546 Theories and techniques of oral implantology

holes with a tapered diamond stone so that the denture easily fits over the posts. Also, the denture must not contact the underlying tissues, so it be-comes necessary to reduce the tissue-bearing surface of the denture between the four holes.

Fig. 12-32. Healing of the soft tissues covering the implant usually is completed 3 to 6 weeks after its insertion.

Making the impression for the final implant denture

After about 3 to 6 weeks, the implant should have completely set and the surrounding tissues should be sufficiently healed to take the final "pick-up" impression for the final implant prosthesis (Fig. 12-32) . The superstructure framework is first placed over the four implant abutments (Fig. 12-33), and an accurate wax or stone occlusal record of centric relation is taken and the vertical dimension established (Fig. 12-34) . The superstructure is then picked up with one of the elastic impression materials (Fig. 12-35) or with one of the alginate materials (Fig. 12-36). All the soft tissue underneath the superstructure should be included in this impression. Instead of processing the denture, a wax-up of acrylic teeth fitted to the metallic superstructure should be tried during the next visit so that the bite, articulation, vertical dimension, and balancing of the case can be corrected (Fig. 12-37). Finally, the com-

Fig. 12-33. The superstructure framework is placed over the protruding implant posts.

Fig. 12-34. A wax interocclusal record of centric relation is taken.

Fig. 12-35. The superstructure framework is then "picked up" with an elastic impression.

Fig. 12-36. Sometimes an alginate impression is used to "pick up" the superstructure.