Choosing an endodontic sealer for clinical use is a decision that contributes to the long-term success of non-surgical root canal treatment (NSRCT) [1]. Sealers are used as a thin tacky paste which functions as a lubricant and luting agent during obturation, allowing the core obturation material, such as gutta-percha points or other rigid materials, to slide in and become fixed in the canal [2,3]. Sealers can fill voids [4], lateral canals [5], and accessory canals where core obturation materials cannot infiltrate [6,7]. If the sealer does not perform its function, microleakage may cause NSRCT failure via clinically undetectable passage of bacteria, fluids, molecules or ions between the tooth and restorative material [8,9]. Knowing the qualities and characteristics of an endodontic sealer is critical to determining the best selection and application for each clinical case. Endodontic sealers are categorized by composition based on setting reaction and composition: zinc oxide eugenol, salicylate, fatty acid, glass ionomer, silicone, epoxy resin, tricalcium silicate, and methacrylate resin sealer systems. Some novel sealers contain fillers or ceramic powders including calcium hydroxide, mineral trioxide aggregate (MTA), and calcium phosphate; however, they are fundamentally composed of the above sealer matrices. Until recently, many review articles were published within sealer types [10-16]. However, few reviews have been published that cover all sealer types [17,18]. Therefore, in this comprehensive review, a historical perspective of each sealer type will be discussed first, followed by a description of the properties of all sealer types, such as setting time and solubility, sealing ability, antimicrobial activity, and biocompatibility and cytotoxicity.

Functions of a Sealer

• Sealer as Cement (luting/ binding): Sealers act as binding agent for gutta percha cones in lateral condensation obturation technique and also serves to bind the gutta percha to dentinal wall

• Sealer as Filler: Sealers are used to fill the gap between the core material and wall of the root canal, between the individual cone, root canal irregularities and the inaccessible areas of the root canal

• Bioactivity: Sealers might influence the host response by actively interacting with the local tissue environment. Calcium hydroxide and MTA based sealers can be considered as bioactive sealers with bioactivity

• Sealer as an Antibacterial agent: Sealers should be able to control or restrict bacterial growth. Zinc oxide eugenol, Calcium hydroxide and Calcium silicate-based sealers have significant antibacterial properties

• Sealer as a Lubricant: When used with solid/semisolid obturation materials, sealers act as a lubricant thereby aiding in easy seating of obturation material in the apical area

• Sealers may also act as a marker for root resorption, accessory canals root fractures and other spaces into which the main core material may not penetrate, thereby making their clinical or radiographic determination easy

Classification of root canal sealers Various sealers according to their primary constituent or structure are:

Zinc Oxide Eugenol Sealers

• Rickert’s sealer / Kerr’s Pulp Canal Sealer (Kerr manufacturing Co.)

• ProcoSol (Star dental, Conshohocken, PA)         

• Roth’s 801 sealer / Grossman’s sealer / U/P Root Canal Sealer (Sultan, USA)

• TubliSeal (Sybron Endo / Kerr; Orange, Calif.)

• Wach’s Sealer / Sealex Extra (Sultan Chemists/ Balas Dental, Chicago, IL, 60602)

• Fill canal sealer 

• Intrafill (SS White, Brazil)

• Sultan

• Medicated Canal Sealer, MCS (Medidenta, Woodside, N.Y.) 

• Canals (Syowa Yakuhin, Japan) 

Non-Eugenol Zinc Oxide Sealers 

• Nogenol (G-C America, Alsip, III, Japan) 

• Canals-N (Syowa Yakuhin, Japan)

   

Calcium Hydroxide Sealers 

• CRCS/ Calciobiotic root canal sealer (Hygienic corp., USA) 

• Apexit (Ivoclar Vivadent, Schaan, Lichtenstein) 

• Sealapex (Kerr manufacturing Co.) 

