| Abstract|| |
Aims & Objectives: The purpose of this study was to investigate the effects of 5.25% sodium hypochlorite (NaOCl) and 2% chlorhexidine (CHX) on Gutta-percha and Resilon cones using an atomic force microscope (AFM).
Materials and Methods: Gutta-percha cones (n = 15) and Resilon cones (n = 15) were cut 3 mm from their tip, attached to a glass slide with cyanoacrylate glue and immersed in 5.25% NaOCl and CHX for 1, 5, 10, 20 and 30 min. Five each of Gutta-percha and Resilon cones not treated with any disinfectant were used as control. The analysis of the surface topography was performed on the region between 1 and 2 mm from the tip using the AFM. The root mean square (RMS) parameters for contact mode imaging were measured. The differences between RMS values were tested by SPSS-16.0 version statistical software [IBM SPSS (Statistical Product and Service Solutions) Data Software, Chicago, US] using Kruskal-Wallis ANOVA, Mann-Whitney U-test and Wilcoxon matched pairs test.
Results: There was no deterioration in the surfac e topography of Gutta-percha and Resilon when treated with 2% CHX in comparison to baseline (P < 0.05). Resilon exhibited no deterioration in topography when immersed in 5.25% NaOCl. There was a significant decrease in the mean RMS values of Gutta-percha treated with NaOCl from the control at time intervals of 1, 5, 10, 20 and 30 min.
Keywords: Chlorhexidine; Gutta-percha; Resilon; sodium hypochlorite and atomic force microscope
|How to cite this article:|
Tilakchand M, Naik B, Shetty AS. A comparative evaluation of the effect of 5.25% sodium hypochlorite and 2% chlorhexidine on the surface texture of Gutta-percha and resilon cones using atomic force microscope. J Conserv Dent 2014;17:18-21
|How to cite this URL:|
Tilakchand M, Naik B, Shetty AS. A comparative evaluation of the effect of 5.25% sodium hypochlorite and 2% chlorhexidine on the surface texture of Gutta-percha and resilon cones using atomic force microscope. J Conserv Dent [serial online] 2014 [cited 2021 Sep 17];17:18-21. Available from: https://www.jcd.org.in/text.asp?2014/17/1/18/124102
| Introduction|| |
Obturation is an important procedure in endodontic treatment. Gutta-percha, is at present, the most commonly used material for the obturation of the root canal system. It is biocompatible, dimensionally stable, radiopaque and thermoplastic. Recently, a new thermoplastic, filled polymer that has the potential to challenge Gutta-percha as a root filling material has been introduced. The thermoplasticity of Resilon is provided by polycaprolactone which is a biodegradable polyester with a moderately low melting point. Its bond ability is derived from the inclusion of resin with methacryloxy groups. 
According to concepts of infection control, every instrument and material placed within the root canal should be sterile. Core filling materials, such as Gutta-percha and Resilon cones should be sterilized before placing them within the root canal. These materials are thermolabile and are provided sterile by the manufacturer. Even then, they should be chemically disinfected chair side before use in patients. 
A large variety of chemical disinfectants have been used to sterilize Gutta-percha cones before root canal filling. These include sodium hypochlorite (NaOCl), glutaraldehyde, alcohol, chlorhexidine (CHX), hydrogen peroxide, polyvinylpyrrolidone iodine and MTAD, Mixture of doxycycline, 10% citric acid and tween-80. A 5.25% NaOCl solution is recognized as an effective decontaminant. It was found to be effective against a variety of Gram-positive, Gram-negative and spore-forming microorganisms. ,,
Studies have shown, that as a strong oxidizing agent, 5.25% NaOCl causes extreme topographic alterations in the cones, which might be indicative of aggressive deterioration. Moreover, crystal formation on the surface of Gutta-percha cones has been identified after rapid sterilization with 2.5% and 5.25% NaOCl. Therefore an effective, but safer chemical is desirable for disinfecting Gutta-percha cones. It has been shown that a 30 min exposure to 2% CHX does not change the properties of Gutta-percha. This suggests that CHX may be less prejudicial to the structure of Gutta-percha. However, the effect of 2% CHX on the integrity of Gutta-percha points has not been fully investigated.
