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Basic Research—Technology

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ush-Out Bond Strength of a New Endodontic Obturationystem (Resilon/Epiphany)arilia M. Sly, DDS, MSD, B. Keith Moore, PhD, Jeffrey A. Platt, DDS, MS, andecil E. Brown, DDS, MS

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bstractndodontic sealers should demonstrate adhesiveroperties to dentin to reach the objectives of thebturation of the canal space and seal the canalpace both apically and coronally, thus decreasinghe chance of endodontic treatment failure. Adhe-ion to dentin with bonding to the tooth structure inhe canal may provide greater resistance to toothracture and greater clinical longevity of an endodon-ically treated tooth. In this study, human single-anal canines were endodontically treated and ob-urated with two different endodontic obturationystems (Epiphany/Resilon system and gutta-per-ha/AH 26). Thirty roots (divided into two groups)ere horizontally sliced for a push-out strength test,hich was performed from apical to coronal in theniversal testing machine. Differences in push-outond strength between the two different materialystems were obtained using repeated measuresnalysis of variance on ranks. Gutta-percha had sig-ificantly higher push-out bond strength than Epiph-ny (p � 0.0001). (J Endod 2007;33:160 –162)

ey WordsH 26, bond strength, gutta-percha, push-out test,esilon

From the Indiana University School of Dentistry, Dentalaterials, Indianapolis, Indiana.

Address requests for reprints to Dr. Marilia Mattos Sly,ndiana University School of Dentistry, Dental Materials, 1121

est Michigan St., Room 118, Indianapolis, IN 46202. E-mailddress: msly@iupui.edu.099-2399/$0 - see front matter

Copyright © 2007 by the American Association ofndodontists.oi:10.1016/j.joen.2006.09.014

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60 Sly et al.

utta-percha is the most commonly used core filling material for endodontic obtu-ration. Although it is not the ideal filling material, it has been used in conjunction

ith a sealer as the material of choice for over 100 years.The objectives of the canal space obturation are to prevent leakage from the oral

avity and the periradicular tissues into the root canal system and to seal any microor-anisms that could not be entirely removed during cleaning and shaping procedures1). In addition, sealers should demonstrate adhesive properties to dentin, decreasinghe chance of endodontic treatment failure. Increased adhesive properties to dentin

ay lead to greater strength of the restored tooth, which may provide greater resistanceo tooth fracture and clinical longevity of an endodontically treated tooth.

The Epiphany/Resilon obturation system is a new thermoplastic synthetic polymer-ased root canal filling material. The manufacturer claims that it performs, handles, and

ooks like gutta-percha. They also claim that it forms a monoblock that bonds to theentinal walls when the Epiphany points are used in conjunction with the Epiphanyual-cured resin sealer (Resilon) and the Epiphany primer (2–5).

The purpose of this in vitro study is to evaluate the push-out bond strength tontraradicular dentin of two polymeric endodontic obturation systems, Epiphany/Resi-on and gutta-percha/AH 26. The null hypothesis tested was that there is no differencen the push-out bond strength between the two types of obturation systems.

Materials and MethodsAn in vitro study was conducted using 30 extracted human canines. The crown

ortion of each tooth was removed by means of a water-cooled saw (Gillings Hamcohin Sectioning Machine, Hamco Machines, Inc., Rochester, NY). Working length ofach tooth was determined by a K-file #10, until it reached the apical foramen, sub-racting 1 mm from this measurement. The teeth were endodontically treated accordingo a crown-down Profile Series 29 technique. The irrigation solutions used for cleaningnd shaping procedures were 5.25% sodium hypochlorite and RC Prep (Premier Den-al Products, Tulsa, OK). After the cleaning and shaping processes, 17% ethylenedia-

inetetraacetic acid (EDTA) for 1 minute was used followed by sterile water as a finalinse. Paper points were used to dry the canals before obturation.

