| Abstract|| |
Aims: The aim of the following study was to evaluate the percentage and average depth of epiphany sealer penetration into dentinal tubules among the coronal, middle and apical thirds of the root using the confocal laser scanning microscopy (CLSM).
Materials and Methods: A total of 10 maxillary central incisors were prepared and obturated with Resilon-Epiphany system. Sealer was mixed with fluorescent rhodamine B isothiyocyanate dye for visibility under confocal microscope. Teeth were cross-sectioned into coronal, middle and apical sections-2 mm thick. Sections were observed under CLSM. Images were analyzed for percentage and average depth of sealer penetration into dentinal tubules using the lasso tool in Adobe Photoshop CS3 (Adobe systems incorporated, San jose, CA) and laser scanning microscopy (LSM 5) image analyzer.
Statistical Analysis Used: One-way analysis of variance with Student Neuman Keuls post hoc tests, Kruskal-Wallis test and Wilcoxon signed-rank post hoc tests.
Results: The results showed that a higher percentage of sealer penetration in coronal section-89.23%, followed by middle section-84.19% and the apical section-64.9%. Average depth of sealer penetration for coronal section was 526.02 μm, middle-385.26 μm and apical-193.49 μm.
Conclusions: Study concluded that there was higher epiphany sealer penetration seen in coronal followed by middle and least at apical third of the roots.
Keywords: Confocal microscope; epiphany; monoblock; Resilon
|How to cite this article:|
Ravi S V, Nageswar R, Swapna H, Sreekant P, Ranjith M, Mahidhar S. Epiphany sealer penetration into dentinal tubules: Confocal laser scanning microscopic study. J Conserv Dent 2014;17:179-82
|How to cite this URL:|
Ravi S V, Nageswar R, Swapna H, Sreekant P, Ranjith M, Mahidhar S. Epiphany sealer penetration into dentinal tubules: Confocal laser scanning microscopic study. J Conserv Dent [serial online] 2014 [cited 2019 Nov 20];17:179-82. Available from: http://www.jcd.org.in/text.asp?2014/17/2/179/128056
| Introduction|| |
Successful endodontic therapy involves instrumentation of the root canal to produce a surface free from debris and organic matter and obturation to achieve an optimally-sealed canal.  Gutta-percha has been universally accepted as the gold standard for root filling materials and the material against which others are compared. However, gutta-percha even with conventional sealers is not capable of preventing leakage. Hence materials with adhesive properties are advocated. ,,
The ability of root canal fillings materials to penetrate into dentinal tubules is regarded as a relevant aspect in prevention of reinfection of the dentinal tubules.  A relatively new material, Resilon-Epiphany system promises such tubular adhesion.
Scanning electron microscopy (SEM) has been a commonly used testing method to evaluate sealer-dentin interface. However, this technique needs a special processing which would lead to shrinkage of the lower half of the hybrid layer. 
This study evaluated the percentage and average depth of dentinal tubule sealer penetration in the coronal, middle and apical thirds of teeth obturated with the Resilon-Epiphany obturation system using confocal laser scanning microscopy (CLSM).
| Materials and Methods|| |
Ten maxillary central incisors were collected from the Department of oral surgery and cleaned of soft tissue debris and calculus with a bur. The teeth were disinfected using 2.5% sodium hypochlorite (NaOCl) solution (Prevest denpro Ltd, India) for half an hour and then stored in physiological saline. Access cavities were prepared using Endo-Access bur (Dentsply-Maillefer, Ballaigues, Switzerland). A K-file (Mani Inc., Japan) was placed in the canal and a periapical radiograph was taken to determine working length. All the teeth were enlarged using ProTaper rotary files and X-smart, endomotor (Dentsply-Maillefer, Ballaigues, Switzerland) up to F3 file size. Along with this instrumentation, irrigation was done between uses of each file, delivering 10 ml of 3% NaOCl (Prevest Denpro Ltd., India). After the instrumentation was completed, all the specimens received a final flush with a 10 ml of neutralized 17% ethylenediaminetetraacetic acid (EDTA), (Dent Wash-Prime Dental, India) followed by 10 ml of NaOCl to remove the smear layer. After that, 10 ml of sterile water was used to remove any remaining NaOCl residue. The canals were dried with sterile paper points (Dentsply-Maillefer, Ballaigues, Switzerland).
