ENDODONTIC SEALERS CLASSIFICATION AND TYPES).pptx

ENDODONTIC SEALER , CLASSIFICATION AND TYPES

1. ENDODONTIC SEALERS GUIDED BY DR. ANURAG JAIN DR. SONAL BANSAL DR. SAURABH MANKELIYA DR. AMIL SHARMA DR.TANYA KOHLI SECOND YEAR PG

2. CONTENTS INTRODUCTION HISTORY CLASSIFICATION CONCEPTS/MECHANISM OF SETTING COMPOSITION OF VARIOUS SEALERS LITERATURE REVIEW- PROPERTIES OF SEALERS SUMMARY CONCLUSION REFERENCES

3. INTRODUCTION A successful root canal therapy requires complete obturation of the root canal system, thus achieving a fluid tight seal. The current accepted method of obturation employs a solid or semisolid core such as gutta-percha and a root canal sealer. Gutta-percha has no adhesive qualities to dentin regardless of the obturation techniques used. Therefore, root canal sealers play a major role in achieving the fluid tight seal by filling the accessory and lateral canals, voids, spaces and irregularities between gutta-percha.

4. The choice of sealer is not only dependent on its ability to create a sound seal, but it must also be well tolerated by the peri-radicular tissues and be easy to manipulate to achieve its optimum physical properties. Even though predictable clinical results have been obtained with the use of non-bonding root canal sealers, there has been a continuous search for alternative sealers that bonds to root canal dentin as well as filling materials. The quality of the seal obtained with gutta-percha (GP) and conventional zinc oxide eugenol (ZOE) sealers is quite far from being perfect. 

5. GP and conventional sealer limitations: Hence, several new resin cement sealants have been developed to be used instead of ZOE, thereby improving the root canal seal and imparting it more strength as compared to the conventional materials. 

6. PROPERTIES OF SEALERS

7. HISTORY

8. CLASSIFICATION

9. MESSING’S CLASSIFICATION Diaket – A N2 Endomethasone SPAD Iodoform paste Riebler’s paste Mynal cement Ca(OH)2 paste (Lanes 1962) Ca(OH)2 paste (Frank, 1962) ( Biocolex ) Endofloss NON- EUGENOL EUGENOL MEDICATED

10. COHEN’S CLASSIFICATION

11. HARTY FJ’S CLASSIFICATION 1. Zinc oxide eugenol based 2. Resin based 3.GP based cements: Solutions of GP in organic solvents. Eg : Chloropercha , Eupercha 4. Dentin adhesive materials Eg : cyanoacrylate cements, GIC, polycarboxylate cements, CaPo4, composite materials.

12. 5. Materials to which medicaments have been added: a. those in which strong disinfectants have been added to reduce post operative pain. Eg : paraformaldehyde, corticosteroid preparations . b. those in which calcium hydroxide has been added to induce cementogenesis and dentinogenesis at the foramen, creating a permanent biological seal. Eg : calcibiotic root canal sealer (CRCS), biocalex , sealapex

13. METHACRYLATE RESIN BASED SEALERS:

14. BASED ON COMPOSITION

15. MECHANISM OF SETTING

16. CHELATE FORMATION : Several luting agents set by means of a chelation reaction , by forming metal complexes with the polydentate (usually organic) ligands. Two of the most common chelates used in dentistry are eugenolates and salicylates. For eugenolates , the setting reaction starts with water that hydrolyzes the zinc oxide to form zinc hydroxide . The zinc hydroxide and eugenol chelate and solidify . For salicylates , the ion is calcium , usually formulated using calcium oxide . Fatty acids have also been used as ligands, in conjunction with zinc oxide .

17. 1. Zinc oxide-eugenol-based sealers The zinc oxide-eugenol sealer formula developed by Rickert and Dixon in 1931 became Kerr sealer , and the formula developed by Grossman in 1936 became Proco -Sol sealer ( StarDental , Lancaster, PA, USA). ZOE sealers contain zinc oxide powder and eugenol liquid , an essential oil derived from cloves.

