Mandibular endosseous implant interventions 385

extremely wide alveolar bone so that its legs can be angled far apart. Such sites are rare in a full arch, and other implants should be used in combination with triplants. In some rare cases, however, an arch completely supported by triplants may be attempted.

First, an elastic impression of the entire mandible was taken. A metal template was then processed. The template was placed over the mucosal tissue and held firmly with a denture adhesive, and radio-graphs of the jaw were taken, using the template as a guide for making the pin holes. The template was removed and the pin holes drilled through it. The perforated template was replaced, and the pins were driven through the holes one by one. The ends were built up with acrylic cores, using the brush-on technique, and then prepared for full crown restorations.

A full lower elastic impression, a wax inter-occlusal record of centric relation, and an alginate (irreversible hydrocolloid) impression of the opposing jaw were made. The master model was fabricated and articulated.

From the master model, either a full arch fixed denture can be fabricated or a connecting superstructure bar can be constructed to be cemented permanently over the acrylic cores, with the additional fabrication of a removable denture with internal attachments.

Case 19

A full arch restoration for an edentulous mandible using internally threaded implants

In this case the implants were set so that their shafts did not protrude more than 1 mm. from the fibromucosa. In this way no temporary splint was needed. A plaster index of the entire mandible was taken, and duplicate shafts were placed inside the index. From the master model, three types of restorations could have been fabricated: a mesostructure with a set of screws for insertion into the implants (the mesostructure must contain internally threaded shafts to accept the screws of the superstructure) ; only a superstructure (this is actually the full arch splint, but it contains strategically situated internal thread systems across its length for screws that will fasten the bridge directly to the internally threaded implants) ; and a template with at least four protruding vertical posts to support the fixed denture. The template itself could have been ce-

Fig. 9-166. An endentulous mandible restored with endosseous and subperiosteal implants. The implants are connected by a solid type vertical bar. (From Chercheve, R.: Les implants endo-osseoux, Paris, 1962, Librairie Maloine.)

rnented onto or screwed into the implants. The prosthesis, fabricated to conform to the peripheral scalloping of the template, was cemented over the protruding posts of the template.

Case 20

Full arch resorations for the edentulous mandible using combined endosseous and subperiosteal implants

Occasionally x-rays will reveal that the alveolar crest has unevenly resorbed. Although there may still be enough alveolar bone in the anterior region to support endosseous implants, the posterior regions have completely resorbed unilaterally or bilaterally and require subperiosteal implants.

In the case illustrated in Fig. 9-166, a subperiosteal implant was inserted posteriorly on each side, following routine subperiosteal insertion techniques. Two post type implants were inserted anteriorly, again using routine procedures. The anterior posts of the subperiosteal implants were joined to the endosseous implants by a connective bar with built-in snap attachments. Impressions were taken, and a prosthesis was constructed to be supported by the implant posts and the connecting bar spanning them.