Adhesive Endodontic Obturation
A detailed overview at the obturation materials currently in clinical use, including their advantages and disadvantages, is presented.
Gregori M. Kurtzman, DDS
Gutta-percha has been in use for many decades as an obturation material matched with various sealers, but its drawbacks have long been recognized. Coronal leakage has become a growing concern in the long-term success of endodontics. Gutta-percha cannot be bonded with any sealer and, therefore, it can provide a bacterial pathway to reinfection of the tooth’s apical region. Science and technology have advanced obturation in recent years to provide better seals with greater coronal leakage prevention.
Resilon™ (Pentron Clinical Technologies; www.pentron.com) and its accompanying resin sealer, Epiphany (SybronEndo; www.sybronendo.com) was introduced 6 years ago after extensive research based on developing an obturation material that would handle similarly to gutta-percha but would allow the cone to be bondable to the sealer, thus eliminating coronal leakage.1-5
Resilon, a polymer of polyester that is bondable to the resin sealer, is provided in cones that look like gutta-percha, yet are more flexible and do not harden or become brittle over time. The cones are available in 0.02 (ISO 15-140), 0.04 (ISO 15-60), and 0.06 taper (ISO 15-45). Also available are pellets for the Obtura gun (Obtura Spartan; www.obtura.com), Hot Shot (Discus Dental; www.discusdental.com) or similar thermoplastizer units for those wishing to use warm downpack techniques or place backfills. Resilon is also available as apical plugs placed via a removable carrier (ie, Simplifill, Discus Dental).
The cones may be used via any technique used with gutta-percha: cold, warm, single-cone, lateral condensation, vertical condensation, etc. The resin sealer, Epiphany or RealSeal™ (SybronEndo), is a hydrophilic, primer-free, dual-cure methacrylate resin, with a long working time of 40 minutes. Setting time is not accelerated with heat, so warm techniques may be employed if desired. The sealer will light-cure to a depth of 1 mm to 2 mm, so a light may be used to seal the coronal before the placement of a provisional filling. The obturation material provides a dense radiographic fill (Figure 1).
Some irrigants may hamper the setting of resin sealers, such as sodium hypochlorite and peroxides. These may be used but it is advised that the canal be flushed with saline, anesthetic, EDTA, or other appropriate irrigant as the final solution in the canal prior to resin obturation.
An alternative to the newer resin sealers is ActiV GP, a glass-ionomer sealer matched to a glass-ionomer impregnated cone (Brasseler USA, www.brasselerusa.com).6-9 The cones incorporate glass particles within the gutta-percha and an adhesive surface coat covers the cones providing a highly active surface prepared to chemically adhere to the ActiV GP glass-ionomer sealer.
The cones are available in ISO sizes 15-60 in either a 0.04 or 0.06 taper in traditional-style cones. The sealer is provided in a liquid-powder formulation that offers a 12-minute working time. Because glass-ionomer cements set exothermically, mixing the sealer on a chilled glass slab will extend the working time and make placement easier. Because heat will accelerate the setting of the sealer, this material is designed to be used in a cold technique. Heated downpack techniques are not advised.
The cones are designed to match the final file size used and are used in a single-cone cold technique or can have additional cones placed coronally to complete the obturation. No alteration to irrigation is required and sodium hypochlorite can be used as the final irrigant. After completion of instrumentation, the canal is dried with paper points and the cone is tried in to check apical fit. A radiograph can be taken with the cone to verify extension of the cone to the apical foramen before sealer application. The sealer is mixed and applied into the canal with either a paper point or a hand file smaller than the canal size to coat the walls. The sized cone is coated with additional sealer, then inserted to working length and the coronal excess of the cone is removed with a heated instrument. Both the sealer and the ActiV GP cone provide a dense radiopaque fill (Figure 2).
EndoSequence BC Sealer
A more recent addition to the obturation materials available today is the EndoSequence BC sealer (Brasseler USA), a bioceramic sealer.10-12
The sealer is supplied in a premixed syringe with intraoral tips for placement directly into the canal and is used with a cone of ActiV GP. EndoSequence BC sealer is an insoluble radiopaque bioceramic based on calcium silicates that uses the moisture present in the dentinal tubules to fully set. A byproduct of this setting process is hydroxyapatite, which bonds to the canal wall. The pH during setting is 12.8, which is strongly antibacterial. No mixing of the sealer is required and the setting time is 3 to 4 hours. The material may be used with single-cone or lateral condensation obturation techniques. As the setting reaction is moisture dependent, heat may be used during obturation without accelerating the setting reaction of the sealer.
After instrumentation, excess fluid is removed from the canals with paper points and the intraoral tip affixed to the sealer syringe is inserted no deeper then the coronal third. A small amount of sealer is expressed into the canal. A #15 or equivalent hand file is used to disperse the sealer, coating all of the canal walls. The master cone is coated with additional sealer and inserted to working length. A heat source is used to remove any excess coronal cone and chamber clean-up is facilitated by swabbing the chamber with a moist cotton pellet. The result is a dense radiographic fill of the canal system (Figure 3).