18. Grossman’s original formula contained zinc oxide, staybelite resin, bismuth subcarbonate , barium sulfate , and sodium borate (anhydrous) with eugenol as the liquid component. It has been marketed as Procosol sealer , as well as other product names. Roth’s 801 sealer (Roth’s Pharmacy, Chicago, IL) is essentially the same as Grossman’s original formulation, with the substitution of bismuth subnitrate for bismuth subcarbonate . Eugenol is used as the liquid of the sealer.

19. Rickert’s formula was an early zinc oxide-containing sealer. Its major drawback was the staining of tooth structure from the silver that was used for radiopacity. It was marketed as Kerr’s Pulp Canal Sealer (Sybron Endo/Kerr, Orange, CA). A major disadvantage was its rapid setting time , especially with heat and in regions with high temperatures and high humidity. To overcome this, Pulp Canal Sealer EWT (Extended Working Time) (Sybron Endo/Kerr) was introduced with a working time of 6 hours

20. Tubli-Seal (Sybron Endo/Kerr) is a two-paste system contained in two separate tubes. Developed as a non-staining alternative to the silver-containing Pulp Canal Sealer. Tubli-Seal is easy to mix but has the disadvantage of rapid setting time. Tubli-Seal EWT has the same properties as the regular setting Tubli-Seal but has an extended working time

21. Wach’s cement (Roth International Inc., Chicago, IL) consists of a powder of zinc oxide, bismuth subnitrate, bismuth subiodide , magnesium oxide, and calcium phosphate. The liquid contains oil of cloves, eucalyptol, Canada balsam, and beechwood creosote. The liquid gives Wach’s cement a rather distinctive odor of an old-time dental office. It has the advantage of having a smooth consistency, and the Canada balsam makes the sealer tacky.

22. Medicated Canal Sealer ( Medidenta International, Inc.) was developed by Martin . This sealer contains iodoform for antibacterial purposes and is to be used with MGP gutta-percha, which also contains 10% iodoform.

23. When mixed and placed in moist root dentin, the zinc oxide and eugenol form an amorphous gel and the residual zinc oxide powder in the gel, forms a rigid matrix. A ZOE-containing paraformaldehyde sealer was developed but was unsuccessful because formaldehyde caused coagulative necrosis , disrupted local repair of affected areas and was toxic to peri-radicular tissues and hence contraindicated . Sargenti introduced N2 sealer in 1973 , which contained lead and mercury . These metals were reported to have migrated to distant organ systems, from the radicular spaces, therefore it was not cleared by the U.S. Food and Drug Administration.

24. ZOE sealers:

25. 2. Salicylate-based sealers Salicylate-based sealers are referred by their marketed therapeutic additives instead of their composition. For example, Sealapex (Kerr) and Apexit / Apexit Plus ( Ivoclar Vivadent , Schaan , Lichtenstein) are examples of a calcium-hydroxide-containing salicylate sealers . Calcium hydroxide [Ca(OH)2] is both alkaline and antimicrobial , desirable qualities for a therapeutic sealer.

26. However, calcium hydroxide does not set and is soluble in water. It must be used within a matrix to be an effective sealer. Sealers containing calcium hydroxide were intended to promote osteogenesis and cementogenesis as well as create an antimicrobial environment . The solvation of calcium hydroxide is required if therapeutic effects are to be achieved. MTA Fillapex (Angelus, Londrina, Brazil) is a unique salicylate resin based sealer that contains 15% MTA powder. It should not be regarded as a tricalcium silicate (MTA, a bioactive ceramic) sealer since its composition is primarily resin.

27. CRCS ( Calciobiotic Root Canal Sealer; Coltene / Whaledent / Hygenic , Mahwah,NJ )is a calcium hydroxide containing sealer with a ZOE–eucalyptol base. It is a slow setting sealer, especially in dry or in humid climate. It may require up to 3 days to fully set. Beltes et al. did an in vitro evaluation of cytotoxicity of calcium hydroxide-based root canal sealers and reported that, Sealapex > CRCS > Apexit . Vitapex (NEO Dental International, Inc, Federal Way, WA) is a sealer, which was developed in Japan, and contains, not only calcium hydroxide, but also 40% iodoform and silicone oil among other ingredients.

