 Abstract | | |
Background: Optimal biomechanical preparation, thorough irrigation, proper disinfection, and finally, well-sealed obturation is a must to attain definitive success in root canal procedure. Proper preparation of the root canal is all the more imperative to establish a hermetic apical seal with adequately placed filling materials. The present study was conducted for comparing the Cleaning Efficiency of F360 system and the WaveOne Gold (WOG) system of rotary NiTi instrumentation for a root canal.
Materials and Methods: One hundred freshly extracted noncarious mandibular canines were obtained. Access cavity of standard size was made followed by the establishment of working length. Afterward, random division of all the specimens was done into two study groups: group A: the group in which F360 system was used for instrumentation and group B: the group in which the WOG system was used for instrumentation. Irrigations of all the specimens of both the study groups were done followed by root canal shaping by the instrument system of their respective study groups. Scanning electron microscope (SEM) was used for assessment after specimens were cut buccolingually. Debris score and residual smear layer score were used for assessment.
Results: Among group A specimens, the mean smear layer score at the coronal third, middle third, and apical third was 1.76, 2.39, and 2.65, respectively. Among group B specimens, the mean smear layer score at the coronal third, middle third, and apical third was 1.34, 1.59, and 1.92, respectively. While analyzing statistically, it was seen that the mean smear layer score was significantly higher among specimens of group A in comparison to group B. While analyzing statistically, it was seen that the mean debris score was significantly higher among specimens of group A in comparison to group B.
Conclusion: The cleaning effectiveness of WOG instruments was significantly enhanced in comparison to F360 equipment.
Keywords: NiTi instrumentation; root canal; rotary
How to cite this article:
Vashisht R, Kumar U, Jhamb S, Singla R. Comparative evaluation of cleaning efficiency of single file NiTi rotary system during root canal treatment procedure - A scanning electron microscope study. J Conserv Dent 2023;26:316-20 |
How to cite this URL:
Vashisht R, Kumar U, Jhamb S, Singla R. Comparative evaluation of cleaning efficiency of single file NiTi rotary system during root canal treatment procedure - A scanning electron microscope study. J Conserv Dent [serial online] 2023 [cited 2023 Jun 5];26:316-20. Available from: https://www.jcd.org.in/text.asp?2023/26/3/316/376912 |
| Introduction | |  |
Root canal instrumentation results in the formation of a smear layer. It is composed of both organic as well as inorganic components such as the odontoblastic process, debris of the pulp tissue, microbes, and even some blood cells.[1] A large amount of mineralized debris is produced owing to the cutting of the dentin by both rotary as well as hand instruments. This debris which ultimately forms the smear layer on the dentinal surface is basically a mineralized matrix of collagen.[2],[3] Optimal biomechanical preparation, thorough irrigation, proper disinfection, and finally, well-sealed obturation is a must to attain definitive success in root canal procedure.[4] Proper preparation of the root canal is all the more imperative to establish a hermetic apical seal with adequately placed filling materials. The existence of a smear layer proves to be hazardous by preventing the intracanal irrigants as well as the medicaments to penetrate into the dentinal tubules.[5]
Nevertheless, whether the success of root canal therapy depends on the proper removal of the smear layer has not been verified beyond doubt. Even then there seems to be a more logical debate favoring its removal rather than retaining it. A proper usage of certain organic solvents, acidic solutions, and even some chelating agents is required in combination for effective removal of the smear layer.[6] The F360 (Komet, Brasseler GmbH and Co., Lemgo, Germany) is a higher-generation and recently introduced single-use system utilizing multi-file Ni-Ti techniques. A modified S-shaped cross-sectional design is used for the entire working part of the file.[6],[7] WaveOne Gold (WOG) (DentsplyMaillefer, Ballaigues, Switzerland) is a single-file reciprocating system with a rectangular cross-section. These files provide better flexibility and resistance to fracture as they are made of NiTi Gold alloy.[7] Hence; the present study was conducted for comparing the cleaning efficiency of F360 system and the WOG system of rotary NiTi Instrumentation for a root canal.
| Materials and Methods | | |
One hundred freshly extracted noncarious mandibular canines were obtained. These specimens were obtained from patients who underwent extraction due to periodontal reasons. Carious, grossly decayed, and malformed tooth specimens were excluded. All the specimens were cleaned under running tap water for removing soft-tissue debris. Calculus, if any, was removed by a scaler. Access cavity of standard size was made using round end bur followed by the establishment of working length using #10 stainless steel K-file. By subtraction of 0.5 mm from the actual length, working length was assessed. Random division of all the specimens was done into two study groups:
- Group A: Group in which F360 system was used for instrumentation
- Group B: Group in which WOG system was used for instrumentation.
