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ORIGINAL RESEARCH
Year : 2013  |  Volume : 5  |  Issue : 1  |  Page : 9-13

Apical sealing ability of two novel root canal sealers: An ex-vivo study


Department of Conservative Dentistry and Endodontics, Punjab Government Dental College and Hospital, Amritsar, Punjab, India

Date of Web Publication9-Jun-2014

Correspondence Address:
Vimal K. Sikri
Department of Conservative Dentistry and Endodontics, Punjab Government Dental College and Hospital, Amritsar, Punjab
India
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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/2231-0754.134130

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   Abstract 

Objective: The objective was to compare the sealing ability of two root canal sealers viz.: Hybrid Root SEAL (Sun Medical, Tokyo, Japan) and iRoot SP (Innovative BioCeramix Inc., Vancouver, Canada). Materials and Methods: A sample of 60 permanent single rooted, human maxillary central incisors of similar sizes was selected for the study. The teeth were decoronated and randomly divided into two groups viz.: Group A and Group B, comprising of thirty teeth each. In Group A, Hybrid Root SEAL and Group B, iRoot SP were used as root canal sealers along with Gutta-percha cones using lateral condensation technique to obturate the canals. After obturation roots were covered with nail paint except 2.0 mm of root and stored in 0.5% methylene blue dye for 1 week. The teeth were immersed in 10 ml of 65% nitric acid for complete dissolution and subsequently subjected to UV spectrophotometer to quantify the concentration of the dye in each sample. The data were analyzed using the unpaired t-test. Results: The mean dye leakage value in Group B (0.368) was less as compared to Group A (0.408). However, statistically the difference was nonsignificant (P = 0.053). Conclusion: There was no statistically significant difference among the two groups.

Keywords: Dye leakage, Hybrid Root SEAL, iRoot SP, spectrophotometer


How to cite this article:
Setia P, Sikri VK, Sroa RB, Sidhu B. Apical sealing ability of two novel root canal sealers: An ex-vivo study . J Int Clin Dent Res Organ 2013;5:9-13

How to cite this URL:
Setia P, Sikri VK, Sroa RB, Sidhu B. Apical sealing ability of two novel root canal sealers: An ex-vivo study . J Int Clin Dent Res Organ [serial online] 2013 [cited 2019 Jul 19];5:9-13. Available from: http://www.jicdro.org/text.asp?2013/5/1/9/134130


   Introduction Top


The hermetic sealing of the root canal by means of a three-dimensional obturation of the pulp space constitutes the key factor for successful endodontic therapy. Ingress of tissue fluids, bacteria and their by-products from the oral cavity into the canal space may lead to re-infection and failure of endodontic treatment. Moreover, micro-organisms may remain active in the dentinal tubules even after meticulous preparation of the root canal. Thus, perfect seal of the root canal space is mandatory to prevent the bacteria and their endotoxins from reaching the root apex. Incomplete obturation and subsequent apical leakage has been reported to be the common cause of endodontic failure.

A variety of materials are available for root canal obturation; however, the Gutta-percha cones along with the sealer remains the most accepted choice of the clinician. As Gutta-percha does not bond to root canal walls, the use of sealers along with well-adapted Gutta-percha has been considered mandatory. The major function of a root canal sealer is to fill up irregularities and minor discrepancies between the Gutta-percha and the root canal wall. It also fills patent accessory canals, if present. The application of sealer fills imperfections and increases adaptation of the root filling to the canal walls, failing which the chances of leakage and failure increase. It has been documented that teeth obturated with Gutta-percha along with sealer display a better seal than those obturated without sealer. [1],[2] Different types of sealers have been used in conjunction with Gutta-percha for root canal obturation with varied success. [3],[4],[5]

Ideally, root canal sealer should be biocompatible, antibacterial, nontoxic, radiopaque, and dimensionally stable, should have good adhesion and should eliminate the interface between the Gutta-percha and the dentinal walls completely. Leakage, may however, occur at the interfaces between the sealer and dentin, and sealer and Gutta-percha.

Harnessing the development in bonding dentistry in recent years, several methacrylate resin-based sealers have been introduced. The fourth generation methacrylate based sealers are functionally analogous to a similar class of recently introduced self-adhesive resin luting composites in that they have further eliminated the separate etching/bonding step. Hybrid Root SEAL (Sun Medical, Tokyo) is the first commercially available fourth generation self- adhesive dual- cure sealer. Available in the powder-liquid form, it is insoluble, radiopaque material that can be used either with resilon or Gutta-percha. Liquid comprises of 4-META (methacryloyloxyethyl trimellitate anhydride), monofunctional methacrylate monomer and multifunctional methacrylate monomers and photo-initiators. The powder consists of a mixture of zirconium 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. [6],[7] The formation of hybridized dentin is the major mechanism of bonding and also the high-quality hybridized dentin resists acidic challenges. [8] However, polymerization shrinkage is inherent to methacrylate resin-based sealers that tend to produce de-bonding at the resin-dentin interface.

