Mandibular endosseous implant interventions 353

Fig. 9-62. The internally threaded vent-plant.

Fig. 9-63. The preoperative picture shows only five teeth remaining.

Case 7

Two unilateral bridges fixed to a template using internally threaded vent-plants

In this case, two separate bridges were screwed to a template incorporating full crown restorations. The implants used to secure the prosthesis were internally threaded vent-plants (Fig. 9-62) .

The patient had five teeth remaining (Fig. 9-63) . On the first visit, these were prepared for full crown restorations. On the next visit, the castings were tried and balanced. The internally threaded vent-plants were then screwed into the bone posteriorly (Fig. 9-64).

A wax bite, an alginate impression of the opposing jaw, and a full lower plaster index were made. Internally threaded duplicate shafts were placed in the plaster index, and the master stone model was poured and articulated. The small set screws protruded from the duplicate shafts just enough to be slightly short of the opposing jaw master model when the articulator was closed in centric occlusion (Fig. 9-65) . The threads of these screws were ground away so that the screws were able to be lifted out of the duplicate shafts with the wax pattern.

The castings were soldered to one another and a wax template built around the protruding set screws. The template was cast and soldered to the anterior castings. The acrylic veneer facings were then processed (Fig. 9-66). (Sometimes the two posterior templates are constructed so that their anterior sections are not rigidly soldered to the nearest crown restorations but slip over them. In this manner the entire template can be removed to expose the irnplants.)

Fig. 9-64. Veneer type castings were made for the prepared teeth and internally threaded vent-plants were set into the bone ending close to the fibromucosal tissue.

Fig. 9-65. The master stone model with the five castings and three duplicate implant shafts with their set screws attached.