Abstract
Objective:
To evaluate the apical sealing ability and adaptation of three resin-based sealers to the dentine.
Materials and Methods:
A total of 66 recently extracted human maxillary anterior teeth were subjected for the study. The teeth were prepared and obturated with gutta-percha by a lateral condensation using AH Plus, Endorez and Epiphany sealers. Fifteen teeth from each group were used for the apical leakage test and the remaining five teeth from each group were used for examination under the scanning electron microscope. Data were analyzed using one-way ANOVA and the Student Newman-Keuls test.
Results:
Epiphany sealer showed better sealing ability and adaptation to dentine.
Conclusion:
The Epiphany sealer has a better apical sealing ability and adaptation to dentine than the AH Plus and Endorez sealers.
Keywords: AH plus, apical leakage, Endorez, Epiphany, lateral condensation, resin-based sealer, scanning electron microscope
INTRODUCTION
The root canal system is the clinician's road wayto success.[1]Numerous studies have been conducted to evaluate the success and failure of endodontic treatment.[2–4]
The current concept among clinicians is that after complete debridement, a three-dimensional obturation of the root canal space that is free of inflammation constitutes the key factor for successful endodontic therapy.[5] However, it has been reported that a complete seal of the root canal system is almost impossible with the currently accepted materials and obturation techniques using a combination of gutta-percha and root canal sealer.[6]
Several materials and techniques have been advocated for filling root canals with lateral condensation of gutta-percha cones complemented with sealer cement being the most widely accepted technique.[7] Many techniques have been suggested and evaluated, most of them advocating the use of gutta-percha as the core material and with sealer of a different composition to fill the residual gaps between the individual gutta-percha points and between the gutta-percha and the canal wall.[8]
Different sealer formulations have been subjected to extensive research with respect to their mechanical and biological properties, reflecting the prevailing belief that the appropriate selection of a sealer and its clinical performance may influence, at least in part, the outcome of endodontic therapy.[9]
Ideally, the root canal sealer should be capable of producing a bond between the core material and the dentine of the root canal, effectively preventing leakage. It should also be non-toxic and, preferably, have a positive effect on the healing of periapical lesions.[8]
A great variety of endodontic sealers are available commercially and they are divided into groups according to their chemical composition. There are sealers based on zinc oxide and eugenol, epoxy resin, calcium hydroxide and glass ionomer.[10]
Endodontic sealers based on zinc oxide and eugenols have been used clinically for several decades because they have satisfactory physicochemical properties.[11] The glass ionomer sealers were introduced into root canal treatment because of their adhesion to dental hard tissues.[12]
At present, sealers based on epoxy resins afford very good physical properties and ensure adequate biological performance. Excellent apical sealing has been found with epoxy resin-based sealers.[13] Previous studies showed that the epoxy resin-based root canal sealer, AH Plus, is cytocompatible,[14] biocompatible and has good tissue tolerance,[15] long-term dimensional stability[16] and good sealing ability.[17]
Recently, Endorez, a new resin-based sealer, has been introduced and its active ingredient is urethane dimethacrylate (UDMA). The UDMA is a monomer forming the organic matrix of composite resins. Materials including resin adhere adequately to the dentine. According to the manufacturer, Endorez is biocompatible and has satisfactory sealing properties, hydrophilic characteristics and early delivery system.[18]
Epiphany is a new material that was developed to replace gutta-percha and traditional sealers for root canal obturation. The Epiphany sealer is a dual curable dental resin composite sealer.[19]
The purpose of this in vitro study was to compare the apical sealing ability and adaptation of three resin-based sealers to dentine.
MATERIALS AND METHODS
A total of 66 recently extracted intact, non-carious, non-restored human maxillary anterior teeth that were free from malformed roots, calcified root canals, open apices and had straight roots were subjected for the study. All 66 teeth were cleaned to remove surface calculus and stains. The teeth were placed in 5.25% NaOCl (Vensons, Bangalore, India) solution for 8 h to remove the surface soft tissues and debris, then washed with tap water and, subsequently, stored in saline solution until they were used.
