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 Table of Contents  
ORIGINAL ARTICLE
Year : 2020  |  Volume : 4  |  Issue : 1  |  Page : 41-47

Comparative evaluation of incidence of separation of three different endodontic reciprocating files (manufactured from Ni-Ti) using scanning electron microscope: An in vitro study


Department of Conservative and Endodontics, Peoples Dental Academy, Bhopal, Madhya Pradesh, India

Date of Submission13-Jun-2020
Date of Decision06-Jul-2020
Date of Acceptance10-Jul-2020
Date of Web Publication28-Jul-2020

Correspondence Address:
Dr. Purva Jain
Peoples Dental Academy, Bhopal, Madhya Pradesh
India
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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/sidj.sidj_24_20

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  Abstract 

Background and Objectives: The most significant objective of this in vitro study was to analyze the incidence of separation of three different endodontic Ni-Ti manufactured files using a scanning electron microscope (SEM) used in root canal shaping.
Materials and Methods: Freshly extracted teeth (maxillary 1st molars and mandibular 1st molars) were obtained from the Department of Oral and Maxillofacial Surgery, People's Dental Academy, Bhopal, India, and selected for root canal shaping with Ni-Ti manufactured three types of endodontic file. Ninety canals determined for root canal shaping with three different endodontic files were divided into three equal groups (WaveOne, Reciproc instruments, and WaveOne Gold during biomechanical preparation) to know the number of canals prepared before separation (i.e., lifespan). The data were recorded using a SEM and analyzed using analysis of variance, followed by Tukey's post hoc test.
Results: The mean score between the three files used was for the WaveOne file system was 5.40 ± 0.89, for Reciproc file system was 5.90 ± 1.19, and for WaveOne Gold file was 9.33 ± 1.58. Statistically, it shows a significant difference in the mean number of canals prepared before separation among three file systems (F = 87.46, P < 0.001). Further, the mean number of canals prepared before the separation of WaveOne Gold file was found to be significantly (P < 0.001) different and higher as compared to both WaveOne and Reciproc files.
Conclusion: According to the outcome of this in vitro study, the longest existence span was found in WaveOne Gold file system, accompanied by Reciproc file, and WaveOne file was found with the shortest existence span.

Keywords: Endodontic files, Ni-Ti files, Reciproc, scanning electron microscope, WaveOne Gold


How to cite this article:
Jain P, Tyagi S, Mahendra M, Dwivedi V, Singh P, Khan S, Luhana R, Gupta A. Comparative evaluation of incidence of separation of three different endodontic reciprocating files (manufactured from Ni-Ti) using scanning electron microscope: An in vitro study. Saint Int Dent J 2020;4:41-7

How to cite this URL:
Jain P, Tyagi S, Mahendra M, Dwivedi V, Singh P, Khan S, Luhana R, Gupta A. Comparative evaluation of incidence of separation of three different endodontic reciprocating files (manufactured from Ni-Ti) using scanning electron microscope: An in vitro study. Saint Int Dent J [serial online] 2020 [cited 2020 Aug 8];4:41-7. Available from: http://www.sidj.org/text.asp?2020/4/1/41/291031


  Introduction Top


Endodontics is currently one of the most varied categories in dentistry today. Dentists are constantly in search of upgrades and improvements OF emerging new techniques and protocols, with the modern instrument and latest technologies available now. The choice in the line of treatment and by default, the instruments to be utilized need to be sterilized and disinfect by proper method.[1] Endodontic treatment is intended to prevent, control, and treat infections of pulp and periapical pathologies. Due to the role of microorganisms in the growth of periradicular lesions, it is evident that the outcome of endodontic treatment relies on microorganism elimination.[2] Thus, elimination of bacteria from the root canal is among the primary targets of endodontic treatment.[2],[3],[4] Shaping the root canal to a tapered funnel shape fulfills the biological requirement for proper irrigation to get bacteria and pulp tissue-free root canal,[5] it also provides the appropriate shape for obturating materials in three-dimensional obturation.[5],[6],[7]

Ni-Ti manufactured rotary instruments are widely used for root canal therapy because of its high flexibility and cutting efficiency.[8],[9],[10] The instrument placed in the middle of the canal has rendered it easier to create a more rounded and tapered funnel-shaped preparation, thereby reducing the incidence of procedural mishaps such as transportation, zipping, and ledge.[11],[12] With these benefits, few concerns that Ni-Ti manufactured files display unexplained breakage and high cost.[9],[13] A recent retrospective study[14] showed that file separation occurred in curved canals, like mandibular molar teeth.