28. 3. Fatty acid-based sealer Fatty acids are used instead of eugenol as chelating agents , although the structure is less defined and consistent than with eugenolates and salicylates. Canals-N (Showa Yakuhin Kako ) is a fatty acid-zinc oxide sealer that uses linoleic acid, iso-stearic acid, and rosin . Nogenol (GC America, Alsip, IL, USA) is another fatty acid-zinc oxide sealer made with lauric acid . to overcome the irritating effects of eugenol. It is a two-tube, base and catalyst system. Hydrogenated rosin, methyl abietate, lauric acid, chlorothymol , and salicylic acid in the catalyst accelerate the setting time.

29. IONOMER FORMATION 1. Glass ionomer-based sealers Glass ionomer sealers are made by mixing fine silicate glass powder with polyacrylic and related acids . When mixed, they form repeating subunits of organic monomer and inorganic ions, creating an ionomer. Recent developments in experimental GIC sealer formulations are KT-308, ZUT and Activ GP.

30. KT-308 is conventional GIC with increased radiopacity and extended working time. ZUT is KT-308 combined with antimicrobial agent , a silver containing zeolite (0.2-20% weight). Activ GP ( Brasseler USA, Savannah, GA) consists of a glass ionomer impregnated gutta-percha cone with a glass ionomer external coating and a glass ionomer sealer. They are available in 0.04 and 0.06 tapered cones.

31. This single cone technique is designed to provide a bond between the dentinal canal wall and the master cone to form a monoblock . Advantages: It is technically less demanding than traditional methods of effecting apical seal. It has an inherent potential for providing a more stable apical seal. Due to bonding properties, glass ionomer may provide physical support for resisting root fracture.

32. Short working time and fast set are both factors, which contribute to the fact that GICs are often used in combination with a single cone technique. The single cone technique in combination with GIC might therefore be the reason for the more extensive leakage . It has been shown that, it takes more time to remove a GIC sealer than a conventional sealer during retreatment procedures. When GIC sealer is used in combination with gutta-percha, gutta-percha can be dissolved and then the GIC can be removed ultrasonically from the canal without leaving excessive amounts of residue on the canal walls.

33. Polymer Formation By Addition Reaction Silicone and epoxy resin-based sealers both polymerize by addition reactions. Addition reactions are differentiated from other polymerization reactions because they co-generate byproducts ( usually water). Silicone-based sealers form a three-dimensional polymer network by addition polymerization as a series of cross-linkage between divinyl polysiloxane and poly methyl hydrosiloxane with a platinum salt as the catalyst . Epoxy resin-based sealers follow a more traditional organic addition reaction, where epoxide monomers react with amines to create a rigid material .

34. 1. Silicone-based sealers In 1972, Davis et al . used injectable silicone impression material into the prepared root canals. They are composed of polymethyl vinyl siloxane containing a platinum salt and polymethyl hydrogen siloxane and set by addition reaction between vinyl groups attached to polydimethylsiloxane chain and hydrosilyl groups attached to polydimethylsiloxane chain , forming polymer. GuttaFlow is triturator -mixed and requires the use of a single master cone whereas GuttaFlow 2 and RoekoSeal are auto-mix .

35. Endofill is an injectable silicone resin sealer used in combination with core material or as a sole filling material to be injected into canal space with pressure syringe. It contains silicon monomer, silicon based catalyst and bismuth subnitrate ( radiopacifier ). The catalyst is tetraethyl orthosilicate and poly-dimethyl siloxane and the setting time is 8-90 minutes . It has low viscosity, exhibit good adaptation to the tooth structure and low toxicity. However it is difficult to remove from canal and exhibit shrinkage upon setting.

36. RoekoSeal is available in an automix syringe/ single dose package . It has excellent flow properties and is extremely biocompatible . The extremely low film thickness of 5 μm allows the sealer to flow into tiny crevices and dentinal tubules. The solubility - virtually zero and is highly radiopaque for an excellent x-ray evaluation. It does not shrink but actually expands slightly (0.2%) - outstanding seal with the canal walls. It does not form a chemical bond with dentin, which is an advantage for retreatment.