To apply the epiphany primer, (Pentron Clinical Technologies, LLC Wallingford, CT, USA) a paper point was placed to working length and primer was applied to the paper point, letting the point wick the primer to the apex. To facilitate fluorescence under Confocal Laser Microscopy, Epiphany sealer was mixed with Rhodamine B Isothiyocyanate fluorescent dye (maximum absorption = 570 nm, maximum emission = 720 nm) to an approximate concentration of 0.1%. A mixture of fluorescent dye and sealer (Pentron Clinical Technologies, LLC Wallingford, CT, USA) was placed along the entire length of the canal using a K-file in anticlockwise direction. Resilon size 30, 0.06 taper cones were selected as master cones and the fit was verified by placing it to the working length. Canals were obturated using lateral condensation technique along with the use of Resilon accessory cones (Pentron Clinical Technologies, LLC Wallingford, CT, USA). Excess of Resilon were removed using heated instrument and vertically compacted at the orifices using hand pluggers. The material at the orifice was light cured for 40 s. Radiographs were taken to ensure that no voids were present. Access cavities were sealed with Cavit (3M ESPE MN, U.S.A).
Preparation of specimen for microscopy
Teeth were sectioned at the mid-point of the coronal, middle and apical third of each root. This resulted in 3 groups of 10 samples each Group 1: Coronal, Group 2: Middle, Group 3: Apical. All sections were polished with Arkansas stone using running tap water as a lubricant to smoothen the surface. Samples were examined with a Zeiss Pascal laser scanning microscopy (LSM) (Carl Zeiss, Germany). CLSM images were recorded in the fluorescent mode. Images were recorded at × 10, with an oil immersion. Each × 10 sample was evaluated for a consistent fluorescent ring around the canal wall indicating sealer and root dentin. Sealer penetration of any distance into the dentinal tubules was measured by Adobe Photoshop CS3. First, each sample image was imported into photoshop; outlined using the lasso tool and the circumference of the canal was measured. Next, areas along the canal walls in which sealer penetrated into dentinal tubules to any distance were measured using the same method. The outlined distances were divided by the canal circumference to calculate the percentage of any canal wall sealer penetration in that section as shown in [Figure 2]b and c. The 10% for each group were statistically analyzed by one-way analysis of variance with Post hoc Student-Neumann-Keuls test for multiple comparisons. Using ruler tool on the CLSM image recorder software, the depth of sealer penetration was measured at four standardized points on each section. The canal wall served as the starting point and sealer penetration was measured to maximum to a maximum depth of 1,000 μm the outer limit of sealer penetration visible within the microscope field as shown in [Figure 2]a. These data points were averaged to obtain a single observation for each section. Due to the measurement limitation of 1,000 μm with the CLSM, nonparametric tests were used to analyze the censored data. The Kruskal-Wallis test for significance between groups and post hoc Wilcoxon signed-rank tests for pair-wise comparisons were conducted. All the statistical analysis was performed using the software SPSS-15 (SPSS Inc. Chicago, IL).
| Results|| |
A consistent fluorescent sealer ring was seen around the canal in all 10 × sections. All sections were calculated for percentages and average depths of sealer penetration.
Percentage of sealer penetration
In coronal sections an average value of 89.23% of sealer penetration for 10 coronal sections was derived whereas mid-root sections an average value of 84.19% of sealer was derived, which was similar to coronal sections. But apical sections an average value of 64.9% of sealer penetration was derived, which was very much lower compared to coronal and mid-root sections. All the values were applied to statistical analysis. The statistical results were as follows as shown in [Table 1].
|Table 1: Comparison of percentage depth of sealer penetration between three groups by One way analysis of variance and Newman-Keuls post hoc test|
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One-way analysis of variance found a significant effect for percentage of sealer penetration among the groups (P < 00.1). Student Neuman Keuls post hoc tests indicated statistically significant difference in percentage of sealer penetration between coronal, middle and the apical sections.
Average depths of sealer penetration
An average value of 512.03 μm of sealer penetration was derived from coronal sections whereas an average value of 385.26 μm of sealer penetration was derived from mid-root sections, which was lesser than coronal sections. However apical sections had the least with an average value of 193.49 μm of sealer penetration. All the values were applied to statistical analysis. The statistical results were as follows as shown in [Table 2].
|Table 2: Comparison of average depth sealer penetration between three groups by Kruskal Wallis and Wilcoxon post hoc tests|
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The kruskal-Wallis test found a significant effect for the average depth of sealer penetration among groups (P < 0.002) and Wilcoxon signed-rank post hoc tests found statistically significant difference between three groups (P < 0.05).
| Discussion|| |
It has been observed that, regardless of the chemical composition of endodontic sealers, no root canal sealer has all the ideal properties and most leak with time, either through poor initial adaptation to the canal walls or due to solubility and disintegration of the sealer. Although gutta-percha has many desirable properties, it does not bond to the internal tooth structure, resulting in the absence of a complete seal. This produces a poor barrier to bacterial microleakage and is considered to be one of the weakest points in root canal therapy. Many attempts have been made to resolve the problem through using different sealers and variations in obturation techniques. These methods have reduced microleakage to a certain degree but have still failed to eliminate the problem. 