Single-use, the single-file reciprocating system has increased prospects for the preparation of root canals.[15],[16] The learning curve of these systems and the cost efficiency compared to other rotary systems with multiple instruments are becoming more attractive due to their simple technique and a single instrument to prepare the root canal.[17] This movement disengages the file from dentin before it locks in the canal and reduces the risk of root canal deformation and instrument separation.[18],[19],[20],[21],[22] Hence, the aim of thisin vitro study was to analyze the incidence of separation of three different endodontic files using a scanning electron microscope (SEM) used in root canal shaping.


  Materials and Methods Top


Sample collections

The study was conducted at People's Dental Academy Madya Pradesh India with approval of the Institutional Ethical Committee (Reference No. PDA/dean/17/159). Freshly extracted Maxillary and mandibular first molar teeth obtained from the Department of Oral and Maxillofacial Surgery, People's Dental Academy were washed up under tap water to render them form blood and saliva. Calculus and soft-tissue debris were cleaned by ultrasonic scaler and were then stored in specimen bottles filled with purified filtered water.

Inclusion criteria includes 90 canals were assigned in three equal groups determined from a group of extracted teeth and were selected for root canal shaping with Ni-Ti Manufactured three different endodontic file WaveOne (Dentsply Maillefer), WaveOne GOLD (Ballaigues, Switzerland), and Reciproc (VDW, Germany).

Exclusion Criteria involve hypoplastic teeth, calcified/canal blockage, endodontically treated teeth/teeth with restorations, teeth with periapical pathology, or any other abnormality, teeth with internal resorption, fractured teeth, and carious teeth.

Preparation of the sample

Buccal canals of extracted maxillary molars and mesial canals of extracted mandibular molars, which were small and tortuous, were used for this study. Access cavities were prepared, and the working lengths were determined as follows [Figure 1]:
Figure 1: Showing access cavity preparation, Biomechanical preparation and working length determination

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A #10 k-file was inserted into the root canal until the tip of the file flushed with apical foramen. From that point, 1 mm was subtracted, and the length was defined as the working length of the root canal. After working length is determined, a glide path was produced using #15 k–file [Figure 1]. After the glide path was performed through a size 15 k type File, the teeth were prepared using the three different endodontic reciprocating file systems. Biomechanical preparation of the canal was done in a crown down fashion with the help of an endodontic motor. All the selected ninety canals were divided into three equal categories, according to the system used for the biomechanical preparation of the root canal: Group I (n = 30 canals) - Root canal preparation with WaveOne file.(Dentsply Maillefer, Ballaigues, Switzerland) [Figure 2], Group II (n = 30 canals) - Root canal preparation with Reciproc file (VDW, Munich, Germany) [Figure 2], and Group III (n = 30 canals) - Root canal preparation with WaveOne GOLD file (Dentsply Maillefer, Ballaigues, Switzerland) [Figure 2].
Figure 2: Group A – Root canal preparation with Wave One File, Group B – Root canal preparation with Reciproc File and Group C – Root canal preparation with Waveone Gold File respectively

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Irrigation was done with 3% sodium hypochlorite, following the change of every instrument. A final flush of 2 mL 17% EDTA (pH = 7.7) was applied for 3 min to eliminate the smear layer. Then, the canals were washed with 5 mL saline solution and dried with paper points (DENTSPLY Maillefer)

The files of the WaveOne file system, Reciproc file system, and WaveOne Gold file system were used as per the manufacturer's protocol. Every endodontic reciprocating file system was used for root shaping in each group on 90 randomly selected canals from buccal canals of maxillary molars or mesial canals of mandibular molars. The instruments were inspected for separation using a SEM at ×1000 [Figure 2] and [Figure 3].
Figure 3: Root canal preparation with Reciproc file using X-smart plus and Root canal preparation with Reciproc file using X-smart plus

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Statistical analysis was done using Statistical Package of Social Science (SPSS Version 22.0; Chicago Inc., USA). The recorded data were summarized in mean ± standard deviation and compared by one-way analysis of variance (ANOVA) and the significance of mean difference between the groups was done by Tukey's honestly significant difference post hoc test. A two-tailed (α = 2) P < 0.05 was considered statistically significant.


