Year : 2021 | Volume
: 24 | Issue : 2 | Page : 195--198
Effect of root dentin conditioning using different chelating agents on pushout bond strength of MTA-fillapex and bioroot RCS: An in vitro study
Jesline Maria Jose, EM Manju Krishna, S Maneesh Ahamed, Robin Theruvil, Jain Mathew, Saira George
Department of Conservative Dentistry and Endodontics, St. Gregorios Dental College, Ernakulam, Kerala, India
Dr. Jesline Maria Jose
Department of Conservative Dentistry and Endodontics, St. Gregorios Dental College, Ernakulam - 686 681, Kerala
Context: The success of endodontic therapy depends on proper biomechanical preparation and obturation.
Aim: To evaluate and compare the pushout bond strength (POBS) of MTA Fillapex (MF) and BioRoot RCS (BRCS) sealers in endodontically treated teeth with different irrigants-5.25% Sodium hypochlorite (NaOCl), 17% ethylenediaminetetraacetic acid (EDTA) and 0.2% Chitosan.
Materials and Methods: 60 premolars were divided into three groups. Each group was then subdivided into A and B. The three groups were Group 1A: 17% EDTA + 5.25% NaOCl with MF sealer (n = 10); Group 1B: 17% EDTA + 5.25% NaOCl with BRCS sealer (n = 10); Group 2A: 0.2% Chitosan + 5.25% NaOCl with MF sealer (n = 10); Group 2B: 0.2% Chitosan + 5.25%NaOCl with BRCS sealer (n = 10); Group 3A: 5.25% NaOCl + MF sealer (n = 10); and Group 3B: 5.25% NaOCl + BRCS sealer (n = 10). After obturation, they were sectioned horizontally (1.5 mm thick). The POBS was studied using a universal testing machine (Autograph AG-1). The sample size was calculated using the statistical package G * Power (3.1.5).
Results: It was found that the POBS of BRCS was higher when the root canal was irrigated with 0.2% Chitosan + 5.25% NaOCl. Thus, Group 2B showed significantly higher POBS than Group 2A.
Conclusion: The irrigation regimen of Chitosan with NaOCl was found to have better debriding effect on the root canal. Of the two sealers, BRCS showed the higher bond strength values than MF.
|How to cite this article:|
Jose JM, Manju Krishna E M, Ahamed S M, Theruvil R, Mathew J, George S. Effect of root dentin conditioning using different chelating agents on pushout bond strength of MTA-fillapex and bioroot RCS: An in vitro study.J Conserv Dent 2021;24:195-198
|How to cite this URL:|
Jose JM, Manju Krishna E M, Ahamed S M, Theruvil R, Mathew J, George S. Effect of root dentin conditioning using different chelating agents on pushout bond strength of MTA-fillapex and bioroot RCS: An in vitro study. J Conserv Dent [serial online] 2021 [cited 2022 Jan 16 ];24:195-198
Available from: https://www.jcd.org.in/text.asp?2021/24/2/195/327857
The success of the root canal treatment is attributed to a proper biomechanical preparation. Studies have shown that the large areas of root canal walls remain untouched despite using the hand and rotary instrument during the canal preparation. This shows the importance of disinfecting the root canal system by chemical means. To achieve this goal, irrigating solutions must be used in a specific sequence.
During mechanical preparation of the canal, a smear layer is formed on the instrumented canal walls and debris on the uninstrumented walls. Studies have shown that these may impede sealer penetration into the dentinal tubules, thereby compromising the seal required during obturation.
Sodium hypochlorite (NaOCl) is the most widely used irrigant in endodontics. It is used in combination with chemical agents such as ethylenediaminetetraacetic acid (EDTA) and Chitosan which aid in the elimination of the smear layer and debris.
EDTA is a polyaminocarboxylic acid that is water soluble in neutral or alkaline pH. It is used in endodontics because of its chelating property whereby it interacts with calcium ions present in dentin to form soluble chelates of calcium.
Chitosan is a natural polysaccharide, which has attracted the attention of dental research because of its biocompatibility, biodegradability, bioadhesion, and lack of toxicity. It has a high chelating ability for various metal ions in acidic conditions and has been used widely for the removal of metal ions in different industrial areas. Chitosan is obtained by the deacetylation of chitin, which is found in crab and shrimp shells.
The first sealer based on tricalcium silicate was MTA Fillapex (MF) (Angelus, Londrina, Brazil). MF is stable when used with warm vertical compaction technique. The other tricalcium silicate-based sealer is Bioroot RCS (BRCS) (Septodont, St Maure de Fosses, France). Its sealer properties change when heated, and hence, it can be used only with single cone obturation.
Unlike other bond strength tests like micro tensile bond strength and micro shear bond strength, the pushout bond strength (POBS) test is particularly suitable and extensively used in the literature for the evaluation of bond strength of sealers to the root canal dentin.