Both these systems were employed since both these systems are a single file system. Irrigations of all the specimens of both the study groups were done using a mixture of 5.25% Sodium hypochlorite (NaOCl), and 17% Ethylenediaminetetraacetic acid (EDTA). After finishing the initial phase of irrigation, one ml of forty percent citric acid was used for the final flush. After competition of root canal cleaning procedure, sectioning of all the specimens was done buccolingually. Scanning electron microscope (SEM) was used for the assessment of the cut surface. Debris score criteria and residual smear layer criteria were used for the evaluation of the effectiveness of both systems. Debris score criteria were as follows:
- Score 1 ‒ Root canal walls that are free of even the tiniest pieces of detritus
- Score 2 ‒ Few large clusters of trash
- Score 3 ‒ Approximately 50% of the root canal wall is covered by a thick layer of debris
- Score 4 ‒ In more than half of the root canals, there was a layer of debris and
- Score 5 ‒ Debris covers the whole or almost the entire root canal wall.[7]
Residual smear layer score was as follows:
- Score 1 ‒ Dentinal tubules were completely free of any smear layer
- Score 2 ‒ One or two dentinal tubules were exposed, as well as some smear layer
- Score 3 ‒ Few dentinal tubules are exposed due to a uniform smear on the root canal's wall
- Score 4 ‒ A uniform smear layer covered the whole root canal wall, and no exposed dentinal tubules could be seen and
- Score 5 ‒ Root canal walls are covered with a thick, homogenous smear layer.[7]
Statistical analysis was performed using Mann–Whitney U test. P < 0.05 was considered statistically significant.
| Results | | |
On SEM analysis, the presence of smear layer on the canal wall and the orientation of dentinal tubules is demonstrated in [Figure 1]a. Patient dentinal tubules and the presence of smear layer are shown in [Figure 1]b and [Figure 1]c, respectively. SEM analysis showing penetration of dentinal tubules by smear layer is highlighted in [Figure 1]d. Among group A specimens, the mean smear layer score at the coronal third, middle third, and apical third was 1.76, 2.39, and 2.65, respectively. Among group B specimens, the mean smear layer score at the coronal third, middle third, and apical third was 1.34, 1.59, and 1.92, respectively [Table 1]. While analyzing statistically, it was seen that the mean smear layer score was significantly higher among specimens of group A in comparison to group B. Among group A specimens, the mean debris score at the coronal third, middle third, and apical third was 1.59, 1.86, and 2.12, respectively. Among group B specimens, the mean debris score at the coronal third, middle third, and apical third was 1.69, 1.91, and 2.01, respectively [Table 2]. While analyzing statistically, it was seen that the mean debris score was significantly higher among specimens of group A in comparison to group B. | Figure 1: (a) Presence of smear layer on the canal wall and orientation of dentinal tubes, (b) Patent dentinal tubules, (c) Presence of smear layer, (d) Smear layer penetrating dentinal tubules
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 | Table 1: Mean smear layer removal score at different levels of the root canal among specimens of group A
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 | Table 2: Mean debris score at different levels of the root canal among specimens of group A
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| Discussion | | |
The root canal system must be shaped and cleaned during endodontic treatment to remove necrotic pulp tissue, diseased dentin, and debris so that the periapical healing process can begin. Some of these objectives were tested in vitro in this work using rotating NiTi devices such as the F360 and WOG. We do not have a lot of data on how well these two tools work yet on natural teeth. Two separate parameters were used in this study to evaluate the cleaning efficiency of the instrument: (a) debris and (b) smear layer. In the majority of instances, dentinal chips and the pulpal tissue were adhered to the walls of the root canal. As a result, there was a possibly an inadequate elimination of the microbes from the root canals.[12],[13],[14]
Smear layer can be described as a thin inorganic layer, produced due to instrumentation within the root canals. It is pertinent to remove this layer to allow the irrigants and the medicaments to properly clean the dentinal tubules, failing which the entire treatment may be jeopardized.[6] This smear layer can potentially be eliminated with the concomitant usage of antimicrobial irrigants and chelating agents.[7],[8],[9]
This experiment made use of sodium hypochlorite, citric acid, and EDTA. Recent studies have highlighted the role of chelating agents (containing EDTA) as well as citric acid in the effective cleanup of trench divider after instrumentation with NiTi instruments, thereby improving potentially the cleaning properties of the two equipment which are used in this study.[10],[11],[15]
In the present study, WOG group of equipment were found to be more efficient than F360 group for the removal of smear layer and debris. This is in accordance with a study conducted by Dagna et al. Their study found the effectiveness of F6 Skytaper was greater than F360. A constant as well as a lesser degree of taper of F360 (0.4%) could be the reason for its lesser efficiency when compared with WOG with a 0.7% taper. Greater taper potentially allows for greater flow of irrigants and medicaments to clean the root canals. Similar results were seen in a study carried out by Usman et al., in which an increase in the size of the instrumented area showed increased canal cleanliness.[13] On SEM analysis, the presence of smear layer on the canal wall and the orientation of dentinal tubules is demonstrated in [Figure 1]a. Patient dentinal tubules and the presence of smear layer are shown in [Figure 1]b and [Figure 1]c, respectively. SEM analysis showing penetration of dentinal tubules by smear layer is highlighted in [Figure 1]d. Our results were also in concordance with the results obtained by Agrawal et al. who showed that F360 instrument demonstrated a statistically significant difference for smear layer removal among all thirds of the root canal, whereas WOG resulted in a significant difference when the apical third was compared to the middle and coronal third.[7] The results of this study were evaluated by a SEM It offered not only high definition but also three-dimensional images with greater resolution and magnification. A plethora of techniques has been evaluated to check the cleanliness within the root canals such as the histological sections and even different types of microscopes.
