Evaluation of the apical sealing ability of bioceramic sealer, AH plus & epiphany: An in vitro study

Abstract

Objective:

This in vitro study evaluated and compared the microleakage of three sealers; Endosequence bioceramic (BC) sealer, AH Plus and Epiphany.

Materials and Methods:

Study was done on 75 extracted human single rooted permanent teeth, which were decoronated and the root canals were instrumented. The specimens were randomly divided into three groups (n = 25) and obturated by continuous wave condensation technique. Group A: using Endosequence BC, Group B: using AH Plus sealer, Group C: using Resilon Epiphany system. Microleakage was evaluated using dye penetration method. Teeth were split longitudinally and then horizontally markings were made at 2, 4 and 6 mm from the apex. Dye penetration evaluation was done under stereomicroscope (30X magnification).

Results:

The dye penetration in Group B was more than in Group A and C in both vertical and horizontal directions, suggesting that newly introduced BC sealer and Epiphany sealer sealed the root canal better compared to AH Plus Sealer.

Conclusion:

Newer root canal sealers seal the root canal better but cannot totally eliminate leakage.

INTRODUCTION

Root canal treatment without obturation or with improper obturation is termed as incomplete root canal treatment. Ingle and colleagues radiographically studied endodontic success and failure; they indicated that 58% of treatment failures were due to incomplete obturation.[1] The three dimensional (3D) obturation is the primary objective of root canal therapy, the purpose of obturation in turn is to seal all “portals of exit”. Obturation impedes any sort communication between periapex, periodontal space and root canal.[2] thus entombing the micro-organisms and preventing re-infection by spread of microbial toxins.

Sealers can be a cause of root canal failure due to microleakage at sealer-dentin or sealer-core material interface.[2,3,4] Bonding of the sealer to the root canal dentin wall and formation of a monoblock can eliminate this drawback.

An ideal endodontic sealer should fulfil all ideal requisites. The tight seal at the apex can be enhanced, sealer bonds chemically to the dentinal wall of root canal, and mild expansion of the sealer improves its adaptation to the canal walls. It should be antibacterial and resistant to dissolution. One of such sealer is bioceramic (BC) sealer.[1]

BC sealer is a recently introduced sealer, composed of zirconium oxide, calcium silicates, calcium phosphate monobasic, calcium hydroxide, and various filling and thickening agents. The material is available in premixed calibrated syringes with intra-canal tips. As a hydrophilic sealer it utilizes moisture within the canal to complete the setting reaction and it does not shrink on setting.

The present study was undertaken to compare and evaluate the apical sealing ability of newly introduced BC sealer that is, Endosequence BC Sealer and two commonly used sealers — AH plus and Epiphany sealer.[5,6] The null hypothesis tested was that there are no differences in the apical sealing ability between the sealers groups tested.

MATERIALS AND METHODS

Source of data

The study was conducted in the Department of Conservative Dentistry and Endodontics and Department of Microbiology, MMNGH Institute of Dental Sciences, Belgaum, Karnataka, India, on 75 extracted human single rooted permanent teeth.

Materials and methodology

Seventy five extracted human single rooted permanent teeth with fully developed root apices, straight roots, free of cracks, caries, resorptive defects and fractures were selected for the study. After removal of the external debris, teeth were placed in 2.5% sodium hypochlorite solution for 2 hours and stored in normal saline. Teeth were decoronated 12 mm from the apex, canals were accessed. Instrumentation was done with 11 mm working length using a crown-down technique with Rotary Pro taper files (Dentsply Maillefer, Ballagigues, Switzerland) to F3. All the canals were irrigated with 10 mL of a freshly prepared solution of 5.25% sodium hypochlorite (NaOCl) and 17% EDTA solution alternatively between files and the final irrigation was done with normal saline. The canals were then dried with sterile paper points.

Obturation of canals

The specimens were randomly divided into 3 groups of 25 samples each.

• Group A: with GP, using Endosequence BC (Brasseler, Savannah, USA).

