Comparative Evaluation of Peroxide Release during Non-Vital Bleaching Using RMGIC, MTA and Biodentine as Intracoronal Barriers: An in Vitro Study

International Journal of Dental Science and Innovative Research (IJDSIR) IJDSIR : Dental Publication Service Available Online at:www.ijdsir.com Volume – 8, Issue – 3, May – 2025, Page No. : 49 - 57 Corresponding Author: Dr.Sanjeev Kunhappan, ijdsir, Volume – 8 Issue - 3, Page No. : 49 - 57 Page49 ISSN: 2581-5989 PubMed - National Library of Medicine - ID: 101738774 Comparative Evaluation of Peroxide Release during Non-Vital Bleaching Using RMGIC, MTA and Biodentine as Intracoronal Barriers: An in Vitro Study 1Dr. Sial Shruti, MDS, Reader, Department of Conservative Dentistry and Endodontics, Govt. Dental College, Raipur, Chhattisgarh, Pin: 492001 2Dr. K K Saraf, MDS, Reader, Department of Conservative Dentistry and Endodontics, Govt. Dental College, Raipur, Chhattisgarh, Pin: 492001 3Dr. Shandilya Ashutosh, MDS, Lecturer, Department of Conservative Dentistry and Endodontics, Govt. Dental College, Raipur, Chhattisgarh, Pin: 492001 4Dr. Agrawal Muskan, Post Graduate Student, Department of Conservative Dentistry and Endodontics, Govt. Dental College, Raipur, Chhattisgarh, Pin: 492001 5Dr. Sandhiya Rajendran, Post Graduate Student, Department of Conservative Dentistry and Endodontics, Govt. Dental College, Raipur, Chhattisgarh, Pin: 492001 6Dr. Lija Tharakan James, Post Graduate Student, Department of Conservative Dentistry and Endodontics, Govt. Dental College, Raipur, Chhattisgarh, Pin: 492001 7Dr.Sanjeev Kunhappan, MDS, Professor, Department of Conservative Dentistry and Endodontics, Govt. Dental College, Raipur, Chhattisgarh, Pin: 492001 Corresponding Author: Dr.Sanjeev Kunhappan, MDS, Professor, Department of Conservative Dentistry and Endodontics, Govt. Dental College, Raipur, Chhattisgarh, Pin: 492001 Citation of this Article: Dr. Sial Shruti, Dr. K K Saraf, Dr. Shandilya Ashutosh, Dr. Agrawal Muskan, Dr. Sandhiya Rajendran, Dr. Lija Tharakan James, Dr.Sanjeev Kunhappan, “Comparative Evaluation of Peroxide Release during NonVital Bleaching Using RMGIC, MTA and Biodentine as Intracoronal Barriers: An in Vitro Study”, IJDSIRMay – 2025, Volume – 8, Issue – 3, P. No. 49 – 57. Copyright: © 2025, Dr.Sanjeev Kunhappan, et al. This is an open access journal and article distributed under the terms of the creative common’s attribution non-commercial License. Which allows others to remix, tweak, and build upon the work non-commercially, as long as appropriate credit is given, and the new creations are licensed under the identical terms. Type of Publication: Original Research Article Conflicts of Interest: Nil Abstract Background: Bleaching agents may lead to external cervical root resorption if peroxide leaks into periodontal space. To shield surrounding tissues and inhibit such leaking, an intra-coronal barrier is placed beneath bleaching agents. Aim: To evaluate and compare peroxide release during non-vital bleaching on Day 1 and 3 using ResinModified Glass Ionomer Cement (RMGIC), Mineral Dr.Sanjeev Kunhappan, et al. International Journal of Dental Science and Innovative Research (IJDSIR) ©2025 IJDSIR, All Rights Reserved Page50 Page50 Page50 Page50 Page50 Page50 Page50 Page50 Page50 Page50 Page50 Page50 Page50 Page50 Page50 Page50 Page50 Page50 Page50 Trioxide Aggregate (MTA) and Biodentine as intracoronal barriers. Materials and Methods: Fifty-one maxillary central incisors were collected and root canal treatment was done. 3-millimeter section of gutta-percha from coronal end were removed and samples were allocated into three groups (n=17): Group A (RMGIC), Group B (MTA) and Group C (Biodentine). Intra-coronal barrier was placed beneath the orifice. Non-vital bleaching was carried out with 35% Hydrogen Peroxide gel and peroxide release was measured on Day 1 and 3 using UV spectrophotometer. Paired t-test and One-way ANOVA followed by Tukey’s Post Hoc test was used for statistical analysis. Results: Biodentine and MTA showed significant difference out performing RMGIC on both days. No significant difference was observed between Biodentine and MTA. Conclusion: Biodentine and MTA are effective intracoronal barriers for nonvital bleaching, showing significant improvements over time and superior performance compared to RMGIC. Biodentine and MTA demonstrated comparable efficacy. Keywords: Biodentine; Mineral Trioxide Aggregate; Non-vital Bleaching; Peroxide Release; UV spectrophotometer. Introduction Tooth colour results from a combination of optical properties and the interaction of light. Both internal and external variables are the main determinants of it. Extrinsic colour is influenced by surface deposits on the enamel, while intrinsic colour is determined by the optical characteristics of the enamel and dentin and how they interact with light.