• Acroseal (Septodont, France) 

• LIFE (Sybron Endo/Kerr; Orange, Calif) 

• Vitapex (NEO Dental, Japan) 

• Dentalis (NEO Dental, Japan) 

• Sealer 26 (Dentsply, Petropolis, Brazil)

Glass Ionomer Sealers

• Ketac Endo (3M ESPE, Seefeld, Germany) 

• Ketac Cem 3. Endion (VOCO, Germany)

Gutta Percha Sealers / Chloroform based Sealers 

• Chloropercha (Moyco, Union Broach, York, PA)

• Kloroperka N-Ø (N-Ø Therapeutics, Oslo, Norway)

• Rosin chloroform 

Sealers Containing Formaldehyde

• Endomethasone 

• N2/ RC-2B/ Sargenti paste (Indrag- Agsa, Bologna, Italy) 

• Riebler’s paste (Amubarut, Germany) 

• SPAD

Polymers 

Resin Based Sealers Epoxy Resin Sealers

• AH 26 / Thermaseal (De Trey, Zurich, Switzerland / Caulk, Dentsply) 

• AH Plus/ Thermaseal Plus / Topseal (Caulk, Dentsply)

Polyketone Based Sealers 

• Diaket (ESPE, Seefeld, Oberbayern, Germany)

•  Methacrylate resin- based sealers 

• EndoREZ (Ultradent, South Jordan, UT)

• Epiphany (Pentron, Wallingford, CT)

• InnoEndo (Heraeus- Kulzer, Armonk, NY)

Calcium -Silicate Based Sealers 

• iRoot-SP 

• MTA-Fillapex(Angelus) 

• ProRoot Endo sealer(Dentsply) 

• CPM sealer (Egeo-Argentira) 

• MTA-Obtura(Angelus)

• F-doped MTA

• MTAS experimental sealer

Grossman Listed 11 Requirements and Characteristics of a Good Root Canal Sealer [19]

• It should be tacky when mixed to provide good adhesion to the canal wall when set

• It should develop a hermetic seal

• It should set slowly

• It should be radiopaque so that it can be visualized in the radiograph

• The particles of powder should be very fine so that they can mix easily with the liquid

• It should not shrink upon setting. 6. It should not stain tooth structure

• It should be bacteriostatic or at least not encourage bacterial growth

• It should be insoluble in tissue fluids

• It should be tissue tolerant, that is, nonirritating to periradicular tissue

• It should be soluble in a common solvent, if necessary to remove the root canal filling

• Few other requirements that can be added to Grossman’s 11 basic requirements are

• It should not provoke an immune response in periradicular tissue

• It should be neither mutagenic nor carcinogenic

• It should be capable of bonding to dentin or guttapercha / core obturation material

The Concept of Monoblock

The term monoblock literally means a single unit. Franklin R. Tay first described the concept of monoblock in endodontics [20].

Primary Monoblock

It has only one interface that extends circumferentially between the material and the root canal wall. A classic example of primary monoblock would be obturating the root canals with gutta percha, without using the sealer. Use of Hydron sealer alone is another example of this concept. The lack of sufficient strength and stiffness is the major drawback and this led to the development of Secondary monoblocks.

Secondary Monoblock

Secondary monoblocks are the ones having two circumferential interfaces, such as one between the cement and dentin and the other between the cement and the core material. A classic example would be the use of sealer for obturation, wherein one interface is between Gutta Percha point and sealer and the the second one between the sealer and root canal wall. Interest in utilizing the monoblock concept for reinforcing the root canal space was got resurfaced in around 2004 with the advent of bondable root filling materials that were launched as alternatives to conventional gutta-pethis category, may be used for either lateral or warm vertical compaction techniques. 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.

Tertiary Monoblock

Tertiary monoblocks are the ones having an additional third circumferential interface between the bonding substrate and the abutment material. Fiber posts that contain either an external silicate coating or those that contain unpolymerized resin composite for relining root canals that are too wide or not perfectly round for the fitting of conventional fiber posts may be considered as tertiary monoblocks. Tenax Fibre post (Coltene) have a specific resin coating on its surface, which when cured with dual cure resin ParaCore (Coltene) forms a typical Teriary monoblock: with one interface between the fibre post and the resin coating; the second one between the resin coating and the luting cement; and the third one between the luting cement and the root canal wall. Another product that falls into this category is the EndoRez system (Ultradent), in which the conventional gutta-percha cones are coated with a proprietary resin coating. rcha as obturating materials

Recent Endodontic Sealers

ProRoot Endo Sealer 

It is an experimental calcium silicate-based root canal sealer that is designed to be used in conjunction with a root filling material in either the cold lateral, warm vertical or carrier-based filling techniques. The major components of the powder component are tricalcium silicate and dicalcium silicate, with the inclusion of calcium sulphate as a setting retardant, bismuth oxide as a radiopacifier and a small amount of tricalcium aluminate. The liquid component consists of a viscous aqueous solution of a water-soluble polymer. Similar to other tricalcium silicate and dicalcium silicate-containing biomaterials, the sealer produces calcium hydroxide on reaction with water [21].

