Evaluation of Sealing Ability of Three Root Canal Sealers: An In Vitro Study

INTRODUCTION

For ideal root canal treatment, several factors are responsible such as proper instrumentation, biomechanical preparation, obturation as well as postendodontic restoration. Thus, the main purpose of RCT is to put an end to microbial existence and to prevent reinfection of root canal. This will bring out proper sealing along with successful obturation, which acts synergistically to create hermetic seal.¹

Improper filling of canal can result in fluid movement into the defects, which may cause inflammatory reactions compromising the success of treatment.² Also the root canal ramifications, such as lateral, secondary, and accessory canals, connect root canal with the periodontal ligament and apical foramen.³

Root canal sealers are used in combination with gutta-percha for filling of root canals. Sealers obliterate the discrepancies like grooves and lateral depressions that cannot be filled with gutta-percha. Gutta-percha is impermeable; thus, leakage occurs at the sealer to gutta-percha and sealer to tooth interface.⁴

Root canal sealers have the following main functions:

• Sealing off voids, patent accessory canals, and multiple foramina.
• Forming a bond between the core of filling material and root canal wall, and
• Acting as lubricant, making the placement of filling core easier and enshrining the remaining microorganism.⁵

The capability of root canal sealers to seal root canal is reinforced by minimizing the amount of sealer and assessing good adaptation and penetration of the sealer into the root dentin.

Thickness of sealer and its adaptation to root dentin is the main function of sealer’s physical and chemical properties.⁶

Flow is an important property that shows its capability to penetrate into small irregularities and ramifications of the root canal and also the dentinal tubules. Along with flow, the antimicrobial effectiveness of root canal sealers aids in disinfection of root canal system.³

Some of the main factors for choice of sealer are:

• Its ability to form sound seal
• Well tolerated by periradicular tissue
• Easy to manipulate⁷

Different types of root canal sealers are available, with each one having their own merits and demerits. However, they are selected according to their sealing ability, adhesive properties, biocompatibility, and antimicrobial efficacy. Some of them are:

• ZnO based
• Epoxy resin based
• Glass ionomer based
• Calcium hydroxide based
• Bioceramic based
• MTA based^2,7

According to Meryon, zinc oxide eugenol-based sealers are cytotoxic, which may be due to the toxic effect of zinc ions. Eugenol is not only toxic but also neurotoxic. Thus, exclusion of eugenol helps in reducing toxicity.⁸

The main advantage of epoxy resin-based sealers is their reduced solubility and better apical seal. Calcium hydroxide-based sealers stimulate periapical tissues to facilitate healing and also for its antimicrobial effects. However, in terms of microleakage, calcium hydroxide-based sealers are not superior to other groups of sealers. Glass ionomer-based sealers are technically less demanding than traditional methods, has an inherent potential for providing a more stable apical seal, and also may prevent root fracture due to their bonding properties. The MTA-based sealers are new endodontic materials, which are based on physiochemical properties of MTA. They develop a biocompatible sealer with ideal physical, chemical, or mechanical properties, which are due to their alkaline pH, and calcium ion releasing ability.⁷ These sealers are biocompatible, stimulate mineralization, and also boost apatite-like crystalline deposits along the apical and middle third of the enamel wall. These sealers have sealing abilities similar to the epoxy-resin-based sealer.⁴

There has been regular research for alternative sealer that bonds to dentin along with the filling materials. More long-term data are needed to figure out whether the recently developed sealer used in the place of the conventional sealers will be used in parallel as an alternative choice when filling the root canal.⁷ The main aim and objective was to compare and evaluate the sealing ability of the three different types of sealers using confocal laser microscopy.

MATERIALS AND METHODS

The following materials were used in the study:

• Freshly extracted single-root premolars
• 0.2% thymol: disinfectant
• NaOCl: for irrigation between each file change
• EDTA: final irrigation
• Distilled water: to clean fractured fragment
• Sealers: MTA-Fillapex, AH Plus, and Bio C Sealer
• Rhodamine B dye: for labeling sealers

STATISTICAL ANALYSIS

The data collected was subjected to statistical analysis. Analysis of variance was used to analyze the sealing ability of the different types of sealers. Significant value was set at 0.05. Tukey test (post hoc test) was used to compare between the groups (divided according to the type of sealer used).

RESULTS

The standard deviation of MTA-Fillapex, Bio C Sealer, and AH Plus are 42.5, 47, and 73.3, respectively. AH Plus and Bio C Sealers showed significant result, while MTA Fillapex showed nonsignificant result (p > 0.001; Table 1). When comparison was done between the groups, significant correlation was seen between AH Plus (A) vs Bio C Sealer (C) and MTA-Fillapex (B) vs Bio C Sealer (C) and nonsignificant between AH Plus (A) vs MTA-Fillapex (B) (Figs 1 to 3 and Table 2). Statistically significant differences were obtained in the sealing ability of the three groups (p < 0.001). However, while comparing the sealing ability of different groups (intergroup comparison), the comparison between groups A and B was nonsignificant (p = 0.946), while the comparison between groups A and C and groups B and C was highly significant (p < 0.001).