37. Gutta percha milled to a low grain size is mixed into components of the silicone sealer [Gutta-flow ( Coltene Dental, USA)]. It has extraordinary chemical and physical properties that offer maximum sealing quality and biocompatibility . It contains small gutta-percha particles with a size of <30μ as filler . The material is flowable and sets within 10 min . The material flows into the smallest dentinal tubules, because of the small particle size (<0.9 μm ) of the GuttaFlow matrix filler.

38. 2. Epoxy resin-based sealers Epoxy resin was invented in 1938 by P. Castan , a Swiss chemist of de Trey (Zurich, Switzerland), and AH 26 was developed by the same company during 1940s . In 1993, Spångberg et al. reported that AH 26 releases formaldehyde , which recommended transition from AH 26 to AH Plus , which does not release formaldehyde. Other disadvantages are staining and an extended working time. On the other hand, AH 26 does not seem to be affected by moisture, and will even set under water.

39. AH 26 and AH Plus (Dentsply Sirona, Konstanz, Germany), are composed of low molecular weight epoxy resins and amines and set by addition reaction between epoxide groups attached to epoxy resins and amines to form polymer. AH 26 exists in a powder-paste mixture while AH Plus exists in a paste-paste mixture . When sold in an automatic mixing syringe, AH Plus is known as AH Plus Jet . In the United States, AH Plus and AH Plus Jet are sold as ThermaSeal Plus and Ribbon sealer, respectively.

40. AH Plus has thinner film thickness, decreased solubility, and is less cytotoxic than AH 26. Commercially available as: TopSeal in Europe, Central America, and South America. Adseal (Meta Biomed, Cheongju, Republic of Korea) Acroseal ( Septodont , Saint- Maur -des- Fossés , France) MM seal (Micro-Mega, Besançon , France)

41. AH Plus is a two paste system , delivered in two tubes and a new double barrel syringe . Working time - 4 hours, Setting time - 8 hours Film thickness - 26mm. It is thixotropic, radio opaque and has flow of 36 mm which perfectly meets the requirements of the ANSI/ADA (2000) standardization. It is characterized by very low shrinkage and by high dimensional stability .

42. Due to its excellent properties, such as low solubility, small expansion, adhesion to dentin and very good sealing ability , AH Plus is considered as a “ Gold Standard” sealer . Acroseal is also an epoxy resin based sealer containing 28% calcium hydroxide in its composition. It has shown to have antimicrobial activity against Enterococcus faecalis , low toxicity and adequate film thickness .

43. THE MONOBLOCK EFFECT Kittur et all stated in review article ‘ The monoblock concept in endodontics ’ The Modulus of elasticity and sealing ability are the two controversies associated with the monoblocks which do not contribute for the root fortification. Despite several draw backs in the theory it is said that the future of endodontics should focus on developing newer materials to attain a leak free hermetic sealing interface between the root canal wall and the obturating materials fulfilling the criterias required for the concept of monoblock . An ideal obturation material creating a monoblock should be nonmutagenic , noncarcinogenic , nonirritating and biocompatible to periradicular tissues. An in vivo study on guinea pigs was performed to check the biocompatibility of primary monoblock (MTA), secondary monoblock ( resilon ) and tertiary monoblock ( endorez ). A cytotoxicity evaluation revealed better biocompatibility and more viable cell count and moderate to severe levels of inflammation were seen with the three monoblocks tested .

44. HYDRATION Tricalcium silicate-based (MTA/ bioceramic ) sealers MTA is a ceramic cement , introduced by Torabinejad and White in the 1990s , based on the hydraulic powders of tricalcium silicate and dicalcium silicate . Calcium silicate cements and calcium hydroxide are bioactive ; that is both ceramics release calcium and hydroxide ions . The ions induce the formation of hydroxyapatite on their surface when body fluids (or synthetic body fluids) are present.

45. ProRoot MTA Gray (Dentsply Sirona, Johnson City, TN, USA) was the original MTA product, marketed in since 1997 , but it was only used as a root-end filling material or perforation fill, not as a sealer. Bismuth oxide, zirconia, tantalum oxide, barium zirconate have been used for radiopacity . Uses: perforation repair, retrograde root canal filling after an apicoectomy, pulp capping, and pulpotomies. Advantages: sealing by HA formation and biocompatibility.