The study conducted by Suparna et al. and Seck et al. also claimed that WOG files produce cleaner canals after instrumentation when compared with other systems. This may be attributed to the taper characteristics of this file system. Its parallelogram cross-section also adds to its greater efficiency while cleaning the root canals. These design characteristics lead to minimal contact between the instrument and the dentin, thereby minimizing the potential lateral compaction of the layer of debris within the dentinal tubules generated during instrumentation.[14],[15],[16] The inference derived from this study was similar to the study carried out by Bartols et al. The latter observed that the cleaning efficiency of a single file system of WOG was highest and F360 was next in order.[17] The inferences of this study were similar to another study carried out by de Carvalho et al. The latter study emphasized that the implementation of reciprocating action while instrumentation prevented the generation of an increased quantity of debris in comparison to a continuous rotary action.[18],[19],[20] Al-Khafaji and Al-Huwaizi and Koçak et al. showed that WOG was most efficient in the removal of smear layer when compared with other instruments. Greater effectiveness of WOG over F360 was attributed to its reciprocating motion as opposed to the continuous motion of F360.[21],[22] In another previous study conducted by Dagna et al., authors assessed the effectiveness of F360 and F6 Skytaper in removing smear layer. Their research did not reveal any significant differences in between both the study groups at the coronal and apical third. Highest value of score was observed at the apical third portion for all Ni-Ti systems used. Significant variation in the score of the residual smear layer was seen in their study at the middle canal level (P < 0.05), where F6 Skytaper showed significantly lower scores than F360.[23] Yoo and Cho conducted a study in which they comparatively evaluated Reciproc®, Wave One®, ProTaper®, Profile®, and K-files, by placing over the pretreatment and posttreatment pictures with microscope. They did not appreciate any significant variation in the preservation of the anatomy of the pulp canal on comparing.[24] In a similar research carried out by Rubio et al., authors comparatively evaluated the cutting efficacy of F360®, F6-SkyTaper®, Hyflex-EDM®, iRACE®, Neoniti®, O. Shape®, P. Next®, Reciproc®, Revo-S®, and WaveOne Gold® size 25 files. They included three hundred tooth specimens and divided them into ten different study groups according to the type of system employed. Using disc bur, three cross-sections of all the specimens were obtained and were analyzed under stereo-microscope. An assessment of pre-instrumentation data was done. This was followed by re-forming of tooth specimens. The creation of glide path was done. They concluded that P. Next® and Reciproc® were superior in the coronal third.[25] De-Deus G, in a similar study, comparatively evaluated the % of noninstrumented area in pulp canal which was prepared using various single-file reciprocating systems. The systems of rotary they employed in their study were Reciproc and WaveOne. Furthermore, a conventional system was also used in their study which was BioRaCe system. The final assessment and comparison of all the systems were done by micro-computed tomographic evaluation. They evaluated 30 mesial roots of mandibular molars. Only those specimens employed by them which had moderate curvature (10° to 20°). Other inclusion criteria for assessing mandibular molars were type II Vertucci canal configuration. They concluded that neither system could prepare the entire surface area of the mesial root canal of mandibular molars.[26]
In the last couple of decades, dentists have tried various rotary and reciprocating systems. In the current scenario, NiTi systems have been a part of recent research.[27],[28],[29],[30],[31] The standards of root canal preparation techniques have been raised by the introduction of reciprocating systems. The learning curve of these systems is moving the interest in their direction because of its simplification nature of technique.[32],[33],[34],[35] Tietz et al., in another past research assessed and compared the effectiveness of three different reciprocating systems. They evaluated 40 mesiobuccal roots of maxillary molars. Preparation of all the root canal was done followed by obturation. The assessment was done by micro-computed tomography analysis. Random division of all the specimens was done into four study groups as follows: Manual, Reciproc Blue, WOG, and X1 Blue. They observed that in relation to removing the filling material, maximum efficacy was demonstrated by WOG. However, none of the systems resulted in the removal of all filling material.
| Conclusion | | |
The cleaning effectiveness of WOG instruments was significantly enhanced in comparison to F360 equipment. Higher debris and smear formation occur in the apical one-third of the root. Hence further researchers in the future are recommended.
Clinical significance
WOG instrument system could be used effectively in the field of endodontics for improving the prognosis and quality of root canal therapy.
Financial support and sponsorship
Nil.
Conflicts of interest
There are no conflicts of interest.
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Correspondence Address:
Dr. Ruchi Vashisht
House Number 1101, Sector 21B, Chandigarh - 160 022
India
 Source of Support: None, Conflict of Interest: None  | Check |
DOI: 10.4103/jcd.jcd_52_23
[Figure 1]
[Table 1], [Table 2] |