The concept of adhesive dentin bonding procedures for endodontic treatment has been previously investigated. It was found that resin-based adhesive materials may have the potential to reduce the degree of microleakage from both apical and coronal directions of the root canal system.
Resilon looks and handles like gutta-percha and is therefore called Resin-Percha.  The penetration into deninal tubule of the self-etching primer and composite sealer may prevent shrinkage of the resin filling away from the dentine wall and aid in sealing the roots.
These materials have been shown to be biocompatible, non-cytotoxic and non-mutagenic and have been approved for endodontic use by the Food and Drug Administration of the United States. 
Epiphany bonds both to primer and Resilon cones forming a Resilon monoblock system, which has good adaptation. As Resilon is applied using a methacrylate-based sealer to self-etching primer-treated root dentin, it contains two interfaces, one between the sealer and primed dentin and the other between the sealer and Resilon and hence may be classified as a type of secondary monoblock. Resilon-filled root canals have been found to be better than conventionally gutta-percha - filled canals in resisting bacterial leakage and improving the fracture resistance of endodontically treated teeth. ,
A volume of 3 ml of 17% EDTA for 3 min, followed by a 3 ml rinse with 1% NaOCl, has proved to be sufficient to achieve complete smear layer removal which is necessary for adequate bonding. However, manufactures warn against using NaOCl as the final rinse after removal of the smear layer. They recommend 6% NaOCl followed by 17% EDTA with a final rinse with sterile water or Chlorhexidine. ,
Several test methods have been used to evaluate the sealing ability of obturated root canals, like Linear measurement of tracer dye or isotope), Fluid filtration models, Bacterial leakage models, Electro-chemical models, Spectrophotometry and SEM. However a single conclusive, advocative method, technique, or material over any other has still not been reached. The variety of evaluative methodologies and their assessment parameters are major reasons for such disagreement. 
SEM has been a commonly used testing method to evaluate sealer-dentin interface. However, this technique needs a special processing of the specimens. The microscopic images would thus show reduced thickness of the hybrid layer as processing would lead to shrinkage of the lower half of the hybrid layer where as in confocal microscope no such processing is needed and possibility of evaluating the different bonding agents is that can be kept humid during the examination which results in decreased risk of shrinkage artifacts. 
Measurement of sealer penetration into the dentinal tubules was the main parameter in this study. Epiphany sealer was labeled with rhodamine B isothiyocyanate fluorescent dye to facilitate fluorescence under confocal laser microscopy. Since there is no specific methodology devised for incorporating dyes into dental materials in the literature,  current study tried to maintain standardization for the amount of dye to be incorporated-for 10 parts of sealer, 1 part of dye powder was taken and mixed manually so that approximate concentration of 0.1% of dye is maintained. The amount of dye used is so less that it would not alter the properties of sealer. 
Sealer penetration was measured in two different ways to get accurate results. Firstly, sealer penetration of any distance was measured by using Adobe Photoshop CS3. Secondly, the average depth of sealer penetration was measured at four different standardized points using ruler tool in the LSM 5 image analyzer and mean value was taken.
The results showed that higher percentage and average depth of sealer penetration was found in the coronal section followed by middle section and the apical section This might be explained by a significantly higher density of dentinal tubules with greater diameters in the root's coronal third (about 40,000) compared with middle and apical thirds (about 14,400).
The results were consistent with the studies conducted by Chadha et al., Patel et al., Gharib et al. and Chandra et al., wherein they found lower average depth of sealer penetration in the apical sections compared with middle and coronal sections and also lower percentage of sealer penetration in the apical sections. ,,,
Pawinńska et al. with SEM analysis found good adhesion of epiphany sealer to the canal walls with visible tags in dentine tubules. Good adherence was also found of epiphany to Resilon and Resilon to root dentin and according to Fathia et al. Resilon/Epiphany sealer had better apical sealing ability than gutta-percha/AH-Plus sealer. ,
Within the parameters of the study, it concludes that epiphany sealer penetrates higher in coronal thirds of root compared to middle and apical thirds of the root. These results can be attributed to better adaptation of the obturating material to the root canal.
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S V Ravi
Department of Conservative and Endodontics, K.M.C.T Dental College, Manassery, Calicut - 673 602, Kerala
Source of Support: None, Conflict of Interest: None
[Table 1], [Table 2]