422 Theories and techniques of oral implantology

Fig. 10-136. A, A ratchet is used to screw in the vent-plant. Only three existing teeth prevail. B, Two internally threaded vent-plants are set into the bone. Their shafts barely extend out of the fibromucosal tissue.

Fig. 10-137. Threadless screws are attached inside the internally threaded vent-plants with sticky wax.

thesis that constantly irritated her fibromucosal tissue, which became progressively thicker as the underlying alveolar bone resorbed.

The patient's jaw was carefully evaluated by x-ray studies, and internally threaded implants were chosen for the anterior implants and triplants for the posterior areas.

Because internally threaded vent-plants were to be used, they had to be inserted before the impression for the template was taken (Fig. 10-136) . The

Fig. 10-138. A plaster index is taken picking up the three castings and the two threadless screws. Interchangeable implant shafts are placed inside the index and attached to the two threadless screws with wax.

threads of the set screws were trimmed away so that the screws could be easily inserted into and pulled out of the implants. Sticky wax was applied to the threadless screws, and they were set inside the implants with their heads protruding about 4 mm. (Fig. 10-137).

A wax interocclusal record and a plaster index, including the gold veneer crown castings and impressions of the implant shafts with their protruding screws, were taken. The set screws are used to facilitate laboratory procedures (Fig. 10-138). If the screws are to be used only to fasten the template to the implants, vertical posts to act as supporting pontics for the final prosthesis must also be included in the wax-up. Obviously, if the screws are to pass through the superstructure crowns down into the implants, the vertical posts are not needed.

The template was cast in gold and soldered to the veneer crown castings. The castings were then processed with acrylic facings. The finished substructure included the processed veneer crowns soldered together, the gold template attached to the crowns, and holes in the template corresponding to the hollow implant shafts that would allow passage of the set screws. A temporary acrylic splint was also fabricated at this time (Fig. 10-139) .

The substructure was then placed in the mouth and the bite adjusted on the right side, where the soldered veneer crowns existed. The set screws were screwed through the template and into the implants until their heads were flush with the template (Fig.