment.

A nonsignificant difference obtained between the area and volume of remaining filling material during quantitative analysis suggests that the remnants of the filling material inside the canal mainly consisted of a film of sealer.


  Conclusion Top


H-files took maximum amount of time for the entire retreatment procedure followed by R-Endo files and ProTaper UR files. MTwo R files took the least amount of time. ProTaper UR files showed maximum cleaning efficiency among rotary files followed by R-Endo and MTwo R files. H-files showed the least cleaning efficiency.

Considering the results of this study, it would be suggested that after the use of retreatment instruments, reinstrumentation of the canal with larger size instrument than the last retreatment instrument used could further reduce the amount of remaining filling material.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.



 
  References Top

1.
Friedman S, Abitbol S, Lawrence HP. Treatment outcome in endodontics: The Toronto Study. Phase 1: Initial treatment. J Endod 2003;29:787-93.  Back to cited text no. 1
    
2.
Friedman S, Mor C. The success of endodontic therapy – Healing and functionality. J Calif Dent Assoc 2004;32:493-503.  Back to cited text no. 2
    
3.
Shipper G, Trope M.In vitro microbial leakage of endodontically treated teeth using new and standard obturation techniques. J Endod 2004;30:154-8.  Back to cited text no. 3
    
4.
Shipper G, Ørstavik D, Teixeira FB, Trope M. An evaluation of microbial leakage in roots filled with a thermoplastic synthetic polymer-based root canal filling material (Resilon). J Endod 2004;30:342-7.  Back to cited text no. 4
    
5.
Barletta FB, Lagranha SB. Comparative analysis of different techniques in root canal retreatment. Endodoncia 2002;20:189-96.  Back to cited text no. 5
    
6.
Marfisi K, Mercade M, Plotino G, Duran-Sindreu F, Bueno R, Roig M. Efficacy of three different rotary files to remove gutta-percha and Resilon from root canals. Int Endod J 2010;43:1022-8.  Back to cited text no. 6
    
7.
Kfir A, Tsesis I, Yakirevich E, Matalon S, Abramovitz I. The efficacy of five techniques for removing root filling material: Microscopic versus radiographic evaluation. Int Endod J 2012;45:35-41.  Back to cited text no. 7
    
8.
Giuliani V, Cocchetti R, Pagavino G. Efficacy of ProTaper universal retreatment files in removing filling materials during root canal retreatment. J Endod 2008;34:1381-4.  Back to cited text no. 8
    
9.
Somma F, Cammarota G, Plotino G, Grande NM, Pameijer CH. The effectiveness of manual and mechanical instrumentation for the retreatment of three different root canal filling materials. J Endod 2008;34:466-9.  Back to cited text no. 9
    
10.
Mittal N, Jain J. Spiral computed tomography assessment of the efficacy of different rotary versus hand retreatment system. J Conserv Dent 2014;17:8-11.  Back to cited text no. 10
[PUBMED]  [Full text]  
11.
Unal GC, Kaya BU, Taç AG, Keçeci AD. A comparison of the efficacy of conventional and new retreatment instruments to remove gutta-percha in curved root canals: An ex vivo study. Int Endod J 2009;42:344-50.  Back to cited text no. 11
    
12.
Bramante CM, Fidelis NS, Assumpção TS, Bernardineli N, Garcia RB, Bramante AS, et al. Heat release, time required, and cleaning ability of MTwo R and ProTaper universal retreatment systems in the removal of filling material. J Endod 2010;36:1870-3.  Back to cited text no. 12
    
13.
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.  Back to cited text no. 13
    
14.
Akpinar KE, Altunbas D, Kustarci A. The efficacy of two rotary NiTi instruments and H-files to remove gutta-percha from root canals. Med Oral Patol Oral Cir Bucal 2012;17:e506-11.  Back to cited text no. 14
    
15.
Alves FR, Ribeiro TO, Moreno JO, Lopes HP. Comparison of the efficacy of nickel-titanium rotary systems with or without the retreatment instruments in the removal of gutta-percha in the apical third. BMC Oral Health 2014;14:102.  Back to cited text no. 15
    
16.
de Souza PF, Oliveira Goncalves LC, Franco Marques AA, Sponchiado Junior EC, Roberti Garcia Lda F, de Carvalho FM. Root canal retreatment using reciprocating and continuous rotary nickel-titanium instruments. Eur J Dent 2015;9:234-9.  Back to cited text no. 16
    


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