Written by Garrett M. Guess, DDS Sunday, 30 November 2008 19:00
Obturation of the cleaned and shaped root canal space has been performed for many years using a core of gutta-percha rubber cones combined with various formulations of sealer cements. This step in root canal treatment is an effort to create a root canal system that is sealed from reinfection resulting from coronal leakage, and to entomb residual bacteria and their by-products remaining in the roots following cleaning and shaping procedures. The gutta-percha cones can be manipulated into the root canal with either cold lateral condensation, or through a method which involves softening the core filling material with the application of heat, which was introduced more than 40 years ago by Dr. Schilder.1 The gutta-percha and sealer filling material has been the most popular and most tested filling material throughout the history of nonsurgical endodontic procedures.
THERMOPLASTIC FILLING MATERIALS INTRODUCED
Despite significant advances in materials science over the past 50 years, it was just recently that an alternative filling material for root canal obturation was introduced and studied in an attempt to improve upon the successful history of gutta-percha. A new a polycaprolactone resin-based thermoplastic filling material (Resilon [Resilon Research LLC]) has been introduced that differs from gutta-percha—the rubber in the gutta-percha material has been replaced with a urethane-based resin. A dual-cured methacrylate resin sealer cement (Epiphany [Pentron Clinical Technologies]) was developed to be utilized with a self-etching primer in association with Resilon in an attempt to create a root filling material that is of a single, solid, bonded material. This system differs from the gutta-percha sealer-based obturation material because it has the ability, through dentin adhesive resin-bonding technology, to bond the root canal walls to the sealer cement, which in turn bonds to the core filling material. This has the potential to strengthen roots and to improve the leakage resistance of the obturated root, hopefully improving nonsurgical endodontic outcome success over the long term. The Resilon and Epiphany obturation material is available under different names: Resilon/Epiphany (Pentron Clinical Technologies), Resinate (Obtura Spartan), and RealSeal (SybronEndo).
In the past 4 years, sponsored and independent research has been busy determining if the new Resilon material is an acceptable alternative to the time-tested gutta-percha and sealer. Factors that have been tested include the cement’s cellular toxicity, bacterial leakage in filled roots, fluid filtration leakage comparisons, microscopic bonding visual analyses, bond strength to root dentin studies, periapical inflammation evaluations, and clinical outcome comparisons. Based on the majority of the current research through 2008 covering the various aspects of the new material, studies show that the new filling material is a viable alternative to the gutta-percha-sealer technique for filling roots in nonsurgical endodontic treatment. Furthermore, future research and development may eventually reveal that it has the potential to be a better material than gutta-percha.
NEW MATERIAL CHALLENGES: HANDLING
Despite significant amounts of published research, there is little information about the handling difference between this new root-filling material compared to its traditional alternative. While the dispensing of the Resilon/Epiphany system comes in similar standardized (ISO) cone forms, or pellet form for use in heated syringable dispensing systems (ie, Obtura II [Obtura Spartan] or the Hot Shot [Discus Dental]); the newer material handles differently in several ways. The Resilon core-filling material has less body stiffness and cohesion when compared to a standard gutta-percha cone. This translates into a cone that is softer (less stiff) and can be pulled apart easier. For example, if a master cone does not match the instrumentation size precisely, a cone that fits 0.5 mm short of the desired length cannot be “pushed” that extra distance with pressure on the cone itself. This is because the softer cone will buckle under pressure and will not slide apically like a gutta-percha cone might have a tendency to do. Additionally, if a Resilon cone is placed into a canal where it has very firm “tug-back,” if the cone is pulled on to withdraw it, there is a risk that the cone can be pulled apart upon withdrawal leaving the firm-fitting apical fragment in place. Of course, the flipside of this situation is that less tugback is required to successfully perform various obturation procedures. For example, when using a single master cone warm vertical obturation technique and there is inadequate tug-back present, the master cone could be withdrawn attached to the heated plugger. This is more difficult to do with a softer Resilon cone. Although the cone feels different in this subtle way, its flow characteristics and adaptability to the root canal walls have been studied and found to perform comparably to heated gutta-percha with sealer techniques in replicating anatomic depressions and filling lateral canals.2-4 In lateral condensation filling techniques, the softer cone does lead to an increased spreader-depth penetration versus gutta-percha cones.5 As a result, this permits further spreader penetration, which is essential for better master cone adaptation.6
Figure 1. Tooth No. 18 is obturated with Resinate (A brand of Resilon [Obtura Spartan]) obturation material. Note the greater radiopacity of this filling material compared to the gutta-percha filling in tooth No. 19.
Figures 2a and 2b. Tooth No. 18 obturation with a thermoplastic root filling material (Resinate). Note the void in the mesiobuccal canal found on the post-obturation x-ray that required reaccessing and refilling to correct the void.
The Resilon material seems to be “stickier” as well. When a large amount of the warmed material is injected into the root canal, if a condensation plugger (Figure 3) is inserted in deeply to vertically condense the material into the root canal, the Resilon material will have a tendency to stick to the plugger. As a result, it can be completely or partially withdrawn instead of remaining in the canal space. Once again, this problem can be avoided by injecting multiple smaller backfilling increments that do not require deep condenser penetration.
Greater filling material radio-pacity also means that overfilling becomes more apparent. While it takes large amounts of ZOE sealer extruded beyond the root apex to visualize the overfilling on a radiograph, it takes very little extruded Epiphany sealer to be visible on radiographs. Pumping a master cone to distribute the Epiphany cement in a patent root canal will frequently result in significant sealer extrusion; and while studies show that extruded Epiphany and Resilon is biocompatible and tolerated as well as other gutta-percha-sealer type root filling materials9, keeping the root filling confined to the spaces of the root canal is an objective of nonsurgical endodontic therapy. Therefore, the technique of pumping master cones or precoating the canal with sealer is not recommended.