The 30 teeth were randomly divided into two groups of 15 specimens each. Forach group, a different obturation system was used. The tested materials were (forroup EP) Epiphany Soft Resin Endodontic Obturation System (Pentron Clinical Tech-ologies, LLC, Wallington, CT) and (for group GP) gutta-percha points (Dentsplyaillefer NA, Tulsa, OK) and AH26 Root Canal Sealing (Dentsply Maillefer NA). The

bturation systems were used with the System B Heat Source (Analytic Technology, Saniego, CA) and the Obtura II system (Obtura/Spartan, Fenton, MI) and were handledccording to the manufacturers’ instructions. Although the Epiphany sealer is a dual-ured resin system, the coronal aspect of the tooth was not light activated because onlyhe most coronal section would likely be influenced by light activation.

After the canal obturation, the teeth were radiographed to make sure the canalsere fully obturated. The 15 roots from each group were embedded in epoxy resin and

liced for the push-out bond strength evaluation in a universal testing machine (MTSintech ReNew 1123, Eden Prairie, MN).

Before testing, each root was horizontally sectioned into approximately 2-mm-hick slices from the cement-enamel junction with a water-cooled precision saw

Isomet 1000 Precision Saw, Buehler, Lake Bluff, IL). The slices were kept moist in

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Basic Research—Technology

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ontainers and the order of the slices (from coronal to apical) as well asach slice’s apical side was identified. Each slice was positioned in aeflected light microscope (Neophot 21 Metallograph, Leco Corp., St.oseph, MI), where the perimeter and diameter of each obturation siteere measured and pictures of both sides of each slice were taken withdigital camera (Digital Microscope Camera DMC 1, Polaroid,

altham, MA). On the coronal side of the slices, the larger diameter waseasured to select a support jig with a large enough hole to provide

learance for the obturating material when it was dislodged from theooth slice. On the apical side of the slices, the smallest diameter was

easured to select a punch to be used to supply load with that side,aking sure that the punch would not contact the dentin around the

bturating material, causing a crack and erroneous results. The thick-ess of each slice was measured by means of a digital caliper; thiseasurement and the perimeter measurements were used by the com-

uter in the push-out test to calculate the bonded area.Each specimen was attached to a support jig with clearance for the

islodged material on the base of the Universal Testing Machine (MTSintech ReNew 1123) with the coronal end facing the support jig and thepical end facing the load cell for the punch affixed to the crosshead toontact the apical part of the specimen. The punch moved downward atcrosshead speed of 0.5 mm per minute until extrusion of the obtura-

ion from the specimen was manifested, which usually resulted in anbrupt decrease in the applied load. Figure 1 illustrates the test meth-dology used in this study. The punch was positioned so that it onlyontacted the specimen’s obturation site, generating shear stresses onhe areas to be debonded. The computer and software connected to theniversal testing machine calculated the push-out bond strengthalue for each specimen from the average of the two perimeterscoronal and apical) and the thickness of the specimen from theormula:

Debond stress �MPa� �Debonding force �N�

Area �mm2�

igure 1. Diagram for the push-out bond strength test.

here debonding force is the maximum force before debonding and p

OE — Volume 33, Number 2, February 2007

rea (of the bonded interface) is the average value of the perimeterimes the thickness. Differences in push-out bond strength between thewo different material systems were analyzed using repeated measuresnalysis of variance on ranks.

ResultsPush-out bond strengths in MPa were recorded. A total of 78 slices

er group (approximately 5 slices each for 15 teeth) were tested. Ac-ording to Table 1, the mean push-out bond strength ranged from 0.51�0.30) MPa for group EP and 1.70 (�0.71) for group GP.

Table 2 lists the group-by-location push-out bond strength distri-utions. Location 1 and location 6 are, respectively, the most coronalnd the most apical slices obtained. N represents the number of slices ofach location that were submitted to the push-out test. The group-by-ocation interaction was not significant (p � 0.59), so the group com-arisons were not dependent upon the location in the canal.

