Fig. 10-199. The case is processed in acrylic and gold and includes small set screws that secure the superstructure to the mesostructure. (Courtesy Herman W. Goodman Dental Laboratories, Inc.)

Fig. 10-200. With specially designed screwdrivers, the small set screws secure the superstructure to the underlying mesostructure.

Maxillary enrincsennc imnlant interventinnc 439

facings were processed to the labial and buccal surfaces. Set screws were screwed through the obliquely set channels of the superstructure and into the mesostructure (Fig. 10-199).

On the following visit the mesostructure was placed over the teeth and the superstructure attached to the mesostructure by screwing the set screws into place with a specially designed screw-driver (Fig. 10-200). After all adjustments were made and the prosthesis fitted properly, both the superstructure and mesostructure were removed.

The teeth, the inside of the mesostructure, and the superstructure were thoroughly dried and the mesostructure was then carefully cemented over the abutment teeth with oxyphosphate of zinc cement. To make sure that the mesostructure was seated properly, the superstructure was immediately placed over the mesostructure for a few moments. However, before placing the superstructure over the mesostructure, the unset cement around the mesostructure crowns was wiped off to prevent the superstructure from sealing to it.

When the cement hardened, all excess was re-moved. Some form of soft temporary cement was placed inside the dry superstructure crowns, and the superstructure was seated firmly into position (Fig. 10-201) . When this cement hardened, the set screws were fastened through the central incisor crowns and into the mesostructure, and cold cure acrylic was placed over the set screws, covering the implants so that they would not loosen (Fig. 10-202). If the bridge ever needs to be removed, the acrylic can be drilled out to expose the heads of the set screws.

The remaining portions of the prosthesis were

Fig. 10-201. The superstructure in place.

Fig. 10-202. Acrylic was mixed and placed over the holes made inside the two central incisors to further lock the set screws to the prosthesis.