  Results Top


The distribution of study samples was according to three different endodontic reciprocating files manufactured from Ni-Ti was used for root canal shaping in root canal treatment. Samples from the study involve a total of 90 separated (fractured) endodontic reciprocating files during biomechanical preparation of buccal canals of maxillary molars and mesial canals of mandibular molars.

[Table 1] and [Graph 1] reveals a comparative evaluation of the mean number of canals prepared before separating three different endodontic reciprocating single-file systems (i.e., average lifespan). Mean number of canals prepared before fracture of WaveOne file system was 5.40 ± 0.89, by Reciproc file system was 5.90 ± 1.19, and by WaveOne Gold file was 9.33 ± 1.58. The longest lifespan was found in WaveOne Gold file system, followed by Reciproc file, and the shortest lifespan was found in WaveOne file (WaveOne < Reciproc < WaveOne Gold). Comparing the mean number of canals prepared before the separation between three different endodontic reciprocating singlefile systems, ANOVA showed a significantly different number of canals prepared before separation among the files (F = 87.46, P < 0.001) [Table 2].

Table 1: Comparative evaluation of mean number of canals prepared before separation of three different Endodontic reciprocating single file systems

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Table 2: Comparison of difference in mean number of canals prepared before separation between groups by Tukey test

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Further, comparing the difference in mean number of canals prepared before the separation between the files [Table 2] and Graph 2], Tukey test showed significantly (P < 0.001) different and the higher number of canals prepared before separation in WaveOne Gold file as compared to both WaveOne and Reciproc files. However, it did not differ significantly (P > 0.05) between WaveOne and Reciproc files, i.e., found to be statistically the same [Graph 3].



Scanning electron microscopic analysis

The scanning electron analysis of the separated instruments showed the following results: The SEM analysis of the WaveOne file showed flexural fatigue as the predominant mode of separation at 1000× [Figure 4]. The SEM images and analysis of the Reciproc file showed flexural fatigue (Cracks, fatigue striations, and Voids) as the predominant mode of separation at 1000×. The SEM analysis of the WaveOne GOLD file showed torsional fatigue as the predominant mode of separation at 1000×. Fractured surface of the file is showing torsional fatigue (central defects, concentric striations, and dimples) [Figure 5].
Figure 4: Scanning electron microscope

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Figure 5: Separation endodontic file scanning electron microscopy image (central defects, concentric striations and dimples)

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  Discussion Top


Canal preparation is one of the essential steps in treating necrotic and vital dental pulps. This is essential because canal preparation affects the efficacy of all subsequent procedures and includes mechanical debridement, creation of space for irrigation, and optimized canal shape for proper obturation. The introduction of Ni-Ti rotary instruments in 1988 by Walia et al.[10] has profoundly improved the quality of cleaning and shaping root canals. They are flexible (superelasticity), have increased cutting efficiency, and are time-saving. Unexpected fracture of the instrument due to cyclic fatigue (either torsional or flexural) during root canal preparation is one of the significant drawbacks in the use of Ni-Ti manufactured files.

Recently, two different reciprocating systems were introduced: Reciproc (VDW, Munich, Germany) and WaveOne (Dentsply, Maillefer) in which the Waveone files are used with Waveone all mode which has different angles of rotation WaveOne all” mode which has different angles of rotation 170° counterclockwise and then 50° clockwise rotations with 350 rpm. Rate and type of rotation can affect the resistance to fatigue.[21],[22]

Reciproc (VDW, Munich, Germany) endodontic file a Ni-Ti system with an S-shaped cross-section with cutting edges that shapes the canal by reciprocal movement in a 150° counterclockwise and 30° clockwise rotation. The reciprocating instrument first turns in a cutting direction, and then the instrument reverses to release. The file is made from a nickel-titanium-based M wire subjected to a special heat treatment.[22]