The POBS test evaluates the interfacial bond strength of a restorative material to root canal dentin. It provides information about the adhesiveness as well as helps to understand the resistance of the tested material to dislodgement, that is how well the material binds to the tooth structure. It is an efficient and reliable technique and is easy to align the samples for testing. It is less sensitive to small variations among specimens and to the variation of stress distribution during the load application. Another advantage of this method is that it allows root canal sealers to be evaluated even when bond strengths are low. Hence, in this study, the bond strength between the root canal sealers to the radicular dentin was evaluated by POBS using the universal testing machine.
The aim of this study was to evaluate and compare the POBS of sealers MF and BRCS during obturation while treating teeth with different irrigation regimes namely-5.25% NaOCl only; 17% EDTA + 5.25% NaOCl, and 0.2% Chitosan + 5.25% NaOCl.
The null hypothesis tested was that there is no significant difference in the POBS of sealers MF and BRCS during obturation using different irrigation regimes.
Materials and Methods
Sample size estimation
The number of samples included in this study was based on the POBS of MTA to root canal dentin treated with different irrigants. Based on this, the sample size was estimated at a 95% confidence interval and with the power of 80%, which resulted in 10 samples per group. The sample size was calculated using statistical package G * Power (3.1.5) SPSS Software, IBM India.
Sixty single-rooted teeth were selected. Soft-tissue fragments and calcified debris on the specimens were removed using ultrasonic scalers. The specimens were stored in a solution of 0.2% sodium azide (Sigma-Aldrich, Steinheim, Germany) at 4°C until use.
The teeth were decoronated using a diamond disc (Horico, Berlin, Germany). Working length was established by inserting #10 K file (Mani Inc., Tochigi Ken, Japan) into each root canal until it was visible at the apical foramen using magnifying loupes and then subtracting 1 mm from the recorded length. The specimens were divided randomly into three groups of 20 teeth each, based on the irrigation regimen and each group was further divided into two subgroups A and B of 10 teeth each, based on the sealers used.
The irrigation regimen was as follows:
Group 1A: 17% EDTA + 5.25% NaOCl with MF sealer (n = 10)Group 1B: 17% EDTA + 5.25% NaOCl with BRCS sealer (n = 10)Group 2A: 0.2% Chitosan + 5.25% NaOCl with MF sealer (n = 10)Group 2B: 0.2% Chitosan + 5.25% NaOCl with BRCS sealer (n = 10)Group 3A: 5.25% NaOCl + MF sealer (n = 10) (Control group)Group 3B: 5.25% NaOCl + BRCS sealer (n = 10) (control group).
The root canals were cleaned and shaped using the ProTaper system (DENTSPLY Sirona Endodontics, Tulsa, OK, USA) to size F3. Irrigation was performed using a 27 G side vented needle (Vista Dental Inc., Racine, WI, USA), which was inserted 1 mm short of the working length. After the final irrigation, the canals were dried with paper points (DENTSPLY Sirona Endodontics).
The teeth were obturated using F3 gutta-percha using single cone technique for MF and BRCS. Obturated roots were radiographed in the buccolingual and mesiodistal directions to ensure that the canals were without voids. All the teeth were stored at the room temperature for 1 week to allow complete setting of BRCS and MF sealers. Sufficient number of teeth was selected so that samples with voids were discarded.
Pushout bond strength measurement
Each root was embedded in cold cure acrylic (DENTSPLY India, Gurgaon, Haryana, India). The middle third was sectioned horizontally using a hard tissue microtome (Leica Biosystems, Nussloch, Germany) with continuous water cooling to obtain a slice of 1.5 mm thickness. The root canal diameter as well as the height of each slice was recorded using a digital caliper. The adhesion surface area was calculated by the following equation:
Adhesion surface area (mm2) = D1 + D2/2 × п × H
Where “D1” and “D2” are the largest and smallest canal diameter, respectively.
“п” is the constant 3.14, “H” is the thickness of the root slice.
The pushout test was performed using a universal testing machine (Instron, Norwood, MA, USA) [Figure 1a]. The force applied was in the apicocoronal direction at a crosshead speed of 1 mm/min using a stainless steel plunger of 0.6 mm, positioned such that it contacted only the filling material. The maximum force (F) applied at bond failure was recorded in Newton (N).
The POBS was calculated in Megapascal (MPa) using the following formula:
POBS (MPa) = Force (N)/Adhesion surface area (mm2)
The data of the POBS of BRCS and MF to root canal walls is presented as means ± standard deviation.