The sealer needs to be used with a master cone and should not be used alone. Re-treatment can be facilitated with hand files, rotary instruments, and ultrasonics, as is accomplished with gutta-percha and traditional sealer re-treatments.
EndoREZ® sealer (Ultradent; www.ultradent.com) is a dual-cure, methyacrylate, hydrophilic, primer-free resin sealer that is used with EndoREZ points, which are resin-coated gutta-percha cones for obturation of the canal system.13-15 The sealer is provided in an automix syringe that is dispensed into an intraoral syringe with a NaviTip attached. The NaviTip is introduced to the instrumented canals’ apex and the canal is backfilled with sealer. A previously fitted EndoREZ cone is then introduced to working length and additional cones can be used to fill the canal via lateral condensation.
The EndoREZ points are available in 0.02, 0.04, and 0.06 taper in ISO sizes 25-50. An accelerator for the sealer, EndoREZ Accelerator, may be used to accelerate the sealer setting time from 15 minutes to 5 minutes. The accelerator is used after filling the canal system with sealer and placement of the master point, a #25 or smaller point is dipped into the accelerator then placed into the canal to laterally fill the coronal half of the canal. In larger canals, additional accessory points may be placed with accelerator. It is not advised to use accelerator on the master point as this may prevent full seating of the cone to working length. Also, it is suggested that a radiograph be taken with the master point seated with sealer in the canal before placement of the accessory points with accelerator, so that adjustment of the master point can be accomplished before the sealer sets. A light may be used to set the coronal sealer before cutting off the coronal excess cones. The end result is an obturation with a dense radiopaque fill (Figure 4).
As with other methyacrylate sealers, final irrigation should not be done with sodium hypochlorite or peroxides as these may interfere with resin setting, but they may be used up until final irrigation.
Carrier-based obturation has been popular for more than 20 years. The technique uses a carrier coated in gutta-percha that is thermoplastized before inserting into a canal that has had sealer applied. The main drawbacks to this technique have been technique related. No sealer has been demonstrated to adhere to gutta-percha, and gutta-percha or sealer do not bond to the carrier. As a result, as the thermoplastized carrier is inserted into the canal, the gutta-percha can be stripped off the carrier, resulting in the carrier contacting the apical canal wall and resulting in a potential leakage point. Additionally, as there is no bond coronally, potential coronal leakage can occur between the sealer and gutta-percha and the gutta-percha and the carrier.
In an extension of the science and research on Resilon, a Resilon-based bondable carrier coated with thermoplastizable Resilon and used with a resin sealer RealSeal (SybronEndo) has been developed. The product, RealSeal 1, overcomes the identified issues with gutta-percha–based carrier obturation and provides a bond between the sealer, Resilon, and carrier or the sealer and denuded carrier should any apical stripping occur.16 The system is available in ISO sizes 20-90 with matching radiographic verifiers. The system uses a different oven to thermoplastize the Resilon-coated carrier than is used with the competitive product because the heating point is lower than gutta-percha. After radiographically checking for apical fit, the verifier is used to lightly coat the canal walls with Real Seal resin sealer before insertion of the heated carrier. As the sealer has a long working time, it is advised that the sealer be placed before heating the carrier to avoid premature cooling of the thermoplastized Resilon before it can be inserted to working length within the canal. The opacity of the carrier and sealer provides for a dense three-dimensional fill (Figure 5).
Coronal leakage has been reported as the greatest potential cause of failure in properly performed endodontic treatment through leakage of the coronal restoration permitting bacterial migration through the obturation material to the apex. Gutta-percha has long been recognized as the weak link in obturation and provides no barrier to bacterial leakage because of its inability to bond to any of the traditional sealers that have been in use. Adhesive dentistry has expanded into the realm of endodontic obturation providing better, more predictable methods to seal the canal system and prevent coronal leakage.
The use of adhesive sealers may play an important role by minimizing coronal leakage. In addition, the importance of an immediate definitive coronal seal should be emphasized after obturation of the canal system. Placement of a glass ionomer or bonded resin coronal seal over the canal orifices is important to prevent coronal leakage until the final restoration can be placed. With the current economic situation, patients are delaying placement of the final restoration on endodontically treated teeth.17-19
While different obturation techniques may be similar in results, ease of use and reproducibility of the technique are key issues. The practitioner should select the material and technique that allows them to reproducibly render endodontic care at a high level of quality for long-term results.
The author has received an honorarium from Pentron Clinical Technologies, and is a current consultant for both Pentron Clinical Technologies and SybronEndo.
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About the Author
Gregori M. Kurtzman, DDS
Silver Spring, Maryland