According to Berutti et al.,[18] the life-span of a file is “directly proportional” to the stress accumulated during preparation in the root canal. Yared[19] stated that theoretically, the clockwise and counterclockwise movements decrease the occurrence of torsional separation by taper lock. The first objective of the present study was to analyze the clinical performance of the files by evaluating the number of canals prepared by each file before breakage. During the root canal preparation, two or more rotary Ni-Ti files have been used according to the sequence or in combination according to their shaping characteristics. When using a series of nickel-titanium files, few files bear more stress than others. As a result, it is impossible to measure the lifespan of a single file that reaches the WL with the completion of the root canal preparation. Apart from discarding the file when it is deformed or when the clinician is insecure about the state of the file, there is no literature on the incidence of separation of certain types of Ni-Ti files.

According to Iqbal et al.,[14] the chances of file separation is more in molars, especially in mesial canals of mandibular molars. The present study used mesial canals of first mandibular molars and buccal canals of first maxillary molars as specimens. Pruett et al.[9] observed that severe root curvatures increase the chances of instrument separation as there will be greater cyclic fatigue. The present study used canals with <25 curvatures as the specimens.

In this study conducted, mesial canals of first mandibular molars and buccal canals of first maxillary molars with a working length ratio between 19.5 and 20 mm and <25 curvature degrees were prepared using single file Ni-Ti reciprocating system, Waveone Gold, Waveone, and Reciproc. They were selected because they are single-file techniques, with nonworking tip and variable cross-sections along the blade of the instrument. The size of the tip of the instruments used differs; we strictly followed the manufacturer's instruction of WaveOne to use the small WaveOne file, if #10 hands K-file does not quickly move toward the terminus of the canal. The same technique was applied while working with WaveOne Gold and Reciproc (R25) files.[23]

In our study, we compared the average lifespan of the three file systems, and the results obtained were [Table 1] and [Graph 1] and 9.33 ± 1.583 for WaveOne Gold files. No study was found in the literature that determines the lifespan of the WaveOne Gold files. The lifespan obtained for Reciproc files was 5.90 ± 1.185, while Bürklein et al.[20] showed that a single-use Reciproc R25 instrument could be safely used in 4 root canals without fracture, Gavini et al.[21] reported that Reciproc file could resist 1787.78 cycles on average, the double than usual, in reciprocating motion before fracture. Park et al.[22] and Caballero et al.[23] concluded that the Reciproc files could be used in 5 or 9 root canals, respectively, without causing anatomical deformities. According to our study, results obtained were 5.40 ± 0.894 canals for WaveOne files, showing high difference when compared to the study by Karova et al.,[24] which was 17.50 ± 2.12 canals, respectively. In this study, a single Reciproc R25 showed an average lifespan of 5.90 canals.

According to our study, 30 WaveOne GOLD files prepared on average 260 canals, followed by Reciproc files, which prepared 207canals and WaveOne file, which prepared 260 canals in total, respectively. WaveOne Gold files showed the longest lifespan compared to other file systems. There is no study given in the literature to determine the number of root canals prepared by the three systems used in our study. However, from the findings of the present study, the Reciproc files reported a more significant number of canal preparation and less instrument separation when compared to the WaveOne files. WaveOne GOLD still showed better physical properties compared to the other two systems in our study because of its metallurgical improvements in gold wire heat treatment as it increases the elasticity of the file in accordance to a study by Elsaka et al.[25]

Pedullà et al.[26] and Gambarini et al.[27] reported that Reciproc and WaveOne files are commercialized as single-use files. However, in treating multi-rooted cases, each file could work even on 3–4 canals at least and this multiple uses of the same file generate an accumulation of cyclic fatigue as the clinician works from one canal to other, and the study shows resemblance to our study in which usage of each file in multiple canals lead to the separation of files. For the question regarding the lifespan of Ni-Ti rotary files, before discarding them, there is no definite answer. There are several factors to be considered such as complexity and curvature of the root canal system, instrument size, and the action/method of instrumentation. As every clinical case show variability, there is unpredictability in separation and the consequences of separation, a safe number of uses should be provided by manufacturers and strictly observed by clinicians.

