|Year : 2021 | Volume
| Issue : 3 | Page : 170-175
Comparative evaluation of sealing ability of three bioactive obturation materials: A bacterial leakage study
Meenu G Singla, Sakshi Panghal
Department of Conservative Dentistry and Endodontics, Sudha Rustagi College of Dental Sciences and Research, Faridabad, Haryana, India
|Date of Submission||15-Apr-2021|
|Date of Decision||01-Jun-2021|
|Date of Acceptance||07-Sep-2021|
|Date of Web Publication||30-Sep-2021|
Dr. Meenu G Singla
Department of Conservative Dentistry and Endodontics, Sudha Rustagi College of Dental Sciences and Research, Faridabad, Haryana
Source of Support: None, Conflict of Interest: None
Aim: The aim of this study was to evaluate and compare the sealing ability of three obturating materials used with single-cone technique: C Point/Endosequence BC sealer, gutta-percha/Endoseal MTA and gutta-percha/GuttaFlow bioseal using bacterial leakage model with Enterococcus faecalis.
Materials and Methods: Seventy-six extracted human single-rooted mandibular premolars with straight canals prepared using Hyflex CM up to 45/04 and assigned to 3 experimental groups according to the root canal filling material as Group A - C Point/Endosequence BC sealer; Group B - guttapercha/Endoseal MTA; Group C - guttapercha/GuttaFlow bioseal. Split-chamber bacterial leakage model was prepared and microleakage analysis was made every 24 h for up to 9 weeks. The presence of E. faecalis was confirmed by light microscopy and Gram staining.
Results: A survival analysis was performed using Kaplan–Meier plots and a log-rank test and it was found that Group A showed the best apical seal followed by Group C and then Group B at the end of the observational period. The difference in bacterial leakage among Group A and C versus Group B was statistically significant (P < 0.05), but there was no significant difference between Group A and Group C.
Conclusion: C Point/Endosequence BC sealer and GP/Guttaflow bioseal sealer has shown better apical seal with single-cone technique as compared to GP/Endoseal MTA.
Keywords: Enterococcus faecalis, Endoseal MTA, Guttaflow bioseal, microleakage, obturation
|How to cite this article:|
Singla MG, Panghal S. Comparative evaluation of sealing ability of three bioactive obturation materials: A bacterial leakage study. Endodontology 2021;33:170-5
| Introduction|| |
Three-dimensional obturation with the creation of bacterial tight coronal as well as the apical seal is essential for long-term success of endodontic treatment as it prohibits bacterial penetration and their by-products into the cleaned and disinfected root canal system.,
Solid core material along with root canal sealers play a major role to create an impervious seal of the root canal system. In an effort to overcome the shortcomings of conventional hydrophobic sealers (zinc oxide based, calcium oxide based, resilon, or resin based) such as higher solubility, less flowability, lack of biomineralization, and anti-bacterial property and lack of adhesion and shrinkage upon cooling properties of solid core material, i.e., gutta-percha, newer hydrophilic materials that ensure better adhesion and penetration in dentinal tubules have been introduced.
One of the advancements in endodontic obturating materials that uses a hydrophilic polymer in the root canal is the C Point system/Smartseal system (EndoTechnologies, Shrewsbury, USA). C Points are designed to expand laterally without expanding axially, by absorbing residual water from the instrumented canal space and from naturally occurring intra-radicular moisture. C Points expand nonuniformly and the extent to which the hydrophilic polymer is pre-stressed determines their expandability (i.e., the rate or extent of polymer expansion will get reduced after contact with a canal wall). Thus the sealing ability of C Points is enhanced by the nonisotropic lateral expansion which reduces the possibility of reinfection and increases the long-term success of root canal treatment.
C Points are used along with a bioceramic sealer, EndoSequence BC sealer (Brassler, USA). It is a hydrophilic, premixed, and injectable endodontic sealer that uses moisture in dentinal tubules to initiate and complete its setting reaction. It has several advantages such as biocompatibility, high pH (<12), being nonshrinkable and nonresorbable, has ease of delivery in the root canal, and the ability to form hydroxyapatite forming chemical bond with the dentin wall.,
Endoseal MTA (MARUCHI, Korea), a new pozzolan-based MTA sealer has been developed and used as a root canal filling material which has favorable properties such as ease of use, good flowability, fast setting time, and its ability to induce biomineralization the dentinal tubules. During the injection, Endoseal MTA absorbs the environmental moisture from atmospheric air and sets without the need of powder/liquid or base/catalyst mixing.
Another new bioactive obturation material, GuttaFlow bioseal (Coltene Whaledent, Inc. Switzerland), a polydimethylsiloxane (silicon)-based sealer has been introduced. It is a hydrophilic sealer which upon contact with fluids provides natural repair constituents such as calcium and silicates. According to manufacturers, it forms hydroxyapatite crystals on the surface which improves adhesion.