The crowns of the teeth were sectioned at the cemento-enamel junction using a water-cooled diamond disc. Routine access openings were prepared and then the working lengths were visually determined by subtracting 1 mm from the length of a size 10 K-file (Dentsply, OK, USA) at the apical foramen. All the canals were instrumented to the working length with a size 50 K-file (Dentsply) using the step-back technique. The middle and coronal thirds were prepared using size 2–4 Gates Glidden drills (Mani Inc., Tochigi, Japan) with a low-speed hand piece. The root canals were irrigated with 1 ml of 5.25% NaOCl (Vensons) after each file while instrumenting the canals. The patency of the apical foramen were confirmed with a size 10–15 K-files (Dentsply). Following the root canal preparation, in order to remove the smear layer, the canals were irrigated with 10 ml of 17% ethylenediaminetetraacetic acid (EDTA) (Septodont, Cedex, France) for 1 min and 10 ml of 5.25% NaOCl (Vensons).[18] A syringe with a 23-gauge needle was used for irrigation. Finally, the root canals were flushed with 3 ml of distilled water and then dried with paper points.
The teeth were randomly divided into three groups of 20 teeth each and the remaining six teeth served as a dye leakage control.
Group 1: Gutta-percha with AH Plus sealer.
Group 2: Gutta-percha with Endorez sealer.
Group 3: Gutta-percha with Epiphany sealer.
Control groups
Group 4: Positive control of gutta-percha with AH Plus sealer.
Group 5: Positive control of gutta-percha with Endorez sealer.
Group 6: Positive control of gutta-percha with Epiphany sealer.
Group 7: Negative control of gutta-percha with AH Plus sealer.
Group 8: Negative control of gutta-percha with Endorez sealer.
Group 9: Negative control of gutta-percha with Epiphany sealer.
Each sealer was prepared according to the manufacturer's instructions and the canal walls were slightly coated with a sealer using a size 45 K-file (Dentsply) with a counter-clockwise motion.[18] The apical part of the master gutta-percha cone was coated with the mixed sealer and placed in the canal. The canals were filled with accessory cones by the lateral condensation technique.
The access openings were closed with Cavit and all specimens were kept in 100% humidity at 37°C for 72 h to allow the sealers to set.
Fifteen teeth from each group were used for the apical leakage test and five teeth were reserved for examination with a scanning electron microscope (SEM). Three teeth, which served as negative controls, were filled with sealers and gutta-percha points. Three teeth, which served as positive controls, were left unfilled.
Apical leakage test
Apical leakage was estimated by a dye penetration test. The root surfaces of all specimens were coated with two layers of nail varnish and sticky wax with the exception of the apical 1 mm, but the root surfaces of the negative control teeth were entirely coated with two layers of nail varnish and sticky wax to prevent possible leakage.
The specimens were then immersed in 2% methylene blue solution for 7 days at 37°C. After being removed from the dye solution, the specimens were washed with tap water and dried and then the nail varnish and sticky wax were removed with a scalpel. The root of each tooth was grooved longitudinally in the bucco-lingual direction using a low-speed diamond disc under constant cooling with distilled water, without disturbing the gutta-percha filling and then the root was longitudinally sectioned.
Maximum dye penetration was measured in millimeters in each half of each tooth from the apex to the most coronal part of the root canal to which the dye had penetrated using a stereomicroscope.
Scanning electron microscope examination
Reserved five specimens from each group were prepared for SEM examination. The roots were grooved longitudinally as it was mentioned above. They were then split into two halves by placing a cement spatula in the grooves and applying gentle pressure. Both fractured halves of each root were mounted on aluminum stubs, vacuum-dried, coated with 20 nm of gold and then examined under SEM. The penetration of sealers into dentinal tubules and adaptation to dentinal walls were examined from the apical to the coronal and microphotographs were taken at 1500× magnification.