The advent of atomic force microscope (AFM), a member of the scanning probe microscopes family; has opened several applications in surface studies of different materials. The key principle of the AFM is the probing of a sample surface with a small tip attached to a flexible cantilever. The detection of the several parameters between the tip and the sample interactions provides qualitative and quantitative information about the sample. ,
The proposed study evaluates the effect of 2% CHX and 5.25% NaOCl on surface topography of Gutta-percha and resilon cones, using an AFM.
| Materials and Methods|| |
This study was conducted in the Department of Conservative Dentistry, SDM college of Dental sciences and Hospital, Dharwad. The purpose of this study was to evaluate the effect of 5.25% NaOCl and 2% CHX on surface texture of Gutta-percha and Resilon cones.
15 40 size Gutta-percha (Dentsply) and Resilon (Epiphany) cones each were cut 3 mm from their tip and attached to a glass slide measuring 5 mm × 5 mm using the rapid setting cyanoacrylate glue. These glass slides were prepared with the help of a diamond glass cutter. Following these procedures the samples were divided into four groups as following:
- Group I: Five Gutta-percha cones were immersed in 5.25% NaOCl (Rankem) for 1, 5, 10, 20 and 30 min respectively.
- Group II: Five Gutta-percha cones were immersed in 2% CHX (V-Consept) for 1, 5, 10, 20 and 30 min respectively.
- Group III: Five Resilon cones were immersed in 5.25% NaOCl for 1, 5, 10, 20 and 30 min respectively.
- Group IV: Five Resilon cones were immersed in 2% CHX for 1, 5, 10, 20 and 30 min respectively.
Five each of Gutta-percha and Resilon cones, which were not treated with any disinfectant, were used as control. After immersion, the samples were thoroughly rinsed with 5 ml of distilled water and the specimen was dried with filter paper. Each slide was viewed under an AFM using contact mode and the analysis was performed at a region located between 1 and 2 mm from the tip of the cones [Figure 1] and, [Figure 2]. AFM images of the Gutta-percha samples were recorded in the contact mode operation of the AFM (M/S Digital Instruments, USA). Typical AFM probes (length 115 μ and curvature radius 10 nm) mounted on silicon nitride cantilever with spring constant of 0.58 N/m were used. Resonance frequency nominal of 57 kHz was used. Scanned areas (5 Hz) were a perfect square.
AFM images were processed with the Scanning Probe Microscope (SPM) lab 4.0 Software [BME (BioMedical Engineering) 499/Biostat 642] and analyzed with WSxM SPM software 2.0. For the purpose of comparison, root mean square (RMS) roughness was chosen to investigate the topographic alteration of Gutta-percha and resilon cones.
Statistical analysis was performed using statistical software-SPSS-16.0 version using Kruskal-Wallis ANOVA, Mann-Whitney U-test and Wilcoxon matched pairs test.
| Results|| |
The following tables show the mean values of RMS for CMI profiles:
For group I RMS values were significantly lower when compared to the control with respect to 1 min, 5 min, 10 min, 20 min and 30 min of exposure to NaOCl [Table 1] and [Table 2]. Group II, III and IV showed no significant difference in the RMS values with different time exposures when compared with the control [Table 2] and [Table 3].
|Table 2: RMS values for CMI profiles of group I, II at different time intervals|
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|Table 3: RMS values for CMI profiles of group III, IV at different time intervals|
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There was a significant decrease in the mean RMS values of group I from the baseline (P < 0.05) at time intervals of 1 min, 5 min, 10 min, 20 min and 30 min [Table 4].
There was a significant difference in the RMS values between the groups.
There was a significant difference (P < 0.05) between group I and group II at time intervals of 5, 10, 20 and 30 min. There was no significant difference between group III and IV at all-time intervals [Table 5].
Comparison of time intervals in each group by Wilcoxon matched pairs test
Showed that there was a significant difference (P < 0.05) in the RMS values for group I at all the different time intervals when compared to the baseline. There was a significant difference in the RMS value for group II at time period of 1 min, 5 min and 20 min.
| Discussion|| |
The prevention of contamination of the root canal system is an important aspect of endodontic therapy. Materials such as Gutta-percha and resilon are manufactured under aseptic conditions, but they can be contaminated by handling, by aerosols and by physical sources during the storage process. The sterilization by conventional processes using moist or dry heat is not possible because of their thermoplastic characteristics. Therefore, a rapid chair-side chemical disinfection is needed. 
Gutta-percha cones exposed in clinics can be contaminated (19.4%) and the contaminating bacteria are all vegetative rather than resistant bacterial spores. Gutta-percha cones might also play a role in initiating biofilm infections in cases of over obturation showing periapical lesions. 
