| Abstract|| |
Aim and Objective: The aim of this study is to evaluate and compare the effect of one shape, Neolix rotary single-file systems and WaveOne, Reciproc reciprocating single-file systems on pericervical dentin (PCD) using cone-beam computed tomography (CBCT).
Materials and Methods: A total of 40 freshly extracted mandibular premolars were collected and divided into two groups, namely, Group A – Rotary: A1 – Neolix and A2 – OneShape and Group B – Reciprocating: B1 – WaveOne and B2 – Reciproc. Preoperative scans of each were taken followed by conventional access cavity preparation and working length determination with 10-k file. Instrumentation of the canal was done according to the respective file system, and postinstrumentation CBCT scans of teeth were obtained. 90 μm thick slices were obtained 4 mm apical and coronal to the cementoenamel junction. The PCD thickness was calculated as the shortest distance from the canal outline to the closest adjacent root surface, which was measured in four surfaces, i.e., facial, lingual, mesial, and distal for all the groups in the two obtained scans.
Results: There was no significant difference found between rotary single-file systems and reciprocating single-file systems in their effect on PCD, but in Group B2, there was most significant loss of tooth structure in the mesial, lingual, and distal surface (P < 0.05).
Conclusion: Reciproc single-file system removes more PCD as compared to other experimental groups, whereas Neolix single file system had the least effect on PCD.
Keywords: Cone-beam computed tomography; Neolix; Oneshape; pericervical dentin; reciproc; single file system; WaveOne
|How to cite this article:|
Zinge PR, Patil J. Comparative evaluation of effect of rotary and reciprocating single-file systems on pericervical dentin: A cone-beam computed tomography study. J Conserv Dent 2017;20:424-8
|How to cite this URL:|
Zinge PR, Patil J. Comparative evaluation of effect of rotary and reciprocating single-file systems on pericervical dentin: A cone-beam computed tomography study. J Conserv Dent [serial online] 2017 [cited 2021 Sep 17];20:424-8. Available from: https://www.jcd.org.in/text.asp?2017/20/6/424/223187
| Introduction|| |
Successful endodontic treatment depends on the accuracy of diagnosis and adequate mechanical preparation of the pulp space for restoration. The armamentarium of endodontics has grown in complexity over the past 40 years. Different techniques of root canal preparation have been described in the related literature and stainless steel instruments have been used for canal instrumentation.,
Introduction of NiTi rotary instrumentation has revolutionized the art and science of endodontic practice in the few past decade with predictable success. The rotary files have been subjected to constant evaluation in the form of metallurgy, design features, the number of instruments, and the manner in which these instruments are driven (rotary/reciprocation).,
In the bygone decade, several rotary NiTi endodontic file systems have been launched to improve the shaping procedure. However, all these systems recommended the use of a series of files to accomplish the final shape. Recently, the concept of single-file systems has been introduced and is currently being debated for its applicability in contemporary endodontics. The advantages of these single-file systems include a reduction in the working time, prevention of cross-contamination, and improved safety of the shaping procedures. Single-file rotary systems may be classified on the basis of their motion into rotating and reciprocating files.,
It is generally accepted that the removal of excessive amounts of dentin compromises the survival of root-filled teeth and that the strength of endodontically treated teeth is directly related to the amount of remaining sound tooth structure., More recently, the focus is shifting toward the preservation of tooth structure in a cervical portion of the tooth as this portion is considered to be most susceptible to fracture from occlusal forces. The dentin in this critical portion has been called as pericervical dentin (PCD) which extends 4 mm above and below the level of alveolar bone.,,,,, Clark and Khademi stated that peri-cervical dentin (PCD) was shown to be a vital structure responsible for the strength of the tooth.,
There is very limited literature exists to evaluate the effect of rotary single-file systems and reciprocating single-file systems on PCD. Hence, the present study was conducted with an aim to compare and evaluate the effect of rotary and reciprocating single-file instrumentation systems on PCD using cone-beam computed tomography (CBCT).
| Materials and Methods|| |
Forty periodontally involved single-rooted human mandibular premolar teeth, free of caries, cracks, anatomic variations, immature apex, calcifications, resorptions, and restorations were used in the study.