[1] There are differences in tooth discoloration's origin, appearance, location, intensity, and degree of adhesion to the tooth structure. It can be classified as intrinsic, extrinsic, or a combination of the two depending on its cause and location. [2] Non-vital tooth discoloration, caused by factors like trauma, pulp remnants, restorative or endodontic materials, is a common aesthetic concern, especially in anterior teeth. When it comes to enhance the appearance of discolored endodontically treated teeth, intra-coronal bleaching is a safer, more effective and more conservative option than crowns, veneers or composite restorations.[3] Sodium perborate combined with 30% H₂O₂, 30% hydrogen peroxide (H₂O₂) and sodium perborate combined with distilled water are among the bleaching agents that are employed.[4] External cervical root resorption is the most frequent side effect of non-vital bleaching. This happens when extremely concentrated oxidizing agents permeate into the pericemental region. The bleaching agents' acidic pH causes cementum breakdown, inflammation, and osteoclast buildup. An intra-coronal cervical barrier is advised to reduce this risk by inhibiting peroxide from penetrating into the region of the periodontal ligament. [5,6] To prevent peroxide leakage during non-vital bleaching, a number of materials have been suggested as protective barriers. These consists of Mineral Trioxide Aggregate, Cavit™, IRM®, Amalgam, Super-EBA™, Composite Resin, Calcium Enriched Mixture Cement, Glass Ionomer Cement (GIC), Resin-Modified Glass Ionomer Cement and Biodentine™.[6,7] Resin-modified formulations were developed towards the end of 1980's as a result of the incorporation of polymerizable hydrophilic resins into conventional glass ionomer cements. Free radical polymerization along with an acid-base reaction are the two mechanisms by which these materials set. Compared to conventional Dr.Sanjeev Kunhappan, et al. International Journal of Dental Science and Innovative Research (IJDSIR) ©2025 IJDSIR, All Rights Reserved Page51 Page51 Page51 Page51 Page51 Page51 Page51 Page51 Page51 Page51 Page51 Page51 Page51 Page51 Page51 Page51 Page51 Page51 Page51 glass ionomers, resin-modified glass ionomer cements demonstrated improved mechanical properties such as prolonged working time, improved translucency and faster setting. Due to their high flexural strength, dentinlike elastic modulus, chemical bond with tooth structure, along with resistance to bleaching agent-induced disintegration, they are employed as coronal barrier materials. [8,9] In endodontics, calcium silicate-based cements have gained popularity recently due to their superior marginal flexibility, sealing ability and biocompatibility with the oral environment.[10] Furthermore, they are advised for a number of procedures, including coronal barrier materials, root-end fillings, vital pulp therapy, regenerative endodontic treatments, perforation repairs, and apexification. [11] MTA's high calcium hydroxide concentration, superior marginal adaptation, and resistance to microleakage make it an effective intra-coronal barrier that prevents root resorption in the cervical area. High initial solubility, a longer setting time, handling challenges, and tooth discoloration are some of its drawbacks. [12,13] Biodentine™, a calcium silicate-based cement introduced in 2009, is specifically developed as a ‘dentin replacement’ material. [4] Because of its non-toxicity, short setting time, ease of handling, dentin remineralizing qualities, and similar mechanical characteristics to dentin, biodentine is utilized as an intra-coronal barrier material. Biodentine's clinical characteristics and indications are comparable to those of MTA cement, but it has better physical qualities and is easier to handle.