The results were statistically analyzed using one-way ANOVA and the multiple comparisons among the groups was carried out by the Student Newman-Keuls test. The level of significance was fixed at P <0.05.
RESULTS
Analysis of results
Apical leakage test
The positive control teeth showed complete leakage throughout the length of the root canal, whereas the negative control teeth revealed no dye penetration. Dye penetration in the experimental groups occurred mainly at the interface of the sealer and the root canal wall in the majority of the specimens.
Table 1 shows the mean microleakage (mm), SD and SE for each study groups.
Table 1.
Mean microleakage, SD and SE in the study groups
The mean value of dye penetration for the AH Plus root canal sealer was 6.9 ± 0.62 mm, Endorez sealer was 9.36 ± 0.86 mm and Epiphany sealer was 3.85 ± 0.89 mm.
Table 2 shows the multiple comparison of mean leakage and SD of each study groups.
Table 2.
Multiple comparisons among the three groups
Multiple paired comparisons (Student Newman-Keuls Test) showed that group 3 (GP and Epiphany) had the least amount of microleakage than all the other groups; group 1 (GP and AH Plus) proved to have the second-least amount of microleakage among the groups. Group 2 (GP and Endorez) demonstrated the greatest amount of microleakage. There was a significant difference between group 3 (GP and Epiphany) and group 2 (GP and AH Plus) (P < 0.05).
Scanning electron microscope examination
The SEM study was carried out for dentine adaptability. SEM examination showed better dentine adaptability for group 3 (GP and Epiphany) than group 1 (GP and AH Plus) and group 2 (GP and Endorez).
(Please refer for the Table 1 and Table 2 and Figure 1)
Figure 1.
Comparison of microleakage among three sealers
Discussion
Ideally, the root canal sealer should be capable of producing a bond between the cone material and the root dentine effectively preventing leakage.[8] Three-dimensional sealing of the root canal is one of the main goals of endodontic treatment and is essential for preventing reinfection of the canal and for preserving the health of the periapical tissues, thereby ensuring the success of root canal treatment. Thus, several types of endodontic sealers have been recommended to achieve this goal and, consequently, the evaluation of the apical sealing ability of the sealers is important. It is important to point out that not only is the apical seal of the root canal but the coronal seal is of equal importance for the success of endodontic treatment.[10] In this study, apical sealing and adaptation of three resin-based sealers to dentine was assessed.
Many techniques have been suggested and evaluated, most of them advocating the use of gutta-percha as the core material and with sealers of a different composition to fill the residual gaps between the individual gutta-percha points and between the gutta-percha and the canal wall.[8] Different sealer formulations have been subjected to extensive research with respect to their mechanical and biological properties, reflecting the prevailing belief that the appropriate selection of a sealer and its clinical performance may influence, at least in part, the outcome of endodontic therapy.[9]
Ideally, further directions should focus on materials that penetrate the patent dentinal tubules, bind intimately to both organic and inorganic phases of dentin, neutralize or destroy microorganisms and their products, predictably induce a cemental regenerative response and strengthen the root system.
Resin-filling materials have steadily gained popularity and are now accepted as a root canal filling materials (ADA Council on Scientific Affairs 1998). AH Plus is a two-component paste root canal sealer, based on polymerization reaction of epoxy resin-amines.[20] Recently, a new methacrylate-based endodontic sealer, Endorez, was introduced as root canal sealer.[21] Epiphany sealer is a dual curable dental resin composite sealer. The resin matrix is a mixture of BisGMA, ethoxylated methacrylates, urethane dimethacrylate resin and hydrophilic difunctional methacrylates.[22]
Leakage studies on the sealing properties of endodontic materials are still important and relevant.[17] Different methods have been used to evaluate the sealing of endodontic cements. Assessment of linear dye penetration is a common method used to explore apical leakage of root fillings after splitting the roots. The leakage marker used in this study was methylene blue because it has a low molecular weight and penetrates more deeply along the root-canal filling.[23] It is well known that root-filling materials penetrate better into dentinal tubules in the absence of the smear layer.[24] In this study, 17% EDTA and 5.25% NaOCl were used as irrigation solution to remove the smear layer.[18]
Results of this study showed that group 3 (GP and Epiphany) showed less microleakage than group 1 (GP and AH Plus) and group 2 (GP and Endorez). There was a statistically significant difference when the three groups were compared. Group 1 (GP and AH Plus) showed less microleakage than group 2 (GP and Endorez).