Conservative access preparations were made for all teeth. Each root canal was negotiated by a no 10 K stainless steel file. The working length (WL) was determined for preparation of the canals. A #10 K (DENTSPLY, Maillefer, USA) file was placed in the root canal so that its tip was visible at the apical foramen; the WL was set 1 mm short of the file length. All samples were divided randomly into two categories as Group A: Rotary single-file systems and Group B: Reciprocating single-file systems each containing 20 samples. Group A was again divided into two subgroups Group A1 – One Shape file system (MicroMega, Besancon, France) and A2 – Neolix file system (NEOLIX, Châtres-la-Forêt, France) each containing 10 samples. Group B was also divided into two subgroups Group B1 – WaveOne file system (Dentsply Maillefer, Ballaigues, Switzerland) and B2 – Reciproc file system (VDW, Munich, Germany) each containing 10 samples. All the teeth were mounted in the rubber base impression material. To maintain standardization, each file system with 0.25 tip was used in this study.
Samples underwent a preinstrumentation CBCT imaging (CS9300, Carestream Health Inc., Rochester, New York, USA) with the following parameters: 84 kVp, 5 mA, exposure time 20 s, and CBCT scan at 90 μm high dental resolution mode. After the preinstrumentation scan, groups were instrumented according to their manufacturer's instructions. During preparation, each instrument was coated with RC Prep (Premier products, PA) as a lubricant and the root canals were irrigated with 2 mL of 3% NaOCl between instruments. After preparation, the root canals were irrigated with distilled water and 2 mL of 3% NaOCl to remove all dentin debris. Each file was discarded after use in one canal or when any defect or deformation was observed in the file. Then, the samples were subjected to the CBCT imaging, and postinstrumentation images were taken in the same manner.
As the PCD extends 4 mm above and 4 mm below the CEJ, sections of 1 mm from this region were obtained, and the PCD thickness was analyzed for both the rotary and reciprocating single-file systems, i.e., Neolix [Figure 1]a and [Figure 1]b, Oneshape [Figure 1]c and [Figure 1]d, Reciproc [Figure 2]a and [Figure 2]b, and WaveOne [Figure 2]c and [Figure 2]d. The PCD thickness was calculated as the shortest distance from the canal outline to the closest adjacent root surface, which was measured in four surfaces, i.e., facial, lingual, mesial, and distal for all the groups in the two obtained scans.
|Figure 1: Cone-beam computed tomography images of rotary single-file systems. (a) Preoperative cone-beam computed tomography image of Neolix. (b) Postoperative cone-beam computed tomography image of Neolix. (c) Preoperative cone-beam computed tomography image of Oneshape. (d) Postoperative cone-beam computed tomography image of Oneshape|
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|Figure 2: Cone-beam computed tomography images of reciprocating single-file systems. (a) Preoperative cone-beam computed tomography image of Reciproc. (b) Postoperative cone-beam computed tomography image of Reciproc. (c) Preoperative cone-beam computed tomography image of WaveOne. (d) Postoperative cone-beam computed tomography image of WaveOne|
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Descriptive and inferential statistical analysis was carried out in the present study. Results on continuous measurements were presented on the mean ± standard deviation level of significance which was fixed at P = 0.05 and any value ≤0.05 was considered to be statistically significant.
Student's t-tests (two-tailed, paired) were used to find the significance of study parameters on continuous scale between two groups. Analysis of variance (ANOVA) was used to find the significance of study parameters between three or more groups followed by post hoc analysis if the ANOVA values were statistically significant.
The statistical software IBM SPSS statistics 20.0 (IBM Corporation, Armonk, NY, USA) was used for the analyses of the data, and Microsoft Word and Excel were used to generate graphs and tables.
| Results|| |
It was found that Reciproc system removed more PCD as compared to Oneshape, WaveOne, and Neolix at all surfaces (buccal, lingual, mesial, and distal) in all examined sections and Oneshape system removed more PCD as compared to WaveOne and Neolix at buccal, mesial, and distal surfaces in all examined sections [Graph 1].
| Discussion|| |
Root canal treated teeth are considered to be more prone to fracture than the vital teeth. The greatest incidence of vertical root fractures occurs in teeth that have undergone endodontic therapy. The strength of an endodontically treated tooth is related directly to the method of canal preparation and to the amount of remaining tooth structure. On studying the forces responsible for fracture of teeth, the focus has shifted from coronal to the cervical area of the tooth. The dentin in this critical area of tooth called as PCD is the dentin near the alveolar crest. While the apex of the root can be amputated, and the coronal third of the clinical crown removed and replaced prosthetically, the dentin near the alveolar crest is irreplaceable., This critical zone, roughly 4 mm above the crestal bone and extending 4 mm apical to crestal bone, is quite important for the strength of the tooth., There are 3 reasons for this: (1) ferrule, (2) tendency to undergo fracture, and (3) dentin tubule orifice proximity from inside to out.