[3,14] This article aims to assess the amount of peroxide leakage using RMGIC, MTA and Biodentine as intracoronal cervical barriers during non-vital bleaching. Materials and Methods After informing the patients about the study and taking consent from them, fifty-one freshly extracted maxillary central incisors were used as sample in the study. The teeth were stored in distilled water with a 0.1% thymol solution after being cleaned with an ultrasonic scaler. The study excluded teeth that had undergone endodontic treatment, had cracks, fractures or root caries or had cervical abrasions. A No. 2 round bur (Mani, India) was used to prepare the access cavities in each tooth (Figure 1-a, 1b).Determination of working length was done with #10 K-file (Mani, India) and adjusted by subtracting 0.5 mm. Wal-flex anterior rotary files (Waldent Innovations India Pvt. Ltd., India) were used for shaping and cleaning up to size 60/2%. For irrigation, 3% sodium hypochlorite and 17% EDTA were used for one minute, followed by saline. The canals were coated with AH Plus sealant (Dentsply, De Trey GmBH, Konstanz, Germany) after being dried with paper points. The cold lateral compaction technique was used to obturate the canal with gutta-percha (Dentsply, Maillefer, Switzerland) (Figure 1-c).The teeth were incubated at 37°C for seven days after access cavities were filled with temporary filling material (Cavit G, 3M Deutschland GmbH, Germany). Using the labial cement-enamel junction (CEJ) as the reference point, 3 mm of gutta-percha was removed after 7 days using heated pluggers (Figure 1-d, 1-e). Based on the intra-coronal barrier, the samples were divided into three groups: Group AFuji II LC (GC Corporation, Tokyo, Japan); Group B - MTA (Angelus, Londrina, Brazil); Group C - Biodentine® (Septodont, Saint-Maurdes-Fosses, France) with 17 samples in each group. The manufacturer's recommendations were followed while creating intra-coronal barriers (Figure 2-a, 2-b, 2-c).The Dr.Sanjeev Kunhappan, et al. International Journal of Dental Science and Innovative Research (IJDSIR) ©2025 IJDSIR, All Rights Reserved Page52 Page52 Page52 Page52 Page52 Page52 Page52 Page52 Page52 Page52 Page52 Page52 Page52 Page52 Page52 Page52 Page52 Page52 Page52 barrier in the MTA group was covered with cotton soaked in saline and the cavity was filled for a whole day using temporary restorative material. Radiographs were taken to verify the barrier placement (Figure 1-f) and all surfaces except cervical 3 mm below the CEJ were painted with nail polish (Figure 2-e). Following a 24-hour period, access cavities were opened again and in accordance with the manufacturer's directions, non-vital bleaching was carried out using Opalescence Endo (Ultradent, South Jordan, UT, USA) (Figure 2-d).Glass ionomer cement (GC Corporation, Tokyo, Japan) was used to reseal the cavities. Samples were then immersed in Eppendorf tubes filled with two millilitres of distilled water and incubated for three days at 37°C. (Fig. 2-f). On the first and third days, the samples' peroxide release in distilled water was evaluated using UV spectrophotometry and potassium iodide (KI) solution. The absorbance of 2 mL of the sample solution was measured at 390 nm using a UV-1900i Double Beam UV-VIS Spectrophotometer (Shimadzu, Japan) after adding 200 microliters of KI solution. The absorbance of the samples on the first and third days was compared in order to determine the peroxide concentration in the samples. Statistical Analysis The data was statistically analyzed using the Paired t-test for intra-group comparison and the one-way ANOVA followed by Tukey's Post Hoc test for intergroup comparison. The mean and standard deviation were calculated for each group. SPSS 11.5 software for Windows (SPSS Inc., Chicago, IL, USA) was used to conduct analyses at the 5% significance level, and a Pvalue of less than 0.05 was considered statistically significant. Results The research assessed the relative effectiveness of different intra-coronal barriers - RMGIC, MTA and