|Year : 2016 | Volume
| Issue : 1 | Page : 17-21
A SEM evaluation of smear layer removal using two rotary instrument systems with EDTA and vinegar as a root canal irrigant
Udayakumar Palaniswamy1, Mamta Kaushik2, Lakkam Ram Surender1, Neha Prashar2, Shikha Arya1, Srikanth Pasari1
1 Department of Conservative Dentistry, SVS Institute of Dental Sciences, Mahabubnagar, Telangana, India
2 Department of Conservative Dentistry, Army College of Dental Sciences, Secunderabad, Telangana, India
|Date of Web Publication||9-Feb-2016|
Dr. Udayakumar Palaniswamy
SVS Institute of Dental Sciences, Appanapally, Mahabubnagar, Telangana
Source of Support: None, Conflict of Interest: None
Introduction: As the smear layer (SL) produced during instrumentation adheres to the dentinal surface and prevents penetration of irrigants and medicaments, it should be removed. The aim of this study was to evaluate the ability of 17% ethylenediaminetetraacetic acid (EDTA) and white vinegar (5% pure acetic acid) to remove debris and SL produced during root canal preparation with two nickel-titanium (NiTi) file systems, Hyflex (Coltene Whaledent, Allstetten, Switzerland) and ProTaper (Dentsply, Tulsa, OK, USA). Materials and Methods: Twenty freshly extracted human, single-rooted teeth were sectioned at the cementoenamel junction and were randomly divided into four groups of five samples each. In each group, 0.5 mL of 5% NaOCl was used as the first irrigant, which was followed by either 17% EDTA or vinegar. Two groups were prepared with Hyflex rotary files and the other two with ProTaper files. Scanning electron microscopy (SEM) study was done to evaluate the SL, and the collected data were submitted for statistical analysis. Statistical analysis was performed based on Student's t-test with P value >0.05. Results: There was no statistically significant difference between the types of instruments used (Hyflex files and ProTaper files), and 17% EDTA solution and vinegar (5% acetic acid). Conclusion: Vinegar can be relied on as an endodontic irrigant for SL removal was comparable to 17% EDTA. In addition, both types of NiTi instrument produced similar dentin surface in terms of SL when used along with EDTA and vinegar.
Keywords: Distilled vinegar, ethylenediaminetetraacetic acid, Hyflex files, ProTaper files, scanning electron microscopy, smear layer
|How to cite this article:|
Palaniswamy U, Kaushik M, Surender LR, Prashar N, Arya S, Pasari S. A SEM evaluation of smear layer removal using two rotary instrument systems with EDTA and vinegar as a root canal irrigant. J Res Dent 2016;4:17-21
|How to cite this URL:|
Palaniswamy U, Kaushik M, Surender LR, Prashar N, Arya S, Pasari S. A SEM evaluation of smear layer removal using two rotary instrument systems with EDTA and vinegar as a root canal irrigant. J Res Dent [serial online] 2016 [cited 2019 May 25];4:17-21. Available from: http://www.jresdent.org/text.asp?2016/4/1/17/176020
| Introduction|| |
Dentin debris and smear layer (SL) are created on the root canal walls as a consequence of endodontic instrumentation. , According to the American Association of Endodontists, SL is defined as a surface film of debris retained on dentin or other surfaces after instrumentation with either rotary or endodontic files, consisting of remnants of vital or necrotic pulp tissue, dentin particles, retained irrigant, and bacterial components. 
If the debris in the SL gets packed into the dentinal tubules of the prepared canal walls, it provides nutrients to bacteria, prevents the access of irrigants and medicaments into the infected dentinal tubules, and also reduces the adaptation of sealer and gutta percha. , Furthermore, if this debris is condensed apically, an apical plug is created that results in incomplete filling of the root canal. 
It has been shown that the maximum effect for the dissolution of SL can be obtained by using ethylenediaminetetraacetic acid (EDTA) followed by NaOCl solutions at different concentrations and volumes. ,, However, Baumgartner and Mader  observed irregular erosion on root canal walls and at the orifices of dentin tubules on sequential use of EDTA and NaOCl. Calt and Serper  stated that this erosive effect is mainly due to the EDTA.
Acid solutions that have been recommended for removing the SL include sodium salt of EDTA, citric acid, orthophosphoric acid, malic acid, and tetracycline HCl.  Several studies ,, have been done to evaluate the efficacy of apple vinegar for SL removal when compared to white vinegar. The main composition of distilled white vinegar is acetic acid, whereas for apple vinegar it is malic acid.