DiscussionThe concept of bonding resin materials to enamel was first intro-

uced by Buonocore (6) in 1955. The development of resin bonding toooth structure progressed through a number of distinct stages, com-

only referred to as generations. As a greater understanding of theature and composition of the bonding interface was developed, thetrategies applied for resin retention were modified to take advantage ofhis knowledge. Because of distinctions in composition and morphologyetween enamel and dentin, the need for wet bonding arose, and tech-iques for preparing the interface for increasingly hydrophobic mono-ers were developed. The success of this restorative dentistry concept

as resulted in the acceptance of the use of polymer-based sealers forreatment of endodontically treated teeth (7). These materials haveeen introduced as root canal sealers to obtain dentinal tubular pene-

ration, bond to the collagen matrix, and, consequently, adhesivetrength to dentin (8).

A push-out test is one measure of the effectiveness of an endodon-ic obturation technique or material. Other evaluation methodologieshould include bacterial or other leakage material, light or electronicroscopic evaluation, and resorbability. There is no evidence that any

ABLE 2. Group-by-location push-out bond strength

Group Location N Mean(MPa) SD SE Min. Max.

EP 1 15 0.29 0.21 0.05 0.01 0.762 14 0.35 0.27 0.07 0.02 0.893 15 0.51 0.55 0.14 0.02 1.674 14 0.54 0.44 0.12 0.03 1.425 12 0.75 0.55 0.16 0.07 2.026 8 0.68 0.87 0.31 0.00 2.67

GP 1 15 1.60 0.97 0.25 0.45 4.372 14 1.60 1.06 0.28 0.59 4.713 14 1.65 0.83 0.22 0.73 3.664 15 1.67 0.90 0.23 0.22 3.595 14 1.84 0.74 0.20 0.80 3.146 6 1.87 0.85 0.35 1.02 3.37

ABLE 1. Push-out bond strength

Group N Mean(MPa) SD SE Min. Max.

EP 78 0.51 0.30 0.08 0.06 1.29GP 78 1.70 0.71 0.18 0.99 3.43

-value obtained from the rank transformation (not shown) (p � 0.0001).

� 0.59.

Push-Out Bond Strength 161

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f these methodologies is the best one for measuring effectiveness of anndodontic obturation material.

The results reported in the present study are similar to resultseported in other studies (9, 10). The study by Gesi et al. (9) comparedhe interfacial strengths of Resilon/Epiphany and gutta-percha/AH Plus.t was concluded that the interfacial strength achieved with Resilon/piphany to intraradicular dentin is not superior to that of gutta-per-ha and a conventional epoxy-resin sealer. In addition, the study ofay et al. (10) evaluated the adhesive strength of Resilon to a metha-rylate-based root canal sealer. The authors found that adhesive failureas characteristic of the Resilon group, and it was concluded that themount of dimethacrylate incorporated in Resilon might not be opti-ized for effective chemical coupling to methacrylate-based sealers.

he push-out test used in the current study should result in shear failuref the bonded specimens. Comparison of the strength value for Epiph-ny to shear bond strengths reported to dentin from restorative dentalaterials studies show much lower values, which brings into question

he efficacy of the bond between Resilon and root canal dentin (11).The variation in push-out bond strength seen between groups EP

nd GP may be in part attributed to the presence of voids between theentinal walls and the endodontic obturation. Voids could have beenaused by incorporation of air during placement of primer and/orealer.

Polymerization shrinkage of the sealer might also contribute to theower bond strength value observed in group EP. The amount of shrink-ge depends on the type, size, and content of filler particles as well as theype of matrix used. The stress associated with this shrinkage may resultn separation of the resin-based sealer from the dentinal walls, and,onsequently, the bond strength value of this interface would decrease.n addition, according to the study by Tay et al. (12), as the thickness ofhe adhesive is reduced, the volumetric shrinkage is reduced, resultingn a reduction of shrinkage stress. Furthermore, the interaction of thewo geometrically related C- and S-factors predicts that bonding of ad-esive root-filling materials to root canals is highly unfavorable whenompared with indirect intracoronal restorations with a similar resinilm thickness.