Biodentine used in non-vital bleaching technique. The intra-group analysis (Table no. 1) showed that both MTA and Biodentine exhibited significant changes from 1stto 3rdDay (P=0.005andP=0.004, respectively), while no statistically significant difference (P=0.057) was shown by RMGIC group. The lowest peroxide release was observed in the Biodentine group, followed by MTA and then RMGIC on both days. The inter-group comparison (Table no. 2) revealed significant differences between the materials, with Biodentine and MTA showing significantly better performance than RMGIC on both days. Nevertheless, no significant difference was observed between MTA and Biodentine on either day. Discussion The main problem with nonvital bleaching is the resorption of external cervical roots surface. This occurs as a consequence of the bleaching agent's peroxide leaking from the tooth into the periodontal space, which damages the cementum and causes inflammation. [4] One of the main causes of cervical root resorption is the drop in pH on the tooth's surface that occurs after intracoronal whitening. The dentinal tubules, which join the pulp to the root surface, should be sealed with a filler material to avoid this. However, because neither the filling material nor the sealer can completely prevent chemicals from escaping into the canal, a filled root canal is still susceptible to microleakage. [10] The bleaching agent utilized in this study was 35% H2O2 gel and the maximum amount of peroxide released 24 hours after bleaching and gradually diminished over time, aligning with the result of study done by Roy et al. and Zoya et al. [4,15] Dr.Sanjeev Kunhappan, et al. International Journal of Dental Science and Innovative Research (IJDSIR) ©2025 IJDSIR, All Rights Reserved Page53 Page53 Page53 Page53 Page53 Page53 Page53 Page53 Page53 Page53 Page53 Page53 Page53 Page53 Page53 Page53 Page53 Page53 Page53 In a bacterial leakage study, Khanna et al found that the seal of RMGIC as orifice barrier was inferior compared to MTA. [16]In the current study, the RMGIC group released the greatest amount of peroxide on the first day. This might have occurred because of microleakage through RMGIC that can be possibly because of shrinkage during polymerization, poor condensation or improper manipulation that produced a non-homogenous mix.[10,17] According to Torabinejad et al[18]., MTA has greater marginal adaptability, which contributes to its leakage resistance. This sealing ability is ascribed to its hydrophilic properties and its expansion when set in a damp condition. Additionally, MTA results in lesser porosity because it is a condensable material. The development of hydroxyapatite crystals at the material-dentine interface may be the cause of the lower peroxide release in the biodentine and MTA groups. [3,19] In the current study, the likely reasons for Biodentine outperforming MTA could be:  Biodentine forms tag-like structures and an interfacial layer known as the "mineral infiltration zone" on coming in contact with dentin. The collagen components of the interfacial dentin are broken down by the alkaline-caustic action of the calcium silicate cement's hydration products, which improves Biodentine's capacity to seal by encouraging the production of these tags. [20]  Biodentine's smaller particle size enables it to conform well to the cavity surface, providing a robust seal at the interface. [21]  One of the benefits of Biodentine is its rapid setting time (12 minutes), which enables earlier sealing of the interface and consequently lowers the risk of leakage. [22]  Set Biodentine exhibits lower porosity and pore volume compared to MTA. [23]  Also, Biodentine is mixed in amalgamator which results in better consistency of mix compared to MTA which is mixed manually. Its prolonged setting time may potentially be the cause of the relatively large leakage of MTA seen during the first 24 hours, which is consistent with the findings of Nabeel et al. [24] In comparison to the first day, peroxide emission had dramatically dropped by the third day in both the MTA and Biodentine groups. However, it was also shown that there was no statistically significant difference between the Biodentine and MTA groups on