46. Bioceramic based sealers include alumina, zirconia, bioactive glass, glass ceramics, hydroxyapatite, and calcium phosphates . They are categorized into two groups of calcium silicate based sealers (Mineral Trioxide Aggregate based and non MTA based) and calcium phosphate based sealers. Also, another categorization of bioceramic based sealers is available in two groups of bioactive and bioinert materials due to their interaction with the close, alive tissues. Bioactive materials , such as glass and calcium phosphate , interact with the surrounding tissue to encourage the growth of more durable tissues.

47. When mixed with water, tri and dicalcium silicate powders react and form a hydrated matrix with embedded calcium hydroxide . The calcium and hydroxide ions continue to release for about one month after setting. The high pH causes the phosphate ions in body fluids to precipitate hydroxyapatite at the surface. The tricalcium silicate materials are distinguished by their bioactivity ; that is, their ability to form hydroxyapatite on their surface and an osteogenic effect .

48. While ProRoot MTA is not suitable as an endodontic sealer, Grey & NeoMTA Plus ( NuSmile Avalon Biomed, Houston, TX, USA) are indicated for sealing . Three tricalcium silicate powder- liquid systems are known: NeoMTA Plus, BioRoot RCS, and Endo CPM.

49. The setting mechanism of single-paste tricalcium silicate-based sealers is water absorption from dentin tubules with the concomitant formation of HA at the surface within the canals . Commercially available as: iRoot SP (Innovative Bioceramix , Vancouver, Canada), EndoSequence BC ( Brasseler , Savannah, GA, USA), Total Fill BC (FKG Dentaire , La Chaux -de-Fonds, Switzerland), and Edge Endo Sealer (Edge Endo, Albuquerque, NM, USA.

50. EndoSequence BC Sealer is used with a single-cone technique , a viable option for obturation in NSRCT. Other single-paste sealers containing tricalcium silicate and organic liquids are: CeraSeal (Meta Biomed), Endoseal MTA ( Maruchi , Gangwon-do, Republic of Korea), and Bio-C Sealer (Angelus). They are easy to use , despite their high cost .

51. Polymer Formation By Radical Polymerization Methacrylate resin-based sealers The first generation began with Hydron (Hydron Technologies, St. Petersburg, FL, USA),. Wichterle and Lim , contact lens researchers, developed Hydron in the 1960 . It was composed of 2-hydroxyethyl methacrylate polymer gel for injection in the canal without the need for a core , such as gutta-percha. However, because of its short working time, very low radiopacity , difficulty in removal from canals , and tendency to irritate the periapical tissues , it was discontinued in the 1980 s.

52. At the beginning of the 21st century , the desire for bonding between dentin and sealing materials gave way to the second generation of methacrylate sealers . EndoREZ ( Ultradent , South Jordan, UT, USA) is a dual cure sealer that does not require a dentin adhesive . Methacrylate resin was used without gutta percha to create a “ monoseal ”; that is, a sealer which binds to radicular dentin as well as the core obturation materials. A monoseal is achieved when the material creates a gapless interface between the dentinal wall and rigid core (also called a monoblock ).

53. Third-generation methacrylate-based sealers made use of formulations containing self-etching primers , beginning with Resilon /Epiphany ( Resilon Research, Madison, CT, USA); functionally, this addition is analogous to the “ all-in-one” adhesives used in restorative dentistry. The Resilon /Epiphany system was an alternative to conventional gutta-percha/sealer system. The Epiphany primer etched and conditioned the dentinal surface of the canal by demineralizing it and exposing the collagen matrix .

54. The contents of the primer allowed the Epiphany sealer to bond covalently to the dentinal surface during polymerization . The sealer also covalently bonded to the Resilon cone , thereby achieving the monoseal desired with methacrylate-based systems. The Resilon cones contained bioactive glass , which could be resorbed. Because the dentinal wall, sealer and cone are covalently bonded , they form a single unit, known as a monoblock .

55. RealSeal SE (Kerr) was a commercial product similar to Epiphany but with less etching ability than RealSeal . These systems are no longer sold because they were susceptible to degradation of their ester bonds. Fourth-generation methacrylate-based sealers include a combination of self-activating etchant, primer, and sealer. Hybrid Root SEAL (Sun Medical, Shiga, Japan), also commercialized as MetaSEAL ( Parkell , Edgewood, NY, USA) in the United States, is the first commercially available sealers of this generation.