These results are in agreement with the following studies.
A recent study compared the apical sealing ability of the new resin-based Epiphany-Resilon root canal filling system with the sealing abilities of different pairings of AH Plus, gutta-percha, Epiphany and Resilon. This study showed that the Epiphany gutta-percha combination had a lower amount of microleakage than the AH Plus gutta-percha combination.[25]
A study evaluated the setting time, solubility and disintegration, flow, film thickness and dimensional change following setting in a dual-cured resin root canal sealer Epiphany compared with an epoxy-resin-based sealer AH Plus. This study showed that the setting time, flow and film thickness tests for both cements conformed to ANSI/ADA standards. The dimensional alteration test for both cements was greater than the values considered acceptable by ANSI/ADA. Epiphany values regarding solubility were also greater than values considered acceptable by ANSI/ADA.[26]
A study assessed the bond strength of the new resin-based Epiphany-Resilon root canal filling system and compared this with bond strengths of different pairings of AH Plus, gutta-percha, Epiphany and Resilon. The Epiphany gutta-percha combination showed significantly (P < 0.001) greater bonding strength than all the other groups.[27]
An in vitro study was conducted to evaluate the apical leakage of three root-canal sealers: AH Plus, Diaket and Endorez, using a new computerized fluid filtration meter. This study showed that the root fillings with Diaket in combination with the cold lateral condensation technique showed lower apical leakage than AH Plus and Endorez.[28]
The scanning electron microscopy showed that Epiphany had adapted better to dentine and penetrated more into dentinal tubules than the AH Plus and Endorez root canal sealers from apical to coronal of root canal. All the sealers showed poorer adaptation and penetration in the apical third than the coronal and middle thirds of the root canal. This difference may be due to the removal efficiency of the smear layer in the apical third of the canal. In addition, the number and size of the dentinal tubules and the structure of the dentine (tubule density) in the apical third and the employed obturation techniques may affect the adaptation and penetration of sealers.
The probable reason for less microleakage for the combination of gutta-percha and Epiphany sealer are:
The configuration factor (C-factor), defined as the ratio of bonded to unbonded surface areas of cavities, in a root canal is highly unfavorable and contributes to maximizing the polymerization stress of resin-based materials along the root canal walls. There is extremely high C-factor encountered in long, narrow root canals, tending to cause a resistance in the relieving of shrinkage stresses during polymerization. Focusing on this issue becomes more critical as the resin sealer is light cured to create an immediate coronal seal. Because this prevents stress relief by resin flow and the resin sealer may detach from dentin walls thus creating interfacial gaps. However, despite these problems, the results for the present study indicated that the Epiphany sealer and the gutta-percha core combination had the least amount of microleakage than all the other groups. One possible explanation is that the gutta-percha is more compactable than Resilon and thus may partially compensate for interfacial stresses by lateral compaction and also helps to resist dislodgement.[25]
Self-etching primer was used with Epiphany sealer in this study. This might probably have increased the penetration of Epiphany sealer into the root canal dentine. Therefore, this increased the adaptability of sealer to root canal dentine, thereby decreasing the apical leakage.[26]
Conclusion
According to results of this study, the dual curable methacrylated resin with a self-etching primer Epiphany had better apical sealing ability and better adaptability to dentine than epoxy-based AH Plus sealer and methacrylate-based Endorez sealer. But, further studies using different sealers and techniques are warranted before Epiphany can be recommended for clinical application.
Footnotes
Source of Support: Nil
Conflict of Interest: None declared
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