intergroup comparison, suggesting that these two materials were equally effective. This could be because MTA's structural integrity increased over time. Furthermore, the release of calcium hydroxide and the increased alkalinity of MTA help shield the root surface from resorption. The in vitro approach and the small sample size of this investigation restricted the evaluation of clinically significant parameters. Peroxide release from bleaching chemicals requires further study in a setting that is more clinically relevant. Conclusion Within the confines of the investigation, MTA and Biodentine both demonstrated a considerable decrease in peroxide release over time. RMGIC, however, did not exhibit any statistically significant alteration. Inter-group comparisons also showed that Biodentine and MTA performed noticeably better than RMGIC. Nonetheless, MTA and Biodentine showed equivalent results, with no discernible difference, suggesting that these two materials are equally effective. The results of this study indicate that MTA and Biodentine are better intracoronal barriers than RMGIC, which makes them better options for clinical application in the nonvital bleaching process. Dr.Sanjeev Kunhappan, et al. International Journal of Dental Science and Innovative Research (IJDSIR) ©2025 IJDSIR, All Rights Reserved Page54 Page54 Page54 Page54 Page54 Page54 Page54 Page54 Page54 Page54 Page54 Page54 Page54 Page54 Page54 Page54 Page54 Page54 Page54 References 1. Plotino G, Buono L, Grande NM, Pameijer CH, Somma F. Nonvital tooth bleaching: a review of the literature and clinical procedures. J Endod 2008;34:394-407. 2. Dahl JE, Pallesen U. Tooth bleaching-a critical review of the biological aspects. Crit Rev Oral Biol Med 2003;14:292–304. 3. Sakalli B, Basmaci F, Dalmizrak O. Evaluation of the penetration of intra-coronal bleaching agents into the cervical region using different intraorifice barriers. BMC Oral Health 2022;22:266. 4. Roy D, Kataki R, Gogoi S, Seal M. Evaluation of peroxide release during nonvital bleaching using three different coronal barriers: An in vitro study. J Conserv Dent Endod 2024;27:920-4. 5. Fernandes M, Menezes L, De Ataide I. Management of invasive cervical resorption using a surgical approach followed by an internal approach after 2 months due to pulpal involvement. J Conserv Dent 2017;20:214-8. 6. Rotstein I, Zyskind D, Lewinstein I, Bamberger N. Effect of different protective base materials on hydrogen peroxide leakage during intra-coronal bleaching in vitro. J Endod 1992;18:114-7 7. Vosoughhosseini S, Lotfi M, Shahmoradi K, Saghiri MA, Zand V, Mehdipour M et al. Microleakage comparison of glass-ionomer and white mineral trioxide aggregate used as a coronal barrier in nonvital bleaching. Med Oral Patol Oral Cir Bucal 2011;16:e1017-21. 8. Bhattacharya A, Vaidya S, Tomer AK, Raina A. GIC at its best – A review on ceramic reinforced GIC. Int J Appl Dent Sci 2017;3:405-8. 9. Feiz A, Faghihian H, Mahdaviani MS. Effect of different protective bases on pH changes and hydrogen peroxide microleakage during intracoronal bleaching. Front Dent 2023:20:14. 10. McCabe P. Revascularization of an immature tooth with apical periodontitis using a single visit protocol: a case report. Int Endod J 2015;48:484–97. 11. Abraham S, Chandwani ED, Nagmode P, Lokhande N, Badgujar MB, Diggikar K. A spectrophotometric comparative evaluation of the sealing ability of various perforation repair materials with a novel eggshell modified GIC. J Conserv Dent Endod 2023;26:697-701. 12. Choi YL, Jang YE, Kim BS, Kim JW, Kim Y. Preapplication of dentin bonding agent prevents discoloration caused by mineral trioxide aggregate. BMC Oral Health 2020;20:163. 13. Torabinejad M, Parirokh M, Dummer PMH. Mineral trioxide aggregate and other bioactive endodontic cements: an updated overview - part II: other clinical applications and complications. Int Endod J 2018;51:284–317. 14. Solanki NP, Venkappa KK, Shah NC. Biocompatibility and sealing ability of mineral trioxide aggregate and biodentine as root-end filling material: A systematic review. J Conserv Dent 2018;21:10-5. 15. Zoya A, Tewari RK, Mishra SK, Faisal SM, Ali S, Kumar A, et al. Sodium percarbonate as a novel intra-coronal bleaching agent: Assessment of the associated risk of cervical root resorption. Int Endod J 2019;52:701-8. 