How to Fabricate a Hybrid Pressed Implant
There are several abutment options that can be used when restoring dental implants. Abutment choices range from stock titanium or zirconia, to ones that are custom designed. Custom options include CAD/CAM titanium or zirconia, hybrids with a titanium base and zirconia or e.max, and UCLA all-metal or metal-ceramic.
This hybrid abutment combines the strength of a titanium (Ti) base, with IPS e.max Press (lithium disilicate LS2 – 400 MPa) as the esthetic ceramic portion of the abutment. The Ti Base is the connection between the implant and ceramic.
The laboratory purchases the Ti Base used to fabricate the hybrid abutment from Ivoclar. The Ti Base is the connection between the implant and the ceramic portion of the abutment. Part of the Ti Bases extends into the implant and part extends as a “chimney” which supports the ceramic portion of the abutment. The titanium chimney, which extends inside the lithium disilicate requires a minimum height of 4.0 mm. The total height of the ceramic portion of the abutment should not exceed twice the height of the Ti Base. The laboratory may need to alter the height or shape of the Ti Base depending on the design requirements of the abutment. Once the modifications of the Ti Base are completed, the laboratory fabrication process involves waxing the desired final contour of the abutment onto the Ti Base.
During waxing, the shape and emergence profile of the subgingival portion of the abutment are designed. The margin location of the crown is established at the desired height relative to the free gingival margin. After completing the wax-up, the wax pattern is removed from the Ti Base, it is invested and burned out, and the lithium disilicate is pressed into the mold. After the investment ring has cooled, the ceramic is divested. It is then fit to the Ti Base. At this time the lithium disilicate can be contoured to refine its shape. To complete the ceramic portion of the fabrication, it is shaded, glazed, and polished.
Connecting the Ti Base and the lithium disilicate portion of the abutment can be in the laboratory or the dentist’s office, by following these steps:
1. Micro air abrade the surface of the Ti Base that will extend into the lithium disilicate, with 50 micron aluminum oxide.
2. Apply Monobond Plus for 60 seconds to the Ti Base that has been air abraded.
3. Etch the intaglio surface of the ceramic with 5 percent hydrofluoric acid for 20 seconds.
4. Ultrasonic clean in water for five minutes.
5. Apply Monobond Plus to the intaglio surface and allow it to react for 60 seconds.
6. Extra-orally the two components are luted together. Apply a thin coat of self-curing Multilink Implant luting composite to both components. This highly opacified composite is used to minimize the negative esthetic effects of the metal body inside the relatively translucent ceramic material.
7. Push the components together and remove the excess before it sets.
8. Apply glycerin to minimize the oxygen-inhibited layer of the composite.
9. After the composite has set, polish the transition from titanium to ceramic.
Using a hybrid abutment may be a good esthetic solution for implant restorations, while maintaining the strength required for a durable outcome.