The implant verification jig (IVJ) plays an important role in full-arch implant reconstruction, as the use of this method during the final impression stage ensures that a final prosthesis is fabricated that fits accurately on the implants or multi-unit abutments.1 The IVJ provides a solid structure that connects the impression copings in order to preserve the inter-implant relationship in the final impression, which is particularly important for full-arch cases. With multiple adjacent implants securely connected during the final impression, the jig ensures a highly accurate master cast, a passive fit, and a decrease in potentially destructive forces that may lead to bone loss or prosthetic failure.
The IVJ provides a solid structure that connects the impression copings in order to preserve the inter-implant relationship in the final impression, which is particularly important for full-arch cases.
Significant inaccuracies can occur when making an impression for a full-arch implant restoration without the use of a jig. One cause of inaccuracies is that the impression material is susceptible to shrinkage or flexure. In the case of flexure, for example, the relative position of two adjacent implant transfer copings can move within the impression material if they are not connected. Inaccuracies can also result from stone expansion when the final stone cast is fabricated. By using the IVJ, the doctor can greatly improve the accuracy of the master cast on which the final restoration is designed.
The IVJ technique is part of the standard step-by-step protocol for the BruxZir® Full-Arch Implant Prosthesis and the Inclusive® Screw-Retained Hybrid Denture, and does not require any extra office visits. At the first visit, the doctor takes a preliminary impression with closed-tray impression copings and a stock impression tray before sending the impression to the lab. Note that open-tray impressions are also acceptable. Based on the preliminary impression, the lab fabricates a custom tray along with an IVJ that has been sectioned and numbered on a working cast (Fig. 1).
At the second visit, each section of the jig is seated onto the appropriate implant or multi-unit abutment and the guide pin is tightened (Figs. 2a–2d). The sections should not be in contact; rather, each section should have a slight gap (Fig. 3). Next, the sections are luted together with a material such as Camouflage® Flowable NanoHybrid Composite (Glidewell Direct; Irvine, Calif.). Material should flow through and completely around the gaps before being fully cured (Figs. 4a, 4b). The jig can be removed in one piece, inspected extraorally and reseated.
For the final impression, the doctor checks the fit of the custom tray, ensuring it avoids contact with the jig or cylinders (Fig. 5). The final impression is taken using a medium-body and heavy-body VPS material and open-tray technique (Figs. 6, 7). Once the material has set, the guide pins are loosened, followed by the removal of the impression. At this point, the IVJ is picked up in the impression (Fig. 8). The practitioner can inspect the impression and send it to the lab for the fabrication of the final prosthesis.
It is critical to take this second impression to ensure an accurate fit of the full-arch prosthesis. An ill-fitting restoration could result in complications, such as screw loosening, screw fracture or bone loss around the supporting implants. My patients seem to appreciate the extra care as I explain that the first impression is going to get us close, but the second impression is going to be perfect.
The IVJ method allows doctors a higher degree of accuracy in the fabrication of the final prosthetic restoration. This method of connecting the implants together leads to a more accurate master cast and the fabrication of a final prosthesis that achieves a passive fit, which aids in the successful treatment of edentulous patients with a fixed implant restoration. As such, an IVJ is included with all fixed full-arch implant cases at Glidewell Laboratories, including the BruxZir® Full-Arch Implant Prosthesis.
The IVJ method ... leads to a more accurate master cast and the fabrication of a final prosthesis that achieves a passive fit.