• Group B: with GP, using AH Plus sealer (Dentsply, De Trey Konstanz, Germany).

• Group C: with Resilon Epiphany system, i.e. Real Seal SE (SybronEndo, Korea).

After obturation by continuous wave condensation technique (E & Q Plus System; Meta Dental Corp, Korea), the coronal opening was sealed with glass ionomer cement, restorative type (Type 2, GC Gold Label, Japan). The samples were then stored in a humid atmosphere (Incubator) at 37°C for 24 hours. Later, the surfaces of the samples were dried and two layers of coloured nail varnish was applied on the surface 2 mm short of the apex. Roots were then suspended in freshly prepared 1% methylene blue for 72 hours. Following this, the roots were rinsed for 15 minutes under running tap water.

Preparation of specimens for microleakage evaluation

The varnish layers were scrapped off and the roots were split longitudinally parallel to the long axis with a diamond disc using a water coolant and markings were made at 2, 4 and 6 mm from the apex. The depth of dye penetration was examined under stereomicroscope (Magnus) at 30× magnification and microleakage associated with different root canal sealers was evaluated and values were obtained in units. These values were then converted to millimetres for vertical dye penetration and micrometers for horizontal dye penetration, using the following standard formulae –

Statistical analysis

The results were analysed by one way ANOVA, t-test and Newman-Keuls multiple post hoc procedures. Statistical significance was defined in advance as P < 0.05 using the SPSS9.0 for Windows (SPSS Inc, Chicago, IL, USA) statistical package.

RESULTS

Shows microleakage in three different groups. Tables 1-3 show the statistical analysis done.

Table 1.

Comparison of three groups with respect to vertical penetration of dye by one way ANOVA

Table 3.

Comparison of three groups (A, B, C) with horizontal penetration of dye at 2 mm, 4 mm and 6mm length scores by one way ANOVA

Table 2.

Pair wise comparison of three groups with respect to vertical penetration of dye by Tukeys multiple post hoc procedures

The results of this study showed that the vertical dye penetration was least for Group A and C, and highest for Group B with significant (P < 0.05) difference found between Group A and Group B, and Group B and Group C, there was no significant difference found between Group A and Group C. Pair wise comparison of three groups by Newman-Keuls multiple post hoc procedures was done for horizontal dye penetration, it showed, at 2 mm, the results were not significant, but at 4mm and 6mm there was a significant (P < 0.05) difference except for group A vs C at 6 mm.

DISCUSSION

As a consequence of the current results, the null hypothesis was rejected. The main objective of a root filling is to obturate the entire root canal system and produce an impervious apical seal. Obturation of a root canal is done by two materials one being the core and other is the sealer. Core is either cold or thermoplasticized, warm condensation multi phase (gutta-percha — sealer) technique is considered as “golden” standard for endodontic treatment, that result in a friction fit, “cork-in-the-bottle” type sealing.[7]

Various types of sealers are available, from Eugenol based, Non Eugenol to most recent being Calcium silicate sealers. Each of them have their own inherent drawbacks, still the search for ideal sealer is on.

To evaluate the sealing ability of sealers, tracers like dyes, radioisotopes, bacteria and their products, such as endotoxins and other methodologies like fluid filtration and dye extraction method have been used.[8] One of the commonly applied methods to evaluate the sealing ability of different root filling materials and techniques is based on linear measurement of dye penetration. Dyes like Eosin, Methylene blue, Black India Ink, Procion brilliant blue, etc are used. Methylene blue dye was used in this study as its molecular size is similar to bacterial by-products such as butyric acid which can leak out of infected root canals to irritate periapical tissues, also it is easy to use, pH manipulation and availability add to it advantages.[9,10] In our study the flow of methylene blue dye in the tooth through the apex, determined the result for the sealers evaluated. Methylene blue dye has the potential to enter the obturated canals through complex anatomies of apical third of the root canal or space between dentin-sealer-core material interfaces. The vertical and horizontal penetration of dye was measured in units by a stereomicroscope using micrometer eye-piece to achieve more accurate results.