56. Hybrid Root SEAL hybridized dentin is more resistant to low pH , which was most effective after EDTA irrigation and may reduce microleakage . Super-Bond RC Sealer ( Accel) (Sun Medical) is a commercially available methyl methacrylate-tributyl borane (MMA-TBB) resin sealer which uses TBB as an initiator and to induce interfacial polymerization of MMA at the dentin interface. TBB has been shown to cause graft polymerization of MMA onto dentin collagen, creating a collagen-MMA graft polymer .

57. Syudo and Hayashi in 2010 introduced a “ floating with accessory point technique ” using Super-Bond RC Sealer (Accel). The benefit of “floating” assures interfacial adhesion between dentin and the sealer for hermetic sealing . After placement of a floating master cone gutta-percha point, accessory points may be inserted to reduce voids/bubbles and increase interfacial contact for adhesion . They also noticed the mixed layer of the resin and gutta-percha at the interface of the canal walls, sealer, and gutta-percha bonded, creating monoblock .

58. Simultaneous treatment for root canal filling and core construction (STRC), a technique developed by Masaka et al ., uses MMA-TBB resin to adhere a fiber post system. The fiber post has an elastic modulus similar to dentin , unlike metal posts, making to more suitable for mimicking masticatory stress and strain . STRC uses the fiber post system replacing gutta-percha points with a minimum condensing force during the root canal obturation process. STRC is beneficial because it minimizes the number of patient clinical visits and may prevent vertical root fractures as a result of monoblock formation .

59. ANTIBACTERIAL METHACRYLATE RESIN-BASED A different approach was adopted in third generation MRB sealers by incorporating sustained antibacterial activity into the polymerized sealer. (Dr Satoshi Imazato , personal communication, July 2008). Both the primer and sealing resin contain the antibacterial resin monomer 12-methacryloyloxydodecyl pyridinium bromide (MDPB). Chlorhexidine releasing PMMA based sealers have been developed with the incorporation of 2-3 wt % CHX diacetate into the sealer powder.

60. CALCIUM PHOSPHATE-BASED SEALERS It is well known that calcium phosphate cement has a high biocompatibility because of its composition, almost identical to that of tooth and bone mineral. This makes the material useful when the cement is in contact with the vital tissues. Therefore, it has been suggested for endodontic therapy as root canal sealer. Eg : Capseal I, Bioseal , Apatite Root sealer (I, II, and III), Capseal II

61. Apatite root canal sealer is composed of hydroxyapatite and tricalcium phosphate and is available in 3 types based on difference in composition and use. Bioseal ( Ogna Lab Farma , Italy) is hydroxyapatite containing eugenol sealer. These sealers have favorable tissue responses, acceptable biocompatibility and good sealing abilities. Bae et al. reported that Capseal I and II have superior mineralization potential than other commercial root canal sealers. Capseal I and II produced pH and calcium ion release higher than or equal to those of Sealapex and Apatite root sealer .

62. LITERATURE REVIEW ON PROPERTIES OF SEALERS

63. 1. SETTING TIME & SOLUBILITY Setting time and solubility are critical components in the sealing ability of sealers. Slow setting times allow for sealer to more readily penetrate intricate canal morphology even after treatment. Faster setting times may be indicated in time sensitive situations, such as when obturation must be completed quickly or a post must be placed sooner.

64. SEALERS SETTING TIME SOLUBILITY ZOE BASED Proco -Sol - 40.5 min to 42 h, Tubli-Seal – 1hr. 3% solubility of sealers in distilled water, 5.19% in halothane IONOMER BASED Ketac Endo – 2.5 hrs 1.6% solubility in water with weight loss of less than 1% exposed for 10 min SILICONE BASED GuttaFlow - 17.4 min 0.13% solubility in water TRICALCIUM SILICATE BASED EndoSequence BC - 1month BioRoot RCS - 4hrs Bio-C - 3hrs CeraSeal - 3.5hrs BioRoot RCS and Total Fill BC sealer - higher solubility in distilled water