Statistical analysis was performed using the SPSS Statistics version 20.0 software (IBM Corp, Armonk, NY, USA). POBS data were analyzed using the one-way analysis of variance with the post hoc Tukey test significant difference test. The Chi-square test was performed for the analysis of the bond failures. P < 0.05 was considered to be statistically significant (95% confidence level).
The highest POBS value was for Group 2B (46.64 ± 1.10) and the least value was for Control Group 3A (23.59 ± 0.90). In both Group 1 and Group 2, subgroups having BRCS (Group 1B and Group 2B) showed more POBS mean value compared to subgroups with MF (Group 1A and 2A). There was statistically significant difference between all the groups.
Nygaard Ostby was the first to introduce chelating agents in endodontics. Chelating agents decalcified dentin by combining with calcium ions of the tooth. They have been reported to remove the smear layer from the root canal.
In literature, only a few studies have evaluated the POBS of modern bioceramic sealers such as BRCS and MF on chelating activity of Chitosan and EDTA.
This in vitro study evaluated the POBS of BRCS and MF in root canal dentin when irrigated using different chelating agents, namely 0.2% Chitosan and 17% EDTA.
In the current study, the POBS of groups with BRCS was significantly higher than the respective groups with MF, irrespective of the chelating agent. This is in conjunction with the findings of Neelakantan et al.
The lower pushout strength of control groups 3A and 3B could be attributed to the inferior smear layer removal property of NaOCl as well as NaOCl's interaction with calcium silicate cements, both of which affect adhesion of sealers to the canal dentin.
EDTA imparts a negative influence on the hydration properties of calcium silicate cements because of its acidic nature. EDTA causes dissolution of the binding phase of the cement. Thus inhibiting adhesion to materials. This occurs if the final rinse is inadequate and the residual EDTA may chelate with the calcium ions from tricalcium silicate cement during hydration, disturbing the formation of hydrated products. Hence, Groups 1A and 2A exhibited poor bond strength than Groups 2A and 2B.
The 0.2% Chitosan solution was able to remove the smear layer and promote superior cleaning of the root canal walls than 17% EDTA. Chitosan acts on the inorganic portion of the smear layer favoring its removal by the formation of complexes with metal ions due to adsorption, ionic exchange, and chelation and is responsible for the elimination of dentin calcium ions. Thus, Groups 2A and 2B had the capacity to remove smear layer more effectively than Groups 1A and 1B. Mathew et al. concluded that Chitosan is an effective chelating agent and can be considered as a less invasive alternative to 17% EDTA.
Although MF has a good sealing ability and is biocompatible, very few studies, are available regarding its sealing and dentinal tubule penetration. Camilleri evaluated the sealing ability of MF and Pulp Canal sealer and reported that the sealing ability of both sealers was comparable.
BRCS (Septodont, St Maure de Fosses, France) is also based on tricalcium silicate. In the current study, BRCS was condensed using hand pluggers because studies have shown that manual compaction resulted in more densely obturated root fillings with superior marginal adaptation.
Pane et al. concluded that pushout tests are used as a measure of the bond strength of root canal filling materials to the root dentin. This test results in a shear stress at the dentin-cement interface, which is comparable with the stress in clinical conditions. In this study, the dentin discs of 1.5 mm were used. However, the use of thicker discs seemed to increase the area of friction and led to an over estimation of the bond strength.
The present study provides the information regarding the effect of relatively new chelating agent; 0.2% Chitosan on the dislodgment resistance of new calcium silicate based sealers.
The limitation of this study is the in vitro experimental setup, and moreover, the dentin slices for POBS evaluation were obtained only from the middle third of the root.
The results of this study showed that there was an effect on irrigating with chelating agents like 0.2% Chitosan and 17% EDTA on the POBS of bioceramic sealers, namely BRCS and MF on the root dentin. Hence, the null hypothesis should be rejected.
The POBS of BRCS and MF was influenced by chelating agents such as 0.2% Chitosan and 17% EDTA. The irrigation regimen of Chitosan with NaOCl was found to have better POBS of BRCS on the root canal. Of the two sealers, BRCS showed the higher bond strength values than MF.
Within the limitations of this study, it can be concluded that the use of chelating agents increased POBS of calcium silicate-based sealers, influenced by their properties and various dentin surface treatments.
All authors contributed equally to the work. Dr. Manju Krishna, Dr. Jesline Maria Jose, Dr. S. Maneesh Ahamed, conceived and designed the study, conducted the research and wrote the manuscript. Dr. Jain Mathew and Dr. Robin Theruvil guided while planning and conducting the study. Dr. Saira George analyzed the data and edited the manuscript. All authors read and approved the final manuscript. None of the authors had a conflict of interest. The laboratory analysis using UTM machine was done at the Dept. of Polymer Sciences and Rubber Technology, CUSAT, Kerala.
Financial support and sponsorship
Conflicts of interest
There are no conflicts of interest.
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