January 2006
featured on page
76
Kenneth Koch, DMD, and Dennis G. Brave, DDS
Endodontics has been witness to many obturation techniques, and there are clinicians who can obtain excellent results with any of these methods. However, there are two goals of obturation that have not been addressed with these methods. The first is to create a hermetic seal within the root canal system. The second is to establish a technique that gives the greatest majority of clinicians the ability to produce superior results. It is with these goals in mind that the Activ GP™ Obturation System was developed. This technique uses improved glass ionomer technology and combines it with advanced material science to result in a technique that provides both hermetic seal and superior results.
In the pursuit of a true single-cone technique, glass ionomer is attractive because of its superior biocompatibility and physical properties. The merits of glass ionomer are numerous. First, in addition to having the capability of wet bonding (ie, it does well in a moist environment), glass ionomer actually creates an ionic bond to the dentin. This bond is critical in terms of a monobloc (hermetic seal). Secondly, glass ionomers are nonresorbable, which is critical in a single-cone or sealer-based obturation technique. Because of the great biocompatibility of glass ionomer, the fact that it does not undergo resorption is not a problem. In fact, glass ionomer cements have been used routinely in orthopedic surgery to hold fixtures or fragments in place. Furthermore, the setting time of glass ionomer is such that the clinician can prepare a post and place it at the same appointment as the endodontic procedure.
Although the merits and properties of glass ionomer were well known, there remained some limitations with the first-generation glass ionomer sealers. The handling characteristics of these sealers were a challenge and they generally did not produce a sufficient working time. Furthermore, they did not demonstrate a bond to gutta-percha. Consequently, altering the properties of glass ionomer sealer to meet the requirements of a monobloc was the first challenge.
The first change made was with the working time. By modifying the particle sizes of the glass ionomer, the working time has been extended. The working time of Activ GP sealer is 12 minutes on a paper pad and 20 minutes on a chilled glass slab. Furthermore, Activ GP sealer comes in a powder/liquid combination that allows the assistant to mix it to a consistency that is favorable for the clinician and the individual case.
Although changes were made with the sealer, the lack of a bond between the sealer and the gutta-percha still remained a challenge. This challenge was met by taking silanated glass ionomer particles (present in the sealer) and placing them into the gutta-percha cones at a percentage that does not affect the properties of gutta-percha. Additionally, the impregnated cones were coated with glass ionomer particles at a thickness of 2 µm. Scanning electron microscopy shows that there is no gap between the coating of glass ionomer and the glass ionomer-impregnated gutta-percha cones (Figure 1A View Figure and Figure 1B View Figure).
As a result of these enhancements, Activ GP sealer now has the ability to bond directly to the Activ GP points. The result is a monobloc between the canal wall, the Activ GP sealer, and the master cone. This allows the creation of a true hermetic seal, which is a very significant development in endodontics (Figure 2 View Figure and Figure 3 View Figure).
The Activ GP System (Figure 4 View Figure) is ISO sized and colored and is available in two types: a traditional design and an enhanced version (Activ GP Plus). Activ GP Plus uses calibration rings for easy depth measurement and a unique barrel handle which, when placed with an insertion instrument (transporter), facilitates easy placement into the canal (Figure 5A View Figure and Figure 5B View Figure).
This Activ GP Obturation System delivers a true monobloc obturation result through a single-cone technique. However, the system still remains precision-based, which means it requires synchronicity between the file and the master cone. The sizes of Activ GP points are consistently accurate and are verified as such by laser measurement. In fact, all Activ GP points are laser verified to match the preparations made by the 0.04 or 0.06 tapered EndoSequence file system. The precision matching of the primary cone to the preparation is very important with a single-cone technique because the accuracy of the cones to the preparation minimizes the amount of sealer and any potential shrinkage.
The technique associated with Activ GP is straightforward. After completion of a constant taper preparation and verification by radiograph of the fit of the Activ GP cone, a hand file is chosen that matches the final size of the preparation. The file is coated with the Activ GP sealer and taken to working length. It is recommended that this process is repeated a second time.
After placement of the sealer, the Activ GP cone is coated with sealer and slowly inserted into the canal to its working length. As a result of the endodontic synchronicity between the file and master cone, hydraulics is generated, which moves the sealer into lateral canals. However, because it is inserted slowly, any excess sealer will extrude out coronally alongside the cone (Figure 6 View Figure).
After the cone has been inserted to working length and verified with a digital image or radiograph, it is recommended that the cone be seared off at the orifice and that an additional 1 mm to 2 mm of gutta-percha be removed from the canal. After removal of the gutta-percha, the Activ GP sealer is placed on top of the cone to act as a final canal cap. This procedure will effectively prevent coronal leakage, which can contaminate the completed root canal.
The Activ GP obturation technique meets two significant criteria. First is the introduction of improved glass ionomer technology that can result in a true monobloc obturation, which allows the creation of a hermetic seal within the root canal. Second, a simple, sophisticated technique has been introduced, which gives the greatest majority of practitioners the ability to produce superior obturation results. The patient is the true beneficiary of this technology (Figure 7 View Figure, Figure 8 View Figure, and Figure 9 View Figure).
For more information, contact:
Brasseler USA
Phone: 800-841-4522
E-mail: info@brasselerusa.com
Web: www.brasselerusa.com