The principles of rotary motion have been in clinical usage for close to 25 years now. However, the physics behind reciprocating motion is based on the “law of action and reaction,” which results in a balanced force during canal instrumentation, as theorized by Prabhakar et al. The first study experimenting with an alternating movement was that of Yared in 2008, which used the ProTaper F2 instrument (Dentsply/Maillefer) in a reciprocating movement. The reciprocating movement minimizes torsional and flexural stresses, increases the canal centering ability, and reduces the taper lock of the instrument within the canal. Recent studies have shown that an alternating reciprocating movement is a valid option to optimize endodontic instrumentation by reducing the risk of instrument fracture and root canal deformity. The use of such a reciprocating motion in place of continuous rotation could thus prove to be advantageous in terms of reducing the stress as well as the time required for the preparation of curved root canals.
Recently, Waveone and Reciproc NiTi single-file reciprocating systems have been introduced for better and simple root canal preparation. Only one single-shaping file is required to instrument the canal to an adequate size and taper. The main characteristics of this system are single use, a reciprocating action, and M-wire alloy manufacturing technology which improves strength and resistance to cyclic fatigue. Even more recently, one shape and Neolix files have been introduced in which complete canal shaping is possible with only one single file, which is used in continuous rotation. The major advantages of these system are their economic viability, unique design, and presterilized usage with zero cross-contamination.
Although a number of methods have been used to evaluate canal shape before and after instrumentation, CBCT imaging was employed for this study as it provides detailed three-dimensional observation as evidenced by the previous studies.,,,, The fact that CBCT provides images in orthogonal planes as well as in oblique planes is an added advantage for measuring dentin thickness, canal curvature, apical transportation, and canal centering.,
This experimental study investigated the removal of PCD induced by rotary single-file systems, Oneshape and Neolix, and reciprocating single-file systems, WaveOne, and Reciproc, on extracted teeth using CBCT. It was found that Reciproc system removed more PCD, followed by Oneshape and WaveOne, whereas Neolix system removed least PCD among all group of this study.
The findings of this experimental study are consistent with those of Manuel marques Ferreira et al., which concluded that the WaveOne systems account less wear index when compared to the Reciproc system an in vitro model. On the contrary, according to the investigation by Dhingra et al., who concluded that cervical dentinal removal is maximum at all levels for Oneshape and minimum for WaveOne showed the better quality of preparation by WaveOne over Reciproc and Oneshape file systems.
More PCD removal with Reciproc may be due to its stiffness and the cross-sectional design of the instrument. Reciproc has a sharp double-cutting edge and S-shaped geometry, while Neolix files have nonhomothetic rectangular cross sections with rounded Gothic tips. Furthermore, Neolix system does not have the usual metallic memory and tendency to rapidly return to straight position. The manufacturer claims that this special feature is due to the use of a newly developed wire-cut electrical discharge machining process and an appropriate heat treatment which causes the special progressive flexibility of the files.
| Conclusion|| |
Within the limitations of this study, we can conclude that the Reciproc and OneShape systems account for more PCD loss when compared to the WaveOne and Neolix systems in an in vitro model.
According to the present study, it can be revealed that the effect of the single-file system on PCD was not related to their motion, i.e., rotary/reciprocating, whereas it was dependent on the cutting efficacy of single-file system.
Further ex vivo and clinical studies should be performed to ascertain such differences.
Financial support and sponsorship
Conflicts of interest
There are no conflicts of interest.
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Priyanka Ramdas Zinge
Department of Conservative Dentistry and Endodontics, PMNM Dental College and Hospital, Bagalkot, Karnataka
Source of Support: None, Conflict of Interest: None
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