NaOCl solutions of 0.5-5.25% have a recognized tradition of use as an irrigating solution in endodontic practice.  5.25% NaOCl solution is recognized as an effective decontaminant.  It has antibacterial and sporocidal activity related to the liberation of active chlorine. 
A 5.25% NaOCl solution is routinely used as an effective chemical for rapid decontamination of Gutta-percha cones before use, killing microorganisms in 1 min of exposure time. Studies have shown, that as a strong oxidizing agent, 5.25% NaOCl causes extreme topographic alterations in the cones, which might be indicative of aggressive deterioration. Moreover, crystal formation on the surface of Gutta-percha cones has been identified after rapid sterilization with 2.5% and 5.25% NaOCl. Valois et al. reported that 5.25% NaOCl resulted in surface deterioration of Gutta-percha cone and that it was due to the loss of Gutta-percha cone components by the oxidizing agent (NaOCl). Therefore an effective, but safer chemical is desirable for disinfecting Gutta-percha cones. ,,
Currently, there is an increasing interest in the antibacterial activity of CHX in endodontic practice. It has antibacterial properties with broad spectrum and relatively low toxicity. Nevertheless, it has been reported that it is ineffective against spores except at high temperatures. CHX has additional properties such as substantivity and biocompatibility compared with NaOCl. CHX is less prejudicial to the structure of Gutta-percha. However, the effect of 2% CHX on the integrity of Gutta-percha points has not been fully investigated. ,,,,
The scanning electron microscope (SEM) has long been the standard means of investigation of surface characteristics of Gutta-percha cones. They needs to be operated under vacuum and uses an electron beam to give a 2-Dimensional "photographic" image of the sample covered with a layer of a conductive material such as gold; but cannot provide quantitative data regarding the topography. SEM and AFM resolve structures down to the nanometer scale. However, the image formation mechanism is quite different, resulting in different types of information. The AFM is now a well-established technique to study quantitatively the topography of a wide variety of materials. 
The present study shows decrease in the RMS values for Gutta-percha when exposed to 5.25% NaOCl for 1, 5, 10, 20 and 30 min and no significant alteration in the surface topography of Gutta-percha and resilon when exposed to CHX. Resilon showed no changes in the surface topography when exposed to NaOCl as well. The result of the study is consistent with the study conducted by Valois et al. indicating a deteriorative tendency of the intermediate (2.5%) and high (5.25%) NaOCl concentrations on Gutta-percha cone surface topography. 
Pang et al. detected that Gutta-percha cones soaked in 5.25% NaOCl showed a precipitate with a cuboidal crystal structure over the entire surface with particular concentration in the defective or folded area of cones. A large variety of rounded structures were detected in the deeper strata of the defective area of the Gutta-percha cones, which are lysis products of some components of Gutta-percha cones. They also showed significant effects on elongation rate. 
Isci et al. found that CHX had no effect on the surface topography, whereas NaOCl caused alteration of the surface topography of the Gutta-percha. Similarly, Seabra Pereira et al. observed that when 2% CHX was used, no topographic changes were observed with or without rinse. ,
| Conclusion|| |
Based on the results of this study, it can be inferred that 5.25% NaOCl causes severe surface topographic changes of the Gutta-percha points. There is no effect on surface topography of Gutta-percha when treated with 2% CHX. Resilon showed no alteration in surface topography when treated with either 5.25% NaOCl or 2% CHX. Thus, the study shows that 2% CHX could be a better alternative to 5.25% NaOCl for chair-side disinfection of Gutta-percha and resilon cones.
| References|| |
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|5.||Short RD, Dorn SO, Kuttler S. The crystallization of sodium hypochlorite on gutta-percha cones after the rapid-sterilization technique: An SEM study. J Endod 2003;29:670-3. |
|6.||Isci S, Yoldas O, Dumani A. Effects of sodium hypochlorite and chlorhexidine solutions on Resilon (synthetic polymer based root canal filling material) cones: An atomic force microscopy study. J Endod 2006;32:967-9. |
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Abhijith S Shetty
Department of Conservative Dentistry and Endodontics, S.D.M. College of Dental Sciences and Hospital, Sattur, Dharwad 580 009, Karnataka
Source of Support: None, Conflict of Interest: None
[Figure 1], [Figure 2]
[Table 1], [Table 2], [Table 3], [Table 4], [Table 5]