DISCUSSION

The goal of our study was to compare the sealability of all the three sealers. All procedures were performed by the same operator to avoid intraoperator discrepancies. Only teeth with straight root canals were used because they can offer a more standardized method for evaluation of apical leakage. However, using a single-cone technique for root canal filling allowed observing the sealability of the sealers in more critical situation than that offered by the lateral condensation technique as it is possible to speculate that the single-master cone needs a greater interaction with the sealer to promote the sealing.^9,10 Rhodamine B dye was used because it does not suffer discoloration by calcium hydroxide-based materials as seen with methylene blue.¹¹

We choose the AH Plus sealer because it is used frequently in clinical work and is usually chosen as the control in studies on the properties of new sealers because of its good flowability, proper film thickness, and viscosity. The most critical area of the prepared root canal is the 2–3 mm of apical third, hence we choose it.

The AH Plus is an epoxy-resin-based sealer. It is used because of its reduced solubility, better apical seal, microretention to root canal dentin, and less shrinkage.^7,12

The MTA Fillapex is a bioceramic and resin sealer. It is biocompatible and encourages apatite-like crystalline deposits along the apical and middle third of the canal walls.^4,13

The Bio C is a novel bioceramic, nonresin sealer, which stimulates tissue regeneration.¹⁴

The flow, setting time, and solubility of all three sealers are shown in Table 3.

The present study showed high dye penetration with respect to AH Plus followed by MTA Fillapex and then Bio C Sealer.

Many researchers concluded that AH Plus shows more dye penetration. Gandolfi et al. found that AH Plus demonstrated better sealing ability than that of MTA.¹⁵ Almeida et al. concluded that AH Plus permitted less dye leakage than pulp canal sealer.³ Al Haddad et al. found that AH Plus exhibits the least number of gap-containing regions than MTA Fillapex.⁶ Tyagi et al. found better penetration of it into the microirregularities.¹ Viapiana found that AH Plus exhibits higher percentage of root canal filling than Bio C Sealer.¹⁶

Superior adaptation of AH Plus is due to its ability to bond to root dentin chemically by reacting with the exposed amino groups in collagen to form covalent bonds between the epoxy resin and collagen. The AH Plus sealer is slightly acidic and might result in self-etching when in contact with dentin, unlike the alkaline bioceramic-based sealers, thereby enhancing interfacial bonding and adaptation.^3,6,17

According to Hubbe et al., AH Plus is a thixotropic fluid that undergoes transformation of its internal structure, which promotes the alternation of the flow speed accounting for the abrupt flow after a certain time.¹⁸ Al-Haddad et al. stated that hydrophobicity of this sealer facilitates the permeation of resin into open dentinal tubules and creates efficient microretention when 17% EDTA was used as the final irrigant.⁶

Many researchers found that AH Plus shows less dye penetration. Candeiro et al.¹⁷ proved that AH Plus has lower flow rate compared to the Endosequence BC sealer. Ormiga et al. concluded that Endorez sealer filled a greater number of ramification compared to AH Plus. Sydney et al. stated that endofill exhibits the highest flow compared to AH Plus. The BC sealer and MTA Fillapex demonstrated better tubule penetration than AH Plus sealer.^5,19,20

Gomes et al., Zhou, and Weller et al. found that MTA-based sealers show more dye penetration as it showed superior sealing ability, lower leakage of dye, and greater flow values compared to AH Plus.^2,21,22 Joe D’souza et al. concluded that before selecting a sealer, it is necessary to find a sealer that can seal the canal properly, inhibit bacterial growth as well as tolerated by periradicular tissue.⁸ Yigit et al. found that AH Plus is the most soluble sealer. According to them, all root canal sealers have acceptable properties except for dimensional stability.²³

Singh et al. discussed the current concepts in the usage of different endodontic sealers and concluded that apical seal of root canal and the coronal seal are important for the success of root canal treatment.²⁴

CONCLUSION

Root canal sealers, although used only as adjunctive materials in the obturation of root canals, have been shown to influence the outcome of endodontic treatment.

An ideal root canal sealer should possess perfect combination of sealing ability and biocompatibility.

Significant difference was found between the sealing ability of AH Plus, MTA Fillapex, and Bio C Sealers.

Understanding of the current concepts in the usage of different sealers in endodontic therapy and their comparison is essential in order to draw some clinical inferences.

Further investigations are needed for Bio C Sealer.

REFERENCES

1. Tyagi S, Mishra P, Tyagi P. Evolution of root canal sealers: an insight story. Eur J Gen Dent 2013;2(3):199–218. DOI: 10.4103/2278-9626.115976.

2. Gomes-Filho JE, Moreira JV, Watanabe S, et al. Sealability of MTA and calcium hydroxide containing sealers. J Appl Oral Sci 2012;20(3):347–351. DOI: 10.1590/S1678-77572012000300009.

