Dental Prosthetic System: Titanium Framework and Overlay Structure

Unlike other monolithic solutions, this prosthesis has the strength of titanium along with the flexibility of a milled overlay from either PMMA or zirconia. The overlay options not only allow the patient, clinician, and laboratory to choose the material that fits their needs today (i.e., price, esthetics, wear concerns) but they also provide the opportunity to repair, replace, or upgrade in the future without having to replace the titanium framework.

The overlay is a direct duplicate of the customer’s diagnostic wax-up (Figure 1). The final esthetics and occlusion must be included in the diagnostic wax-up or denture tooth setup. The position of the denture teeth, gingival contours, and occlusion must be accurate and approved by the patient during a try-in. Also, the inclusion of 2 screw-retained copings ensures the diagnostic wax-up is precisely positioned during scanning and that the occlusal scheme is accurately captured.

On the basis of the digital data of the stone cast and diagnostic wax-up, the dentist and laboratory technician design the framework and overlay structure for review. A unique mating scheme is designed into the framework and overlay (Figure 2).

Once approved, the dentist or laboratory can choose to have the restoration delivered in a ready-to-install state. This means that the framework and overlay have been cemented, the gingival mask has been applied, and the restoration has been polished ready for installation. The other option is to have the restoration delivered in a pre-finished state, in which case the dentist or laboratory technician will handle the cementation, apply the gingival mask, and perform the final polishing step prior to installation.

If the pre-finished option is chosen, the milled framework and overlay are delivered separately. The gingival portion of the overlay has been cut back in preparation for the application of the gingival mask and is ready for the required bench work to finish the prosthesis.

Both mating surfaces are sandblasted with an aluminous oxide, and a thin coat of a resin-bonding agent is applied to both surfaces (Figure 3 and Figure 4).

The screw access holes of both the overlay and framework are sealed with wax, and permanent resin cement is applied to the mating surface of the overlay (Figure 5). The overlay is tightly positioned onto the framework, ensuring no gaps are between them (Figure 6).

Residual wax and cement are removed, and the framework and overlay are returned to the master model to check the occlusion. Now it is ready for the gingival mask to be applied and contoured for the desired esthetics.

A resin-bonding agent is applied to the gingival cutback portion of the overlay, and sheets of denture base material are cut, contoured, and cured to create the desired gingival contours and esthetics of the prosthesis (Figure 7 and Figure 8). During the initial design phase, the dentist or laboratory technician chooses whether the final prosthesis will be fully wrapped or have a metal base. This decision will determine whether additional denture base material will be applied to the intaglio surface of the restoration.

Once all gingival surfaces are cured, the denture base material and overlay are substantially bonded as one and can be easily modified to achieve the required clinical contours. Next, the overlay contours are smoothed and polished, and the prosthesis is ready to be delivered (Figure 9).

Similar to a traditional hybrid, the prosthesis is attached to the implants/abutments by means of a screw and torqued per the implant manufacturer’s directions (Figure 10). The occlusion is checked and modified if necessary, and the screw access holes are sealed utilizing a cotton pellet and flowable composite.

Unlike other monolithic restorations, if this restoration needs replacement, the overlay can be removed easily from the framework and replaced. The overlay is simply re-milled from the stored CAD files and delivered to the clinician or laboratory. The system is also somewhat future proof with the option to replace with the same material or another material.

This streamlined replacement process also enables the potential of a single office visit for repair or replacement. The dentist or laboratory can contact the manufacturer and have the new overlay milled and delivered in preparation for the patient’s visit. While in the chair, the restoration can be removed and taken to the bench, and with the application of heat the cement bond can be broken.

Once the previous overlay has been removed, the framework is cleaned and blasted to remove residual resin and is prepared for cementation of the new overlay. When cemented and any necessary gingival mask is applied, the restoration is ready to be re-installed into the patient’s mouth—all in one visit.

Finally, this also allows for a planned replacement strategy for those patients who have accelerated wear or damage due to bruxism. With this solution, a ready-to-install overlay can be in the patient’s tray ready for delivery.

Carl W. Schulter, DDS, is the Director of Restorative Dentistry at the Dental Implant Aesthetic Center in Memphis, Tennessee.

Disclaimer: The statements and opinions contained in the preceding material are not of the editors, publisher, or the Editorial Board of Inside Dental Technology.

For more information, contact:
Cagenix
cagenix.com
866-964-5736