With the introduction of these bioactive obturating systems, it has become feasible to achieve success by using single-cone obturation technique, which is one of the recent trends in endodontics. Studies by Holland et al. and Inan et al. showed that the single cone technique exhibited better sealing than the lateral condensation technique.
As the sealing ability is a basic feature that needs to be tested and comparatively evaluated for every newly introduced root canal filling material. In the literature, several methods have been used to assess the sealing ability such as dye leakage, scanning electron microscopic evaluation, radioisotopes, and bacterial leakage. Among these techniques, the bacterial leakage model is considered the most acceptable method.
Hence, this study was done to evaluate and compare the sealing ability of these three obturating materials, i.e., C Point/Endosequence BC sealer, GP/Endoseal MTA, and GP/GuttaFlow bioseal using single cone obturation technique.
| Materials and Methods|| |
Seventy-six extracted human single-rooted mandibular premolars with straight canals and fully formed apices were selected for the study. Teeth with calcified canals, anatomical anomalies, caries/restoration below cementoenamel junction, and fractures or cracks in roots were excluded. Ethical clearance (Reference No. – SRCDSR/ACAD/2017/6037) for this study was obtained by the Institutional Ethical Committee, Sudha Rustagi College of Dental Sciences and Research, Faridabad.
Samples were collected, cleaned, and sterilized in 5.25% sodium hypochlorite (Bharat Chemical, India) for 2 weeks. Teeth were decoronated to a standardized root length of approximately 16 mm using diamond disk and then stored in distilled water before instrumentation. Working length was determined by subtracting 1 mm from the length at which a number 10 K – file was visible at the foramen. Samples were prepared till number 20 K file and then each canal was instrumented to a size 45/04 with Hyflex CM (Coltene Whaledent, Alstatten, Switzerland) rotary instruments. After each file use, canals were irrigated with 2ml of 5.25% sodium hypochlorite. After preparation, canals were irrigated with 5ml of 17% EDTA (Dental Avenue Pvt. Ltd, Mumbai, India) for 1 min to remove the smear layer. Final irrigation was done with 5 ml of distilled water and canals were dried with sterile paper points (Meta Biomed).
Samples were then randomly divided according to different root canal filling materials into three experimental groups (22 each) and two control groups (5 positive and 5 negative).
- Group A: C Point/Endosequence Bioceramic sealer (n = 22)
- Group B: Guttapercha/Endoseal MTA (n = 22)
- Group C: Guttapercha/GuttaFlow bioseal (n = 22)
- Group D: Positive control (no obturation) (n = 5)
- Group E: Negative control - guttapercha/AH Plus (n = 5).
Sealers in Group A, B, C were mixed according to the manufacturer's instructions and applied into the canal using a lentulospiral. A matched tapered single cone of size 45/04 (C Point in Group A; gutta-percha in Group B and C) were coated with respective sealer and were placed into the root canal to the full working length. C-Points were cut with scalepal with the aid of smart gauge and excess gutta-percha was sheared off with a hot instrument. Samples in the positive control group (Group D) received no root canal fillings, while in the negative control group (Group E), they were obturated with a single cone gutta-percha of size 45/04 and AH Plus sealer.
Except for the apical 2 mm and the occlusal table, all teeth in the test (Group A, B, C) and positive control (Group D) groups received three coats of clear nail polish while in negative control group (Group E), three coats of clear nail polish covered 100% of the root surface. Teeth were incubated in 100% humidity at 37°C for 3 weeks before the introduction of Enterococcus faecalis (ATCC 29212 strain).
Bacterial leakage model preparation
The bacterial leakage model used in this study was the modification of the model used by Khayat et al. The tapered ends of 2-ml Eppendorf plastic tubes (Fisher Scientific, Waltham, Massachusetts, United States) were resected and the teeth were inserted with the apex pointing down. Hot glue was then used to seal the junction between the tube and the extruded root [Figure 1] and [Figure 2]. Three coats of clear nail polish were placed over the set glue.
|Figure 1: Diagrammatic illustration of bacterial leakage model which was used in this study|
Click here to view
All tooth-tube assemblies were sterilized in ethylene oxide gas chamber and the glass vials containing phenol red broth (HiMedia Laboratories Pvt. Ltd., Mumbai) were autoclaved. The root of each tooth was immersed approximately 2 mm into the phenol red broth. The sterile broth and mounted teeth were observed for 5 days to ensure no contamination before inoculation. From a stock culture of E. faecalis strain, subculture was made onto a plate containing Brain Heart Infusionagar (HiMedia Laboratories Pvt. Ltd., Mumbai). Then, a bacterial suspension of E. faecalis in 0.5 McFarland concentration was prepared. This was incubated at 37°C for 24 h. Serial dilution (1:10) was carried out. Eppendorf tube with embedded roots was inoculated with 10μl of diluted E. faecalis suspension using sterile micropipette. The top chambers were reinoculated after every 7 days for 9 weeks.