Since the Resilon-Epiphany root filling material is a composite resin-based system, it will not pose a deleterious effect upon the subsequent resin-bonding procedures often used for coronal restorations. On the other hand, it has been shown that these bonding procedures can be affected by eugenol-containing root fillings, especially eugenol-containing sealers.10,11 The Resilon root filling can be light-cured to a coronal depth of 2 mm (according to the manufacturer). However, due to the unfavorable root canal C-factor and inherent polymerization shrinkage that is exacerbated when curing rapidly with a light, this is not a required step.12 The Resilon/Epiphany self-curing time is approximately 30 minutes in the deep areas that are unreachable by light curing.5
|Figure 3. S-Kondensors (Obtura Spartan).|
|Figure 4. An example of one of the thermoplastic filling material kits and heated syringable dispensing systems available (Resinate Kit and Obtura III Max Unit and HP [Obtura Spartan]).|
It is well known that when a gutta-percha and sealer is in contact with saliva in the oral cavity, complete reinfection of the root canal can occur in a short amount of time.19 This is an indication that the current popular choice of root filling materials does not always perform as expected, and a newer filling material is needed that can perform with even better results.
In the past 4 years, Resilon, and its other brand names Resinate (Figure 4) and RealSeal, have been shown to be an effective alternative to gutta-percha for filling the roots of endodontically treated teeth. With further studies, research, and development, this material may evolve to eventually retire gutta-percha as the endodontic root filling of choice.
- Schilder H. Filling root canals in three dimensions. Dent Clin North Am. Nov 1967:723-744.
- Versiani MA, Carvalho-Junior JR, Padilha MI, et al. A comparative study of physicochemical properties of AH Plus and Epiphany root canal sealants. Int Endod J. 2006;39:464-471.
- Alicia Karr N, Baumgartner JC, Marshall JG. A comparison of gutta-percha and Resilon in the obturation of lateral grooves and depressions. J Endod. 2007;33:749-752.
- Karabucak B, Kim A, Chen V, et al. The comparison of gutta-percha and Resilon penetration into lateral canals with different thermoplastic delivery systems. J Endod. 2008;34:847-849.
- Nielsen BA, Beeler WJ, Vy C, et al. Setting times of Resilon and other sealers in aerobic and anaerobic environments. J Endod. 2006;32:130-132.
- Allison DA, Weber CR, Walton RE. The influence of the method of canal preparation on the quality of apical and coronal obturation. J Endod. 1979;5:298-304.
- Tanomaru-Filho M, Jorge EG, Guerreiro Tanomaru JM, et al. Radiopacity evaluation of new root canal filling materials
by digitalization of images. J Endod. 2007;33:249-251.
- Rasimick BJ, Shah RP, Musikant BL, et al. Radiopacity of endodontic materials on film and a digital sensor. J Endod. 2007;33:1098-1101.
- Sousa CJ, Montes CR, Pascon EA, et al. Comparison of the intraosseous biocompatibility of AH Plus, EndoREZ, and Epiphany root canal sealers. J Endod. 2006;32:656-662.
- Ngoh EC, Pashley DH, Loushine RJ, et al. Effects of eugenol on resin bond strengths to root canal dentin. J Endod. 2001;27:411-414.
- Macchi RL, Capurro MA, Herrera CL, et al. Influence of endodontic materials on the bonding of composite resin to dentin. Endod Dent Traumatol. 1992;8:26-29.
- Nagas E, Cehreli ZC, Durmaz V, et al. Regional push-out bond strength and coronal microleakage of Resilon after different light-curing methods. J Endod. 2007;33:1464-1468.
- Schwartz RS. Adhesive dentistry and endodontics. Part 2: bonding in the root canal system-the promise and the problems: a review. J Endod. 2006;32:1125-1134.
- Tay FR, Pashley DH. Monoblocks in root canals: a hypothetical or a tangible goal. J Endod. 2007;33:391-398.
- Wang CS, Debelian GJ, Teixeira FB. Effect of intracanal medicament on the sealing ability of root canals filled with Resilon. J Endod. 2006;32:532-536.
- Cotton TP, Schindler WG, Schwartz SA, et al. A retrospective study comparing clinical outcomes after obturation with Resilon/Epiphany or Gutta-Percha/Kerr sealer. J Endod. 2008;34:789-797.
- Conner DA, Caplan DJ, Teixeira FB, et al. Clinical outcome of teeth treated endodontically with a nonstandardized protocol and root filled with resilon. J Endod. 2007;33:1290-1292.
- Leonardo MR, Barnett F, Debelian GJ, et al. Root canal adhesive filling in dogs’ teeth with or without coronal restoration: a histopathological evaluation. J Endod. 2007;33:1299-1303.
- Torabinejad M, Ung B, Kettering JD. In vitro bacterial penetration of coronally unsealed endodontically treated teeth. J Endod. 1990;16:566-569.
Dr. Guess is a Diplomate of the American Board of Endodontics and maintains his private endodontic practice in La Jolla, California. He is an associate clinical professor at the University of Pennsylvania, in the Department of Endodontics. He is the technology editor for the San Diego County Dental Society newsletter, and has published numerous research papers in the Journal of Endodontics. He can be reached by e-mail at firstname.lastname@example.org.
Disclosure: Dr. Guess has no financial interest in any of the companies mentioned in this article.
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