A relatively rapid approach for canal preparation is through nickel-titanium (NiTi) instruments. The thickness, type, and amount of SL produced by these instruments must be assessed.  ProTaper and Hyflex NiTi files have different designs: Their cross-sections, helical angles, and radial lands result in variations in their debris removal and SL production. Hyflex NiTi rotary file is compared with ProTaper in this study. ProTaper features a varying taper along the length of the instrument and the cross section being triangular with convex sides. Hyflex NiTi rotary file has been produced by a new methodology where a unique process controls the material's memory. The cross section of this system is double-fluted, same as the Hedstrom file, with uniform taper. Some instruments have triangular cross section with three blades and three flutes, while others have quadrangular cross section with four blades and four flutes.
This study was done to evaluate, by scanning electron microscopy (SEM), the ability of 17% EDTA and 5% distilled vinegar to remove debris and SL produced during root canal preparation using two NiTi file systems.
| Materials and Methods|| |
This study was approved by the Ethics Committee of the Army College of Dental Sciences. Twenty human, single-rooted teeth with straight canals, sectioned at the cementoenamel junction, were selected for this study. The working length was determined and half of the samples were prepared with Hyflex rotary files (Coltene Whaledent, Allstetten, Swizerland) till. 04/30 and half of the samples were prepared with F3 (6%) ProTaper rotary files (Dentsply, Tulsa, OK, USA). In case of ProTaper, the cervical region of root canal was prepared using S1 and SX files, which was followed by the use of S1, S2, F1, F2, and F3 files up to the working length. For Hyflex, .08/25 was used as orifice opener followed by .04/20, .04/25, .06/25 and .04/30. The teeth were randomly divided into four groups of five samples each.
In each group, 0.5 mL of 5% NaOCl (Vishal Diagnostics, Lucknow, UP, India) was used with first instrumentation.
Group 1: This group was prepared with Hyflex rotary files; 0.5 mL of 5% NaOCl and 0.5 mL of 17% EDTA (Canallarge, Ammdent, Mohali, PB, India) were used alternatively. A new file was employed for each tooth. A final 1 mL solution of 17% EDTA was used for 1 min.
Group 2: This group was prepared with Hyflex rotary files; 0.5 mL of 5% NaOCl and 0.5 mL of vinegar (5% acetic acid, American Garden, New York, NY, USA.) were used alternatively. A final 1 mL solution of vinegar was used for 1 min.
Group 3: This group was prepared with ProTaper files; 0.5 mL of 5% NaOCl and 0.5 mL of 17% EDTA were used alternatively. A final 1 mL solution of 17% EDTA was used for 1 min.
Group 4: This group was prepared with ProTaper files; 0.5 mL of 5% NaOCl and 0.5 mL of vinegar were used alternatively. A final 1 mL solution of vinegar was used for 1 min.
The files were changed for each tooth. Finally, the root canals were irrigated with 5 mL of distilled water, dried with paper points, stored in dry sterilized containers, and submitted for SEM study.
Sample preparation for scanning electron microscopy
Longitudinal grooves were made using a slow-speed carborundum disk on the root surface. Then the root was split with a chisel into two corresponding halves. The most suitable hemisection of each tooth was selected for SEM examination. The specimens were analyzed at 1000× magnification at the middle third of the root.
SEM scans were evaluated by an examiner who was unaware of the irrigation regimen and preparation mode employed for each group. Scoring criteria were according to the rating system developed by Rome et al., as follows. 
0: No SL, dentinal tubule open and free from debris.
1: Moderate SL, outlines of dentinal tubules visible or partially filled with debris.
2: Abundant SL, preventing the visualization of dentinal tubule openings.
The attributed scores were tabulated and submitted for statistical analysis.
| Results|| |
On analysis, 17% EDTA seems to have an edge over 5% vinegar. Results obtained with 5% vinegar showed some variability, between no SL to moderate SR. Both the NiTi instruments produced a similar dentin surface on root canal walls, with slightly higher efficacy of the ProTaper instrument [Figure 1].
|Figure 1: (A) SEM showing samples prepared with ProTaper with 17% EDTA (B) SEM showing samples prepared with Hyflex with 17% EDTA (C) SEM showing samples prepared with ProTaper with vinegar (D) SEM showing samples prepared with Hyflex with vinegar|
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Statistical analysis based on the t-test for distribution of mean value in removal of SL by two irrigants irrespective of instruments showed no significant difference (P = 0.1964) between EDTA and vinegar, though EDTA had a lower score [Table 1]. When removal of SL by two rotary instruments was compared irrespective of the irrigant, there was no statistically significant difference between Hyflex and ProTaper rotary (P = 0.6733) [Table 2].