16. Khanna SK, Rao HM, Aga N, Chandra P. Comparing bacterial leakage of three intraorifice barrier sealing materials against Enterococcus faecalis and Proteus vulgaris. J Contemp Dent Pract 2021;22:674–679. Dr.Sanjeev Kunhappan, et al. International Journal of Dental Science and Innovative Research (IJDSIR) ©2025 IJDSIR, All Rights Reserved Page55 Page55 Page55 Page55 Page55 Page55 Page55 Page55 Page55 Page55 Page55 Page55 Page55 Page55 Page55 Page55 Page55 Page55 Page55 17. Malik G, Bogra P, Singh S, Samra RK. Comparative evaluation of intracanal sealing ability of mineral trioxide aggregate and glass ionomer cement: An in vitro study. J Conserv Dent 2013;16:540-5. 18. Torabinejad M, Smith PW, Kettering JD, Pitt Ford TR. Comparative investigation of marginal adaptation of mineral trioxide aggregate and other commonly used root end filling materials. J Endod 1995;21:295-9. 19. Torabinejad M, Chivian N. Clinical applications of mineral trioxide aggregate. J Endod 1999;25:197205. 20. Atmeh AR, Chong EZ, Richard G, Festy F, Watson TF. Dentin-cement interfacial interaction: calcium silicates and polyalkenoates. J Dent Res. 2012;91:454-9. 21. Koubi G, Colon P, Franquin JC, Hartmann A, Richard G, Faure MO, Lambert G. Clinical evaluation of the performance and safety of a new dentine substitute, Biodentine, in the restoration of posterior teeth - a prospective study. Clin Oral Investig 2013;17:243-9. 22. Kaup M, Schäfer E, Dammaschke T. An in vitro study of different material properties of Biodentine compared to ProRoot MTA. Head Face Med 2015;11:16. 23. Camilleri J, Sorrentino F, Damidot D. Investigation of the hydration and bioactivity of radiopacified tricalcium silicate cement, Biodentine and MTA Angelus. Dent Mater. 2013;29:580-93. 24. Nabeel M, Tawfik HM, Abu-Seida AM, Elgendy AA. Sealing ability of Biodentine versus proroot mineral trioxide aggregate as root-end filling materials. Saudi Dent J 2019;31:16-22. Legend Tables and Figures: Table 1: Mean peroxide release (Intra-group comparison) Paired Samples Statistics Mean concentration (%) N Std. Deviation Mean Difference P value Rmgic (Group A) 1st Day 0.2194 17 0.04790 0.056 0.057 3rd Day 0.1628 17 0.03435 MTA (Group B) 1st Day 0.1726 17 0.03729 0.059 0.005 3rd Day 0.1128 17 0.03195 Biodentine (Group C) 1st Day 0.1536 17 0.02550 0.055 0.004 3rd Day 0.0978 17 0.01800 Table 2: Multiple Group Comparison (Inter-group comparison) (TUKEY HSD) Dependent Variable (I) Group (J) Group Mean Difference (I-J) Std. Error Sig. 95% Confidence Interval Lower Bound Upper Bound DAY 1 Rmgic MTA 0.0468 0.0203 0.081 0.0050 0.0987 Biodentine 0.0657* 0.0203 0.012 0.0139 0.1176 MTA Rmgic -0.0468 0.0203 0.081 -0.0987 0.0050 Dr.Sanjeev Kunhappan, et al. International Journal of Dental Science and Innovative Research (IJDSIR) ©2025 IJDSIR, All Rights Reserved Page56 Page56 Page56 Page56 Page56 Page56 Page56 Page56 Page56 Page56 Page56 Page56 Page56 Page56 Page56 Page56 Page56 Page56 Page56 Biodentine 0.0189 0.0203 0.627 -0.0329 0.0708 Biodentine Rmgic -0.0657* 0.0203 0.012 -0.1176 -0.0139 MTA -0.0189 0.0203 0.627 -0.0708 0.0329 DAY 3 Rmgic MTA 0.0499* 0.0155 0.013 0.0103 0.0895 Biodentine 0.0649* 0.0155 0.002 0.0254 0.1045 MTA Rmgic -0.0499* 0.0155 0.013 -0.0895 -0.0103 Biodentine 0.0150 0.0155 0.605 -0.0245 0.0546 Biodentine Rmgic -0.0649* 0.0155 0.002 -0.1045 -0.0254 MTA -0.0150 0.0155 0.605 -0.0546 0.0245 Figure 1: Preparation of samples Figure 1a: Access cavity preparation Figure 1b: Access cavity Figure 1c: Obturation Figure 1d: GP removal 3 mm below CEJ Figure 1e: Radiograph showing 3 mm gp removed Figure 1f: Intra-coronal barrier Figure 2:Intra-coronal barrier and peroxide release Figure 2a: Mixing of RMGIC Dr.Sanjeev Kunhappan, et al. International Journal of Dental Science and Innovative Research (IJDSIR) ©2025 IJDSIR, All Rights Reserved Page57 Page57 Page57 Page57 Page57 Page57 Page57 Page57 Page57 Page57 Page57 Page57 Page57 Page57 Page57 Page57 Page57 Page57 Page57 Figure 2b: Mixing of MTA Figure 2c: Placement of intra-coronal barrier Figure 2d: Bleaching agent placement\ Figure 2e: Coating with nail varnish Figure 2f: Samples in incubator