Herbal Sealer (Biosealer)

 It is an experimental root canal sealer based on Copaifera multijuga oil-resin. Trees belonging to the genus Copaifera are distributed around northern South America, mainly in the Amazon Rainforest. It is one of the most popular and promising phytomedicines used in Brazil. The powder is composed of zinc oxide, calcium hydroxide, bismuth subcarbonate, natural resin (rosin) and borax, and the liquid is purified Copaifera multijuga oil-resin (Prezi.com).

Nanoseal plus root canal sealer

 A common cause of failure of root canal treatment is due to the inability to seal the accessory canal in most cases. One of the newest updates in endodontics is the development of the first endodontic sealer based on nanotechnology which actively seals the tiny gaps thereby reducing the infection. It is made up of calcium phosphate hydroxyapitite nanoparticles range from 40-60 nm. The rod-shaped active nanoparticles can penetrate the dentinal tubules & enter accessory canals to ensure that all the spaces are effectively sealed [22].

Hybrid Root Seal

 It is a commercially available fourth generation selfadhesive dual-cure sealer, available in the powder-liquid form. It is an insoluble, radiopaque material that can be used either with resilon or Gutta-percha. The liquid comprises of 4-META, monofunctional methacrylate monomers and photo-initiators, while the powder consists of a mixture of zirconia oxide filler, silicon dioxide filler and polymerization initiators. 4-META is able to promote monomer diffusion into the acid-conditioned and underlying intact dentin and produces functional hybridized dentin with polymerization [23,24]. The formation of the hybrid dentin is the major mechanism of bonding and also the high quality hybridized dentin resists acidic challenges [25]. However, polymerization shrinkage is inherent to methacrlyate resin-based sealers that tend to produce debonding at the resin-dentin interface.

Gutta Flow 2 Sealer

 This is a modification of the original Gutta flow sealer which was available in the cartridge form. The excellent flow of this material made it the sealer of choice. However, the larger armamentarium required was a drawback. Of late, Gutta Flow 2 has been introduced which is available in the syringe form and has an excellent property of slight expansion after mixing which helps in better sealing.

 iRoot SP/EndoSequence BC Sealer

 The manufactures of these sealers claim the ability to form hydroxyappetite during the setting process and ultimately create a chemical bond between dentinal wall and the sealer [26,27]. These are convenient, premixed, ready-to-use, injectable white cement paste developed for permanent root canal filling and sealing applications. These are insoluble, radio opaque and aluminium free material based on a calciumsilicate composition, which requires the presence of water to set and harden. Dentin is composed of approximately 20% (by volume) of water and “iRoot SP” uses this water to initiate and complete its setting reaction [20]. It exhibits potent antimicrobial action, excellent biocompatibility, and significant stimulation of periodontal regeneration and is osteoconductive. These sealers are also termed as Bioceramic sealers in general.

However, till date, no sealer has been shown to be totally satisfactory for clinical use. All materials recommended for root canal filling have advantages and disadvantages and there is no single stereotype material or technique available so far, that fulfills all the possible requirements. The choice of sealer will depend on the core material and technique of obturation which in turn will depend upon the anatomy of the root canal. The choice of sealer may also be influenced by pre-existing periapical conditions for achieving prognostic healing outcome.

1. Lee, M. et al. “Current trends in endodontic practice: Emergency treatments and technological armamentarium.” Journal of Endodontics, vol. 35, no. 1, 2009, pp. 35–39.

2. Caicedo, R. and J.A. Von Fraunhofer. “The properties of endodontic sealer cements.” Journal of Endodontics, vol. 14, no. 11, 1988, pp. 527–534.

3. Viapiana, R. et al. “Interface of dentine to root canal sealers.” Journal of Dentistry, vol. 42, no. 3, 2014, pp. 336–350.

4. Bodanezi, A. et al. “Influence of Root Canal Sealer on the Radiographic Appearance of Filling Voids in Maxillary Single-Rooted Teeth.” Journal of Applied Oral Science, vol. 20, 2012, pp. 404–409.

5. Almeida, J.F.A. et al.“Filling of artificial lateral canals and microleakage and flow of five endodontic sealers.” International Endodontic Journal, vol. 40, no. 9, 2007, pp. 692–699.

6. Salz, U. et al. “Sealing properties of a new root canal sealer.” International Endodontic Journal, vol. 42, no. 12, 2009, pp. 1084–1089.