The broth was observed daily for 9 weeks for color change (indicative of microleakage). When the broth color changed, Gram staining was performed. First, Crystal violet stain was applied to a heat-fixed smear which stained all cells purple color. Next, Gram's iodine was added to set or stabilize stains or dyes. After that, decolorizing agent acetone was added. Finally, a secondary counterstain, safranin was added. Following this, light microscopy was performed at ×10 and the presence of blue color cocci in short chains and clusters conferred the presence of E. faecalis.
Collected data were subjected to statistical analysis using Statistical Package for Social Sciences (version 16, SPSS Inc., Chicago, IL, USA). Survival analysis was the statistical method of choice to analyze the results. A survival analysis was performed by using Kaplan–Meier plots and a Log-rank test to assess the significance of the differences among the groups. The occurrence of microleakage was considered as “event” for the analysis. The level of significance was set at 0.05.
| Results|| |
Results showed that all the root canal filling materials exhibited microleakage. Survival curves are shown in [Figure 3]. Survival time (time without microleakage) for Group A was longer than that of Group C which was furthermore than that of Group B. The median survival time of Group A before microleakage was 8 weeks, of Group 2 was 5 weeks; of Group 3 was 6 weeks [Table 1].
|Figure 3: Plot of cumulative survival proportion against time for each test material group|
Click here to view
Survival analysis and Log-rank test found that the difference in bacterial leakage among Group A and C versus Group B was statistically significant but there was no significant difference between Group A and Group C, χ2 (2) =6.030, P = 0.049.
The KaplanMeier Survival probability of Group A was highest, i.e., between 0.5 and 0.6 followed by Group C - between 0.4 and 0.5 and then Group B - between 0.1 and 0.2.
| Discussion|| |
Three-dimensional root canal obturation is among the most important steps in root canal treatment to decrease the microleakage and to achieve long-term success.
Mandibular premolars with single canals were selected for this study as they have oval-shaped canals, providing space between the rounded gutta-percha and the root canal walls, such space will need a greater amount of sealer between the filling material and root canal walls, which requires the use of a sealer with optimum sealing ability.
For standardization, the teeth were decoronated and the length of all roots were fixed to 16 mm, as it was found by Metzger et al. and Mozini et al. that the length of the filling material would affect the rate of bacterial leakage. Furthermore, the volume of the canals was standardized to the same taper and size by the use of Hyflex CM files (45/4%) for biomechanical preparation.
The bacterium to be selected as the leakage marker should preferably be an endodontic pathogen, and easy to cultivate. So, E. faecalis was chosen as the bacteriological marker in this study which is a nonfastidious, easy-to-grow facultative anaerobic bacterium of significant clinical importance. E. faecalis is a persistent organism that makes up a small proportion of the flora in untreated canals while it is commonly found in a high percentage in root canal failures cases. In such situations, it can survive in the root canal as a single organism or as a major component of the flora.
The results of the negative control group in this study were 0% as none of the five teeth showed any leakage. Their broth remained clear all throughout the study period. This proved that the seal between the two chambers of the system was efficient. While all the samples in the positive control group without obturation showed leakage within 24 h.
Group A (C Point/Endosequence BC sealer) showed the best apical seal followed by Group C (GP/Guttaflow bioseal) and then Group B (GP/Endoseal MTA). The results in the present study are in accordance with the findings reported by El-Sayed et al. and Hegde and Arora; which showed that the hydrophilic Smart-Seal system (also known as C Points) provided better sealing ability compared to other single-cone obturation systems., In a study by Mobark et al., it was found that C Point/Endosequence BC sealer showed less bacterial leakage as compared to GP/Endosequence BC sealer. They attributed it to the expansion property possessed by the C Point cones, where the cones are designed to expand laterally without expanding axially. This postsetting expansion shows an approximately 14% expansion after 20 min which could provide better sealing and adhesive properties, as it decreases the gaps and voids found between the main cone and the root canal walls.
Furthermore, the better sealing of Endosequence BC sealer with C Point cones could also be attributed to the slow setting time of the sealer which provides more time for the expansion of the C Points pushing the sealer towards dentinal walls, so better filling of the canals irregularities. It has been shown that an apatite layer is formed due to the release of calcium and hydroxyl ions from the BC sealer. The formation of this interfacial layer develops a chemical bond between the sealer and dentinal walls decreasing the marginal leakage and gaps. Moreover, BC Sealer's extremely small particle size (2 μm) and hydrophilic nature allow it to flow into all aspects of the canal anatomy.