65. SEALERS SETTING TIME SOLUBILITY EPOXY RESIN BASED AH 26 – 34 hrs AH Plus – 8hrs AH PLUS - 0.16% solubility in water more soluble in halothane, yielding 68% weight losses METHACRYLATE BASED Super-Bond RC Sealer (Accel) – 42 mins EndoREZ and Epiphany, were shown to have 3.5–4% solubility in water, SALICYLATE-BASED Sealapex – 58 mins Sealapex met the solubility requirements. Apexit solubility in halothane was similar to ZOE sealers

66. In summary, setting times for most sealer types were acceptable and well above one hour, with an exception of silicone-based sealers , which had markedly shorter setting times. Solubility depends on the sealer matrix chemistry. For re-treatment, mechanical removal of a sealer will be useful for tricalcium silicate-based sealers and resin-based sealers.

67. 2. SEALING ABILITY Sealing ability is of utmost importance for a sealer. Although many microleakage studies have been published, direct comparison of each sealer is difficult because experimental condition was different in each experiment/research. In many papers each sealer was tested together with AH Plus. Thus it will be convenient to compare sealing ability of each sealer by using AH Plus as a standard. The relative degree of microleakage was calculated by length of microleakage of each sealer divided by that of AH Plus.

68. 3. ANTIMICROBIAL ACTIVITY Antimicrobial activity can be directly caused by a sealer, or indirectly by entombing bacteria. Any endodontic sealer that does make a hermetic seal functions to entomb bacteria within the canal and tubules, preventing communication of residual bacteria to the apical tissue. However, bacteria present at the apex may not be entombed, and would be killed by an antimicrobial endodontic sealer. Zinc oxide is a well-documented antimicrobial material because it forms a reactive oxygen species and interferes with bacterial membrane proteins.

69. SEALER ANTIMICROBIAL ACTIVITY ORGANISMS ZOE sealers Better compared to epoxy resin sealers Streptococcus mutans , Staphylococcus aureus, and Enterococcus faecalis Glass ionomer sealers Minimal activity inspite of fluoride release. Silicone-based sealers No antimicrobial activity Gutta Flow and Roekoseal Streptococcus mutans , Staphylococcus aureus, Staphylococcus epidermidis, and Enterococcus faecalis - X MTA based sealers Antimicrobial effect MTA and Portland cement = ZOE, salicylate ( sealapex ) and epoxy resin sealers (AH Plus) Facultative bacteria Obligate anaerobes - X Staphylococcus aureus, Enterococcus faecalis, Candida albicans. - X

70. SEALER ANTIMICROBIAL ACTIVITY ORGANISMS Tricalcium silicate-based Endo Sequence BC Sealer > ZOE and epoxy resin sealers They increase the local pH by release of calcium and hydroxide ions. Total Fill BC Sealer EndoSequence BC Sealer and ProRoot MTA > epoxy resin (AH Plus) and ZOE sealers Enterococcus faecalis effect on planktonic bacteria biofilms for Staphylococcus aureus and Enterococcus faecalis. Enterococcus faecalis Epoxy Resin Sealers AH Plus sealer > GuttaFlow AH Plus < MTA Fillapex (salicylate-based sealer) and CRCS (ZOE sealer). Zone of inhibition tests for AH Plus were comparable to ZOE sealers. AH Plus had the highest antibacterial however lasting only for 24hrs. planktonic and biofilm bacteria

71. SEALER ANTIMICROBIAL ACTIVITY ORGANISMS Methacrylate resin-based sealer Endo REZ had the strongest activity compared to AH Plus and Sealapex Calcium hydroxide-containing sealers CRCS > epoxy resin (AH Plus) and MTA sealers Calcium-hydroxide based sealers > zone of inhibition than ZOE sealers Supercal ( Ozdent , Sydney, Australia) > MTA and AH Plus sealers. Enterococcus faecalis