According to the manufacturer of the Epiphany Soft Resin End-dontic Obturation System, this material performs, handles, and looksike gutta-percha and forms a monoblock that bonds to the dentinalalls when its three components are used in conjunction. It is alsolaimed that this monoblock is formed by the bonding of the Resilonore to the resin sealer, which attaches to the primed root dentin (2–5).s previously noted, findings of the study by Tay et al. (10) do notupport the monoblock concept, showing that the core part of thepiphany system may not yet be optimized for effective chemical cou-

ling to methacrylate-based sealers, which is the case of both the Epiph-

62 Sly et al.

ny and RealSeal sealers. Resilon is the primary component of bothealSeal and the Epiphany sealer. Because of their findings, the authorsuggest further research on the ability of the sealer and the core materialo bond together.

In the study by Teixeira et al. (3), the authors evaluated the frac-ure resistance of endodontically treated teeth filled with either gutta-ercha or Resilon. It was concluded that Resilon increased the resis-

ance to fracture. However, the results of the study by Williams et al.13) show that the cohesive strength and modulus of elasticity of gutta-ercha and Resilon are relatively low. It was concluded that the stiffnessf Resilon and gutta-percha is too low to reinforce roots after root canal

herapy.The hypothesis that there would be no difference in the push-out

ond strength between the two types of canal obturation systems has toe rejected. Gutta-percha had significantly higher push-out bondtrength than Epiphany (p � 0.0001).

Therefore, it may be concluded from the present study that theush-out bond strength of gutta-percha/AH 26 to intraradicular dentin

s higher than that of the new obturation system Resilon/Epiphany.hese results challenge some of the claims for this new endodonticbturation system.

References1. Cohen S, Burns R. Pathways of the pulp, 8th ed. St Louis, MO: Mosby, 2002.2. Shipper G, Ørstavik D, Teixeira FB, Trope M. An evaluation of microbial leakage in

roots filled with a thermoplastic synthetic polymer-based root canal filling material(Resilon). J Endod 2004;30:342–7.

3. Teixeira FB, Teixeira ECN, Thompson JY, Trope M. Fracture resistance of rootsendodontically treated with a new resin filling material. JADA 2004;135:646 –52.

4. Teixeira FB, Trope M. Gutta-percha: the end of an era? Alpha Omegan 2004;97:16–22.5. Teixeira FB, Teixeira ECN, Thompson J, Leinfelder KF, Trope M. Dentinal bonding

reaches the root canal system. J Esthet Restor Dent 2004;16:348 –54.6. Buonocore MG. A simple method of increasing the adhesion of acrylic filling mate-

rials to enamel surfaces. J Dent Res 1955;34:849 –53.7. Rueggeberg F. From vulcanite to vinyl, a history of resins in restorative dentistry.

J Prosthet Dent 2002;87:364 –79.8. Spångberg L. Instruments, materials, and devices. In: Cohen S, Burns R, eds. Path-

ways of the pulp, 8th ed. St Louis, MO: Mosby, 2002;550 –3.9. Gesi A, Raffaelli O, Goracci C, Pashley DH, Tay FR, Ferrari M. Interfacial strength of

Resilon and gutta-percha to intraradicular dentin. J Endod 2005;31:809 –13.0. Tay FR, Hiraishi N, Pashley DH, et al. Bondability of Resilon to a methacrylate-based

root canal sealer. J Endod 2006;32:133–7.1. Oliveira SSA, Pugach MK, Hilton JF, Watanabe LG, Marshall SJ, Marshall GM Jr. The

influence of the dentin smear layer on adhesion: a self-etching primer vs. a total-etchsystem. Dent Mat 2003;19:758 – 67.

2. Tay FR, Loushine RJ, Lambrechts P, Weller RN, Pashley DH. Geometric factors affect-ing dentin bonding in root canals: a theoretical modeling approach. J Endod2006;31:584 –9.

3. Williams C, Loushine RJ, Weller RN, Pashley DH, Tay FR. A comparison of cohesive

strength and stiffness of Resilon and gutta-percha. J Endod 2006;32:553–5.

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