Thus, to prevent the risk of separated files within root canals, all files should be examined after each use. Files showing deformation should be discarded immediately. Manufacturing defects can lead to the separation of even a new file during its first use. Therefore, every file should be examined before using it for preparation. Minor defects, both plastic deformation and manufacturing errors, are not seen with the naked eye, so we recommend that files should be examined under at least 10 × magnifications.


  Conclusion Top


Under the conditions of the present study and within its limitations, the following conclusions can be drawn:

  • WaveOne Gold file system with a safe rotational angle prepared the highest number of canals, followed by the Reciproc system and WaveOne file system
  • The predominant mode of separation in WaveOne Gold files seen in the present study was torsional, Reciproc, and WaveOne file was flexural
  • WaveOne Gold file system showed the highest resistance to fatigue, followed by the Reciproc file system and WaveOne file system.


The three groups showed a significant difference regarding the lifespan of the instruments and the mechanism of separation.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.



 
  References Top

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2.
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Kishen A, Shi Z, Shrestha A, Neoh KG. An investigation on the antibacterial and antibiofilm efficacy of cationic nanoparticulates for root canal disinfection. J Endod 2008;34:1515-20.  Back to cited text no. 4
    
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14.
Iqbal MK, Kohli MR, Kim JS. A retrospective clinical study of incidence of root canal instrument separation in an endodontics graduate program: A Penn Endo data base study. J Endod 2006;32:1048-52.  Back to cited text no. 14
    
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Yared G. Canal preparation using only one Ni-Ti rotary instrument: Preliminary observations. Int Endod J 2008;41:339-44.  Back to cited text no. 15
    
16.
De-Deus G, Barino B, Zamolyi RQ, Souza E, Fonseca A Jr., Fidel S, et al. Suboptimal debridement quality produced by the single-file F2 ProTaper technique in oval-shaped canals. J Endod 2010;36:1897-900.  Back to cited text no. 16
    
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19.
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20.
Bürklein S, Hinschitza K, Dammaschke T, Schäfer E. Shaping ability and cleaning effectiveness of two single-file systems in severely curved root canals of extracted teeth: Reciproc and WaveOne versus Mtwo and ProTaper. Int Endod J 2012;45:449-61.  Back to cited text no. 20
    
21.
Gavini G, Caldeira CL, Akisue E, Candeiro GT, Kawakami DA. Resistance to flexural fatigue of Reciproc R25 files under continuous rotation and reciprocating movement. J Endod 2012;38:684-7.  Back to cited text no. 21
    
22.
Park SK, Kim YJ, Shon WJ, You SY, Moon YM, Kim HC, et al. Clinical efficiency and reusability of the reciprocating nickel-titanium instruments according to the root canal anatomy. Scanning 2014;36:246-51.  Back to cited text no. 22
    
23.
Caballero H, Rivera F, Salas H. Scanning electron microscopy of superficial defects in Twisted files and Reciproc nickel-titanium files after use in extracted molars. Int Endod J 2015;48:229-35.  Back to cited text no. 23
    
24.
Karova E, Topalova-Pirinska S. The influence of a glide path on the lifespan of WaveOne reciprocating files. Int J Dent Sci Res 2014;2:59-62.  Back to cited text no. 24
    
25.
Elsaka SE, Elnaghy AM, Badr AE. Torsional and bending resistance of WaveOne gold, reciproc and twisted file adaptive instruments. Int Endod J 2017;50:1077-83.  Back to cited text no. 25
    
26.
Pedullà E, Grande NM, Plotino G, Gambarini G, Rapisarda E. Influence of continuous or reciprocating motion on cyclic fatigue resistance of 4 different nickel-titanium rotary instruments. J Endod 2013;39:258-61.  Back to cited text no. 26
    
27.
Gambarini G, Gergi R, Naaman A, Osta N, Al Sudani D. Cyclic fatigue analysis of twisted file rotary NiTi instruments used in reciprocating motion. Int Endod J 2012;45:802-6.  Back to cited text no. 27
    


    Figures

  [Figure 1], [Figure 2], [Figure 3], [Figure 4], [Figure 5]
 
 
    Tables

  [Table 1], [Table 2]



 

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