72. 4. BIOCOMPATIBILITY AND CYTOTOXICITY

73. SEALER BIOCOMPATIBILITY CYTOTOXICITY ZOE sealers Irritant - They activated a complement mediated immune response Non eugenol sealers - Canals-N29 and Nogenol were later introduced Cytotoxic - fibroblast cytotoxicity. Glass ionomer sealers Caused inflammation when implanted subcutaneously into rats, although it was not detectable after 3 months. (Fuji II, GC) had lower cytotoxicity when freshly mixed compared with resin (Chem-fil II, De Trey, Wiesbaden, West Germany). Fully set, GIC > Chem-fil II after setting, because of its fluoride ion release. low level of cytotoxicity over long periods of time, indicating they consist of very biocompatible material

74. SEALER BIOCOMPATIBILITY CYTOTOXICITY Tricalcium silicate-based EndoSequence BC Sealer have strong cell viability even decreasing LPS mediated inflammation. Osteoinductive properties and cytocompatibility: BioRoot RCS > Pulp Canal Sealer. BioRoot RCS and EndoSequence BC Sealer showed no cytotoxic effects on human bone marrow mesenchymal cells when compared to AH Plus Over 6 weeks, EndoSequence BC > AH Plus to osteoblast progenitors MTA was found to be cytotoxic in vivo in rats, two and seven weeks Silicone-based sealers Gutta Flow was determined to be biocompatible in a fibroblast incubation test. Less cytotoxic < Epoxy resin based (AH 26 and AH Plus) during the first 11 days of fibroblast suspension cultures, and similar cytotoxicity was measured after 24 hrs.

75. SEALER BIOCOMPATIBILITY CYTOTOXICITY Epoxy Resin sealers Limited biocompatibility High levels of inflammation have also been detected in periapical and subcutaneous tissues Unset epoxy sealers are genotoxic in mammalian cell mutation assays, attributed to residual monomer and formaldehyde. Set sealers- no genotoxic activity after 24 h. AH 26 release formaldehyde even two days after being mixed. AH Plus is modified such that formaldehyde is not released.

76. SEALER CYTOTOXICITY Methacrylate based sealers negligible - set, cytotoxicity - early in the setting process. Incompletely cured MMA - cytotoxic. TEGDMA, UDMA, HEMA and PEGDMA - time-dependent increases in cell death. EndoREZ > epoxy resin-based sealer (AH Plus) and a silicone-based sealer ( RoekoSeal ) Real Seal and EndoREZ > salicylate-based ( Apexit Plus) or epoxy resin-based sealer (AH Plus). However, in comparison with their epoxy resin-based counterparts (AH Plus), methacrylate-based sealers (Hybrid Root SEAL/ MetaSEAL and Super-Bond RC Sealer (Accel)) are less cytotoxic in plated cultures.

77. 5. BOND STRENGTH

78. REFERRED ARTICLES AND COMPARISON

79. SEALER PLACEMENT

80. CLINICAL IMPLICATION AND FUTURE DIRECTIONS

81. Pulp diagnosis as vital or necrotic is important for selection of an endodontic sealer for clinical use. In vital pulp (pulpitis) cases , the therapeutic effects of sealers are not necessary under the asepsis technique NSRCT , based on study by Kakehashi et al. Therefore, sealers which have shown effective sealing, are a good choice. While tricalcium silicate sealers show the least leakage , they have slow setting times. Therefore, tricalcium silicate sealers are not a good choice if post/core/build-up must occur on the same day together with endodontic obturation.

82. In necrotic pulp cases , especially cases with large apical radiolucency , the therapeutic effects of tricalcium silicate-based sealers are useful. A medicated sealer to kill bacteria should increase the chances of long-term success. Salicylate-based (calcium-hydroxide-containing ) are good choices if post/core/build-up is performed immediately after completion of endodontic obturation. A clinician has the responsibility to decide the top priority for the patient: good sealing or a therapeutic effect.

83. CONCLUSION In future, the importance of sealers will become more of a focus in clinical treatment. Clinicians will better understand the sealer’s role in preventing bacterial leakage , resulting in a successful outcome in endodontic practice. Compared to AH Plus, tricalcium silicate sealers showed the lowest relative microleakage among the sealers assessed, followed by silicone sealers and other non-AH Plus epoxy resin sealers. Tricalcium silicate sealers also exhibit the most favorable antimicrobial effect and excellent biocompatibility. Future sealers developed should ideally combine a hermetic seal with therapeutic effects .

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