|Table 1: Distribution of mean value in removal of SL by two irrigants irrespective of instruments P = 0.1964 (ns) |
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|Table 2: Distribution of mean value in removal of SL by two types of instruments irrespective of irrigant P = 0.6733 (ns) |
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When distribution of mean value in removal of SL by the irrigant with Hyflex file was analyzed statistically there was no significant difference between the two irrigants (P = 0.57) [Table 3]. Similarly, no statistically significant difference was observed between EDTA and vinegar when prepared with ProTaper rotary file (P = 0.2429) [Table 4].
|Table 3: Distribution of mean value in removal of SL by the irrigant with Hyflex file P = 0.5796 (ns) |
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|Table 4: Distribution of mean value in removal of SL by the irrigant with ProTaper file P = (ns) |
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| Discussion|| |
In the endodontic literature, a variety of chemicals with different irrigation regimens have been described to remove the SL. In this study, distilled vinegar was used as an experimental solution to possibly remove SL, and in comparison with a well-known chelating agent, i.e., EDTA, which is widely used to remove SL in the root canal.
White vinegar contains 5% pure acetic acid. This is an edible vinegar with a pH of 2.4. It is produced by the fermentation of ethanol into acetic acid, which is performed by bacteria.
Acetic acid is one of the weakest acids, and is biocompatible. Among vinegars, 5% distilled vinegar has shown the strongest bactericidal activity. Vinegar is easily available at a reasonable cost.
Other medical uses of vinegar include soothing of sunburn and psoriasis, and use in diet to lower cholesterol, control blood pressure, control blood glucose, for diabetic management, etc. Miscellaneous uses of vinegar include as a preservative for pickling, food additive (e.g., in Chinese cuisine), hair conditioner, natural deodorant, household cleansing agent, and herbicide. ,,
EDTA reacts with the calcium ions present in the dentin, resulting in the formation of soluble calcium chelates. The chelating energy of EDTA is more pronounced than its demineralizing activity.  Calt and Serper  reported that 17% EDTA completely removed the SL by causing aggressive erosion of the tubuli over time, and concluded that a lower percentage of EDTA should be used. EDTA when used for more than 1 min causes erosion of dentinal tubules. Hence, in this study we used both the irrigants as a final rinse for 1 min. 
On comparing EDTA and vinegar individually [Table 1], some amount of variability was shown by 5% vinegar with no SL to moderate SL in some areas of dentin, whereas in most of the samples treated with EDTA, a substantial portion of dentin was free from SL. Although EDTA had a comparatively lower score than vinegar, the difference was not statistically significant. This could be attributed to the study's smaller sample size. EDTA has an edge over vinegar, which could be because of the chelating property of EDTA.
Morphological differences in the designs of rotary NiTi instruments result in variations in their debris removal and SL production. In this study, Hyflex has been compared with ProTaper. Both the instruments were used as per manufacturer's instructions, and the irrigation regimen was standardized.
Despite the differences observed, in the cross section it was observed that both NiTi instruments produced a similar dentin surface on root canal walls, with ProTaper showing slightly higher efficacy [Table 2]. The higher efficacy of ProTaper may be attributed to the flute design combining multiple tapers within the shaft, aimed at reducing the contact area between the instrument and the canal wall. The debris space increases from tip to shaft in order to facilitate the removal of dentin and debris.
On taking into consideration both the irrigants and the files [Table 3] and [Table 4], the ProTaper and EDTA group showed slightly better SL removal when compared to the Hyflex group, but the results were not statistically significant.
Within the limitations of our study, EDTA was proved to be more efficient than 5% vinegar. The action of distilled vinegar (5% acetic acid) may be enhanced by further increasing the time and volume of the irrigant used, and that needs to be further evaluated. At the same time, its effect on the microhardness of dentin as well as the maximum time it can be in contact with dentin without causing erosion should also be evaluated.
In the present study, SEM evaluation was done only for middle third of the root; further studies on the apical third with larger sample sizes should be done as a greater amount of debris gets accumulated in this area.
| Conclusion|| |
EDTA is more efficient in SL removal, while vinegar can be relied on as an endodontic irrigant because of its easy availability at a reasonable cost, its antibacterial property, and nearly similar results to EDTA in SL removal.
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[Table 1], [Table 2], [Table 3], [Table 4]