3. Almeida JF, Gomes BP, Ferraz CC, et al. Filling of artificial lateral canals and microleakage and flow of endodontic sealers. Int Endod J 2007;40(9):692–699. DOI: 10.1111/j.1365-2591.2007.01268.x.

4. Camilleri J, Gandolfi MG, Siboni F, et al. Dynamic sealing ability of MTA root canal sealer. Int Endod J 2011;44(1):9–21. DOI: 10.1111/j.1365-2591.2010.01774.x.

5. Al-Haddad A, Che Ab Aziz ZA. Bioceramic-based root canal sealers: A review. Int J Bio 2016; 1–10. DOI: 10.1155/2016/9753210.

6. Al-Haddad A, Abu Kasim NH, Che Ab Aziz ZA. Interfacial adaptation and thickness of bioceramic-based root canal sealers. Dent Mater J 2015;34(4):516–521. DOI: 10.4012/dmj.2015-049.

7. Khandelwal D, Ballal NV. Recent advances in root canal sealers. Int J Clin Dent 2016;9(3):183–194.

8. Henston JL, Sharma N, Subhash C, et al. Root canal sealers and its role in successful endodontics: a review. ADR 2012;2(2):68–78.

9. Wu MK, van der Sluis LW, Ardila CN, et al. Fluid movement along the coronal two thirds of root fillings placed by three different guttapercha techniques. Int Endod J 2003;35:54–63.

10. Gomes-Filho JE, Bernabé PF, Nery MJ, et al. Reaction of rat connective tissue to a new calcium hydroxide based sealer. Oral Surg Oral Med Oral Pathol Oral Radiol Endod 2008;106(2):71–76. DOI: 10.1016/j.tripleo.2008.03.030.

11. Venturi M, Prati C, Capelli G, et al. A preliminary analysis of the morphology of lateral canals after root canal filling using a tooth clearing technique. Int Endod J 2003;36(1):54–63. DOI: 10.1046/j.0143-2885.2003.00613.x.

12. Marín-Bauza GA, Silva-Sousa YT, da Cunha SA, et al. Physiochemical properties of endodontic sealers of different bases. J Appl Oral Sci 2012;20(4):455–461. DOI: 10.1590/S1678-77572012000400011.

13. Rawtiya M, Verma K, Singh S, et al. MTA based root canal sealers. J OrafacRes 2013;3(1):16–21. DOI: 10.5005/jp-journals-10026-1057.

14. Angelus. MTA Fillapex bio ceramic endodontic sealer. Scientific Technical Profile 2018; 8–18.

15. Gandolfi MG, Prati C. MTA and F-doped MTA cements used as sealers with warm gutta-percha long-term study of sealing ability. Int Endod J 2010;43(10):889–901. DOI: 10.1111/j.1365-2591.2010.01763.x.

16. Viapiana R, Flumignan DL, Guerreiro TJM, et al. Physicochemical and mechanical properties of zirconium oxide and niobium oxide modified Portland cement-based experimental endodontic sealers. Int Endod J 2014;47(5):437–448. DOI: 10.1111/iej.12167.

17. Candeiro GT, Correia FC, Duarte MA, et al. Evaluation of radiopacity, pH, release of calcium ions, and flow of a bioceramic root canal sealer. J Endod 2012;38(6):842–845. DOI: 10.1016/j.joen.2012.02.029.

18. Hubbe KL, de Oliveria KVD, Coelho BS, et al. AH plus extrusion into apical tissue: literature review of main related properties and report of clinical cases. RSBO 2016;13(4):280–288. DOI: 10.21726/rsbo.v13i4.352.

19. Wang Z, Shen Y, Haapasalo M. Dentin extends the antibacterial effect of endodontic sealers against enterococcus faecalis biofilms. J Endod 40(4):505–508. DOI: 10.1016/j.joen.2013.10.042.

20. El Hachem R, Khalil I, Le Brun G, et al. Dentinal tubules penetration of AH plus, BC sealer and novel tricalcium silicate sealer: A confocal laser scanning microscopy study. Clin Oral Inv 2019;23(4):1871–1876. DOI: 10.1007/s00784-018-2632-6.

21. Zhou HM, Shen Y, Zheng W, et al. Physical properties of 5 root canal sealers. J Endod 2013;39(10):1281–1286. DOI: 10.1016/j.joen.2013.06.012.

22. Weller RN, Tay KC, Garrett LV, et al. Microscopic appearance and apical seal of root canals filled with gutta-percha and ProRoot Endo sealer after immersion in a phosphate-containing fluid. Int Endod J 2008;41(11):977–986. DOI: 10.1111/j.1365-2591.2008.01462.x.

23. Yigit DH, Gencoglu N. Evaluation of resin/silicon based sealers. Part I: Physical properties. Dig J NanomaterBiostruct 2012;7(1):107–115.

24. Singh H, Markan S, Kaur M, et al. Endodontic sealers”: current concepts and comparative analysis. Dent Open J 2015;2(1):32–37. DOI: 10.17140/DOJ-2-107.