7. Jardine, A.P. et al.“The effect of final irrigation on the penetrability of an epoxy resin-based sealer into dentinal tubules: A confocal microscopy study.” Clinical Oral Investigations, vol. 20, no. 1, 2016, pp. 117–123.

8. Leakage, C. “Clinical and biological implications in endodontic success.” Endodontics Colleagues for Excellence, 2002, pp. 2–7.

9. Kim, S.Y. et al. “Quantitative microleakage analysis of root canal filling materials in single-rooted canals.” Scanning, vol. 37, no. 4, 2015, pp. 237–245.

10. Hauman, C.H. and R.M. Love. “Biocompatibility of dental materials used in contemporary endodontic therapy: A review. Part 2. Root-Canal-Filling Materials.” International Endodontic Journal, vol. 36, no. 3, 2003, pp. 147–160.

11. Desai, S. and N. Chandler. “Calcium hydroxide–based root canal sealers: A review.” Journal of Endodontics, vol. 35, no. 4, 2009, pp. 475–480.

12. Shrestha, D. et al. “Resilon: A methacrylate resin-based obturation system.” Journal of Dental Sciences, vol. 5, no. 2, 2010, pp. 47–52.

13. Kim, Y.K. et al. “Critical review on methacrylate resin–based root canal sealers.” Journal of Endodontics, vol. 36, no. 3, 2010, pp. 383–399.

14. Lotfi, M. et al. “Resilon: A comprehensive literature review.” Journal of Dental Research, Dental Clinics, Dental Prospects, vol. 7, no. 3, 2013, pp. 119.

15. Al-Haddad, A. and Z.A. Che Ab Aziz. “Bioceramic-based root canal sealers: A review.” International Journal of Biomaterials, 2016.

16. Primus, C.M. et al.“Bioactive tri/dicalcium silicate cements for treatment of pulpal and periapical tissues.” Acta Biomaterialia, vol. 96, 2019, pp. 35–54.

17. Tyagi, S. et al. “Evolution of root canal sealers: An insight story.” European Journal of General Dentistry, vol. 2, no. 3, 2013, pp. 199–218.

18. Huffman, B.P. et al.“Dislocation resistance of proroot endo sealer, a calcium silicate-based root canal sealer, from radicular dentine.” International Endodontic Journal, vol. 42, no. 1, 2009, pp. 34–46. https://doi.org/10.1111/j.1365-2591.2008.01490.x

19. Gutmann, J.L. Grossman’s Endodontic Practice. 13th ed., 2016.

20. Tay, F.R. and D.H. Pashley. “Monoblocks in root canals: a hypothetical or a tangible goal.” Journal of Endodontics, vol. 33, no. 4, 2007, pp. 391–398.

21. Garrido, A.D.B. et al. “Laboratory evaluation of the physicochemical properties of a new root canal sealer based on copaifera multijuga oil-resin.” International Endodontic Journal, vol. 43, no. 4, 2010, pp. 283–291. 

22. Ari, H. et al. “Sealing ability of hybrid root SEAL (MetaSEAL) in conjunction with different obturation techniques.” Oral Surgery, Oral Medicine, Oral Pathology, Oral Radiology, and Endodontology, vol. 109, no. 6, 2010, pp. e113–e116. https://doi.org/10.1016/j.tripleo.2010.02.016

23. Akman, M. et al. “Evaluation of gaps or voids occurring in roots filled with three different sealers.” European Journal of Dentistry, vol. 4, no. 2, 2010, pp. 101–109.

24. Marin-Bauza, G.A. et al. “Physicochemical properties of methacrylate resin–based root canal sealers.” Journal of Endodontics, vol. 36, no. 9, 2010, pp. 1531–1536. https://doi.org/10.1016/j.joen.2010.05.002

25. de Miranda Candeiro, G.T. et al. “Evaluation of radiopacity, ph, release of calcium ions, and flow of a bioceramic root canal sealer.” Journal of Endodontics, vol. 38, no. 6, 2012, pp. 842–845. https://doi.org/10.1016/j.joen.2012.02.029

26. Chen, C.C. et al. “Physicochemical properties of calcium silicate cements for endodontic treatment.” Journal of Endodontics, vol. 35, no. 9, 2009, pp. 1288–1291. https://doi.org/10.1016/j.joen.2009.05.036

27. Camilleri, J. “Hydration characteristics of calcium silicate cements with alternative radiopacifiers used as root-end filling materials.” Journal of Endodontics, vol. 36, no. 3, 2010, pp. 502–508. https://doi.org/10.1016/j.joen.2009.10.018