In contrast to our findings, Rajkumar et al. found that Propoint (C-point) showed more microleakage as compared to GuttaFlow and Thermafil with AH Plus sealer. The difference in results might be because we have used Endosequence BC sealer with C Points whereas in the study by Rajkumar et al., propoints were used without any sealer. Another reason for the difference in results could be due to different methodologies used in both studies. In this study, we have used bacterial leakage model whereas in their study dye penetration method was used.
Group C (GP/GuttaFlow bioseal) showed slightly more bacterial microleakage in comparison to Group A (C Point/Endosequence BC sealer) and the difference was not statistically significant. This slight difference in results might be due to the fact, GuttaFlow bioseal sealer was used with GP which does not have any expansion property like C Points of Group A. Another reason could be the higher alkaline pH of Endosequence BC sealer (11–12) as compared to GuttaFlow bioseal (7.9) that might have been responsible for the better antibacterial property of Endosequence BC sealer contributing to better results of C Point/Endosequence BC sealer.
In literature, only one study by Gandolfi et al. evaluated the sealing ability (using fluid filtration method), calcium release and alkalinizing activity (pH) of GuttaFlow bioseal, GuttaFlow 2 and Roekoseal Automix and it was concluded that GuttaFlow bioseal showed best sealing ability though not statistically significant. According to Gandolfi et al., the pH value of approximately 8 of GuttaFlow bioseal suggests antibacterial activity which could be related to its bioactive glass composition. Increase in hydroxyl ions leads to low concentrations of bacteria such as the E. faecalis.
Group B (GP/Endoseal MTA sealer) showed leakage in the maximum number of samples (17 out of 20) in 9 weeks. Despite various favorable properties of Endoseal MTA such as larger setting expansion, biomineralization, good flow,, Group B (GP/Endoseal MTA sealer) showed significantly more microleakage as compared to Group A and Group C. In literature, no study has been found that directly compares bacterial leakage of Endoseal MTA with GuttaFlow bioseal and Endosequence BC sealer. Only one study by Hwang et al. had compared the bacterial leakage of Endoseal MTA with GuttaFlow, which is a predecessor of GuttaFlow bioseal. They had compared the bacterial leakage of GP/GuttaFlow (single cone technique) and GP/Endoseal MTA with ultrasonic activation through GP. They found that Endoseal MTA showed less bacterial leakage than GuttaFlow. The results of this study are in contrast with our findings. The better results of GuttaFlow bioseal than Endoseal MTA in our study might be because we have used advanced version of GuttaFlow, i.e. GuttaFlow bioseal which have better properties as compared to GuttaFlow. Another reason for the difference in results of Endoseal MTA could be the use of ultrasonic condensation for Endoseal MTA by Hwang et al. which was not used in our study. They emphasized that the increase in the flowability of Endoseal MTA caused by ultrasonic vibration makes the canal obturation procedure easier and the filling of complex anatomical variations more complete. This was supported by a study by Kim et al., who compared the filling quality of Endoseal MTA + single-cone with ultrasonic activation and Endoseal MTA + single-cone using micro-computed tomography. They found that Endoseal MTA + single-cone with ultrasonic activation obtained a better filling quality with fewer voids as compared to Endoseal MTA with single-cone technique only.
In the literature, some studies, have been reported in which the sealing ability of Endoseal MTA is compared with various other sealers. Kim et al., found that Endoseal MTA showed inferior sealing ability when compared with resin sealer, AH 26. They attributed it to low flowability and low surface activity of Endoseal MTA as compared to AH Plus. Another study by Kim et al. showed that despite the favorable properties of Endoseal MTA such as fast setting time and larger setting expansion than that of AH Plus, Endoseal MTA showed similar sealing ability as that of AH Plus, which might be associated with higher solubility of Endoseal MTA (0.7%) as compared to AH Plus (0.06%).
| Summary and Conclusion|| |
- All the experimental groups did not totally prevent bacterial leakage and showed progressive leakage with time
- Out of three experimental Groups, C Point/Endosequence BC sealer exhibited the best sealing ability followed by GP/GuttaFlow bioseal sealer and GP/Endoseal MTA sealer. The difference in the bacterial leakage was statistically significant between GP/Endoseal MTA sealer versus C Point/Endosequence BC sealer and GP/GuttaFlow bioseal sealer but there was no significant difference between C Point/Endosequence BC sealer and GP/GuttaFlow bioseal.
Financial support and sponsorship
Conflicts of interest
There are no conflicts of interest.
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[Figure 1], [Figure 2], [Figure 3]