Recently, a new root canal sealer, "iRoot SP" (Innovative BioCeramix Inc., Vancouver, Canada), also known as EndoSequence BC sealer (Brasseler, Savannah, GA, USA), has been introduced to the market that claims to form hydroxyapatite during the setting process and ultimately create a chemical bond between dentinal wall and the sealer. [9],[10] It is a convenient, premixed, ready-to-use injectable white hydraulic cement paste developed for permanent root canal filling and sealing applications. It is an insoluble, radiopaque and aluminum free material based on a calcium silicate 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. [11] It exhibits potent antimicrobial action, excellent biocompatibility, significant stimulation of periodontal regeneration and is osteoconductive.

Since the literature is deficient as regard the sealing ability of "iRootSP" root canal sealer, the purpose of this study was to evaluate the apical sealing ability of this newer material in comparison with "Hybrid Root SEAL" when used along with conventional Gutta-percha cones.


   Materials and methods Top


Sixty permanent maxillary incisors with straight root canals were selected for the study. Teeth with caries, cracks and immature roots were excluded from the study. The obtained teeth were cleaned off of soft tissues and calculus deposits, followed by stored in 10% formalin at room temperature. All the teeth were sectioned from cemento-enamel junction. The working length was determined by passing a #15 K file into the root canal until the tip was visible at the apical foramen and then subtracting 1.0 mm from the total length. The root canal system was cleansed and shaped to the apical foramen to the size of a No. 40 K-type file. The rest of each canal was flared by the step-back filling technique. The canals were irrigated with a 2.5% solution of sodium hypochlorite before cleansing and after use of each file.

The prepared teeth were randomly divided into two groups, viz., Group A and Group B comprising of thirty teeth each.

In Group A, Gutta-percha cones were used with "Hybrid Root SEAL" (Sun Medical, Tokyo, Japan) as root canal sealer. The sealer was freshly prepared immediately before its use. Three drops of Hybrid Root SEAL liquid and one cup of Hybrid Root SEAL powder were mixed on a mixing pad. The homogenous mixture was introduced to the root canal using paper point and placed into canal up to the working length. Subsequently obturation was carried out using lateral compaction technique. The excess cones were removed with the help of a warm burnisher. The coronal end of root filling was light cured for 40 s to create immediate coronal seal. The access cavity was subsequently sealed with intermediate restorative material (Orafil-G).

In Group B, Gutta-percha cones were used with "iRoot SP" (Bioceramix, Vancouver, Canada) as sealer. The premixed sealer available in syringe form was placed into the root canal using a dispensing tip. The master Gutta-percha cone was coated with the sealer and introduced apically into the canal. The obturation was carried out using lateral compaction technique. The excess cones were removed with the help of a warm burnisher. The access cavity was sealed with intermediate restorative material (Orafil-G).

The treated roots were covered with two coats of nail polish, except the 2.0 mm apically [Photograph 1]. The specimens were immersed in 0.5% methylene blue dye.



After 1 week, all the teeth were washed with tap water to remove excess dye and were dried. Nail polish was scraped off from all the surfaces.

After dye penetration procedure, each sample was kept in a closed vial containing 10 ml of 65% nitric acid for complete dissolution [Photograph 2] that took 4 days. Following this, 4.0 ml sample of each solution was placed into a UV light spectrophotometer to quantify, via light absorption, the concentration of dye in each sample.



Statistical analysis

The dye leakage of both groups was analyzed using the unpaired t-test.


   Results Top


The mean value and standard deviation of the measurement of light absorption in both groups are shown in [Table 1]. The results of this study showed that the mean light absorption for Group A (Gutta-percha with Hybrid Root SEAL) was 0.403 and for Group B (Gutta-percha with iRoot SP) was 0.368 indicating that the mean leakage in Group B was less when compared to Group A. However, the difference was not statistically significant (P = 0.053). A graph showing mean absorption values is shown in [Figure 1].
Figure 1: Graphic representation of light absorbance of two groups

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   Discussion Top


Approximately, 60% of all endodontic failures can be attributed to incomplete or defective sealing of the root canal. [12],[13] It is, therefore, necessary to study the efficacy of various sealing cements being introduced everyday with claims of ideal sealing abilities.

In this study, Hybrid Root SEAL and iRoot SP were used as root canal sealers. Hybrid Root SEAL, is a self-etching, self-adhesive, fourth generation resin-based sealer and iRoot SP is another novel sealer based on calcium silicate chemistry. Both the sealers have been claimed to present with the superior flow that facilitates spread through intricacies of root canal. [14],[15] The highest flow obtained with Hybrid Root SEAL could be due to the presence of 4-META that has one hydrophilic and other hydrophobic radical, probably responsible for the decrease of the sealer viscosity. [16] While in iRoot SP, the incorporation of nanoparticle size facilitates its better spread. [9] The sealing characteristics of Hybrid Root SEAL are attributed to the formation of hybridized dentin that provides the better seal with root dentin whereas iRoot SP sets in the presence of water and achieves excellent adhesion to the canal's wall by forming a chemical bond with dentin.
Table 1: Statistical evaluation of mean light absorbance in the two groups