Studies in past have evaluated the apical sealing ability of various sealers by different methods like antibacterial effectiveness, fluid filtration method and use of SEM, light microscope or digitally captured images for evaluation of sealer- dentin interface.[15] The present study was done to compare and evaluate the amount of apical leakage in root canal walls after obturation using three different root canal sealers, using dye penetration method.

Among various types of sealer used today AH plus has gained popularity due to its radiopacity, biocompatibility, ease to use and availability. AH Plus is an epoxy-bis-phenol resin based sealer that also contains adamantine and bonds to root canal.[11]

It is a two-component paste/paste root canal sealer. Since it contains resin and has faster setting time AH Plus tends to shrink and cause early debonding from the root canal wall.[12] AH plus has greater adhesion to root dentin than Epiphany, it can be likely due to the fact that, as an epoxy resin-based sealer, AH Plus has better penetration into the micro-irregularities because of its creep capacity and long setting time, which increases the mechanical interlocking between sealer and root dentin. But to contradict this there is inadequate bonding between the sealer and the gutta-percha point, allowing fluid leakage at this interface.[12] This was observed in our study, which could be one of the reason Group B recorded a mean value (8.0480) significantly more in vertical penetration of dye compared to Group A and Group C.

Resilon Epiphany Obturating system is known for its property of monoblock formation. It uses polymerizable methacrylate carboxylic acid anhydride (4-META) as the acidic resin monomer.[13] Epiphany sealer is a dual cure and bonds to a resilon core and root canal dentin simultaneously. Considering the bonding ability, there was no significant difference found by an scanning electron microscope (SEM) study done between bond of sealer to dentin between GP/AH Plus sealer and Resilon Epiphany.[15] Contradicting this finding, the results of our study correspond to a study was done using fluid filtration method comparing the sealing ability of Resilon/Epiphany and GP/AH Plus sealer, results showed significantly less leakage in Resilon/Epiphany.[21] Sealer contains a resin that is polymer, therefore polymerization shrinkage is of concern. Polymerization shrinkage disrupts the close initial contact between the sealer and the surrounding dentin and creates shrinkage gaps. These shrinkage stresses are overcome swelling of the hydrophilic resin.[13]

Endosequence BC Sealer is a recently introduced Calcium Silicate based BC sealer, described by its manufacturer as an insoluble, radiopaque, aluminum-free material that requires the presence of water to set and harden.[6,16] BC sealer being biocompatible and hydrophilic in nature it expands on setting forming a ‘self seal’, this expansion can reach upto 0.2% on completion of setting reaction.[5] This expansion, chemical and micromechanical bonding all in total increase the bonding of the sealer to root canal walls. Adding to this, high pH (12.8) during the initial 24 hours of the setting process makes this sealer strongly antibacterial.[6]

The result of our study correspond to study.[18] done using India ink dye, this study compared the apical leakage between canals filled with gutta-percha/AH-Plus and the Resilon/Epiphany System, when submitted to two filling techniques. Authors here used clearing technique and found Resilon Epiphany system to be superior. The author attributed this result to the formation of hybrid layer on root canal dentin wall.

The overall lowest mean values for Group A (Endosequence BC Sealer) may be attributed to aforementioned, near to ideal sealer properties and some drawbacks of sealer used in Group B and C. These results are supported by studies done comparing bond strength.[16] and bond strength in presence of moisture.[19] but in an SEM study.[20] done using fluid filtration method that compared BC sealer with resin sealer using two different obturating techniques; SEM analysis of the samples showed gaps at sealer-dentine and the cone-sealer interfaces for specimens that leaked the most, it was concluded that iRootSP was equivalent to AH Plus sealer.

CONCLUSION

Leakage cannot be totally eliminated from the fate of a root canal treated teeth; lateral canals, accessory canals and other anatomical variation play an important role in this, with periapical pressure being the leading factor. Considering that the areas which are commonly unaffected by instrumentation and irrigation during root canal preparation, where an more viscous material like sealer can’t reach, can open up spaces for leakage and decrease the chances of success.