Click here to view


In the current study, Hybrid Root SEAL and iRoot SP sealers were used along with Gutta-percha cones. The conventional Gutta-percha techniques along with various sealers have been shown to give similar or superior results in terms of sealing ability when compared to Hybrid Root SEAL/Resilon. [17] In both groups, root canal preparation was carried out with step-back technique. Step-back technique was chosen as it produced a significant increase in canal space and was more effective in removing predentin and debris and also planning the canal walls. [18]

Methylene blue was used as the dye in the present experimental set-up based on dye clearance method. It was preferred over India ink or other commonly used dyes in leakage experiment because of its smaller molecular size, which resulted in superior penetration ability, and its better performance during the measurement of volumetric microleakage. [19],[20] Moreover, it is easily detectable under visible light and is able to diffuse easily. [21],[22] Out of the plethora of methods available to assess sealing ability, the dye extraction method or the clearing technique is the most widely employed one owing to its simplicity and precision. The clearing technique has been found to afford the largest volume of information on the morphology of the sealed canal, allowing three-dimensional visualization of the root canal, the degree of filling, and the possible condensation defects. [3],[23] To add on, the aforementioned technique facilitates the observation of lateral and accessory canals and clearly reflects the relation between the sealing material and apical foramen. [24]

Results of this study show that the mean leakage in Group A (Hybrid Root SEAL) was more as compared to Group B (iRoot SP).

The slight better performance of iRoot SP can be explained on the basis of its low particle size, hydrophilicity and low contact angle which enable the cement to spread easily over the dentin walls of the root canal and get inside and fill the lateral microcanals. In addition, it also has a significant expansion of 0.20%. [25] These features lead to the formation of a gap free chemical bond between the sealer and the dentinal walls that makes it an effective sealer. However, Hybrid Root SEAL being a methacrylate based sealers inherently undergo polymerization shrinkage coupled with high C-factor inside the root canals. Immediate light-curing from the coronal side of the roots may also create a large polymerization stress during setting by preventing flow of resin-based sealers and may lead to de-bonding of the resin from the root canal walls, which results in gap formation and subsequently affecting the sealing ability of the sealer. [26] The result is in accordance to the in vitro study conducted by Zhang et al. [27] where in iRoot SP performed better than a resin-based sealer AH Plus in its sealing ability. Belli et al. [28] in vitro study found that Hybrid Root SEAL performed equal to AH Plus as regard sealing ability.

However, statistically nonsignificant difference was found between the two sealers regarding dye leakage. Ulusoy et al. [29] compared the effects of these two root canal sealers on fracture resistance of simulated immature teeth and observed that both iRoot SP and Hybrid Root SEAL reinforced the simulated immature roots against fracture when used with either Gutta-percha or resilon equally. Both the sealers though based on different setting mechanisms have shown promising clinical results as endodontic sealers, as confirmed by various studies.


   Conclusion Top


From this study, it can be inferred that both sealers, iRoot SP and Hybrid Root SEAL hold equal promising potential in terms of their sealing ability as a root canal sealer. Since, iRoot SP is less toxic, [30] easy to manipulate and possesses regenerative abilities [31] compared to Hybrid Root SEAL, it may be recommended for clinical use. However, before any definite conclusion can be drawn further studies should be encouraged to evaluate the long term efficacy of these sealers.

 
   References Top

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4.Barkhordar RA, Bui T, Watanabe L. An evaluation of sealing ability of calcium hydroxide sealers. Oral Surg Oral Med Oral Pathol 1989;68:88-92.  Back to cited text no. 4
    
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26.Mai S, Kim YK, Hiraishi N, Ling J, Pashley DH, Tay FR. Evaluation of the true self-etching potential of a fourth generation self-adhesive methacrylate resin-based sealer. J Endod 2009;35:870-4.  Back to cited text no. 26
    
27.Zhang W, Li Z, Peng B. Assessment of a new root canal sealer's apical sealing ability. Oral Surg Oral Med Oral Pathol Oral Radiol Endod 2009;107:e79-82.  Back to cited text no. 27
    
28.Belli S, Ozcan E, Derinbay O, Eldeniz AU. A comparative evaluation of sealing ability of a new, self-etching, dual-curable sealer: Hybrid root SEAL (MetaSEAL). Oral Surg Oral Med Oral Pathol Oral Radiol Endod 2008;106:e45-52.  Back to cited text no. 28
    
29.Ulusoy ÖÝ, Nayýr Y, Darendeliler-Yaman S. Effect of different root canal sealers on fracture strength of simulated immature roots. Oral Surg Oral Med Oral Pathol Oral Radiol Endod 2011;112:544-7.  Back to cited text no. 29
    
30.Loushine BA, Bryan TE, Looney SW, Gillen BM, Loushine RJ, Weller RN, et al. Setting properties and cytotoxicity evaluation of a premixed bioceramic root canal sealer. J Endod 2011;37:673-7.  Back to cited text no. 30
    
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