374 Theories and techniques of oral implantology

Fig. 9-133. The denture with processed acrylic teeth is seen in position.

Fig. 9-134. An intraoral postoperative x-ray.

Fig. 9-135. The bifid implants of Bordon and Azoulay. (From Linkow, L. I.: Clinical evaluation of the various designed endosseous implants, J. Oral Implant Transplant Surg. 12:35-46, 1966.)

completely edentulous mandible. If there is not enough bone above the mandibular canal, a subperiosteal implant with a removable snap-on denture can be very successful. When there is enough bone, the patient can usually tolerate a conventional denture and implants are not needed. In those cases, however, where the patient has a full or partial complement of natural teeth in the maxilla, a conventional lower denture is usually not satisfactory. It is in such situations that endosseous implants benefit the patient. Vertical post type implants, blades, triplants, bifid implants, or a combination can be utilized. The use of a template in completely edentulous mandibles is not compulsory, as it is when using triplants in the maxilla.

Case 14

Full arch splint for an edentulous mandible using bifid implants

The architectural design of some implants limits their use to certain areas in the maxilla or mandible. One example of a good, although limited, design is the bifid implant of Bordon and Azoulay (Fig. 9-135). Because of its design, the bifid must be set into the jaw in pairs, rather than as a single implant, to obtain maximum retention. A single one can be pulled out without too much resistance. However, when two are set into bone so that their endosseous pin portions are going in opposite directions and are splinted in the oral cavity with a fixed partial denture or connecting bar attachment, they become extremely retentive.

The location of bifid implants is limited mostly to the anterior portions of the maxillae and mandible, from cuspid to cuspid. They work well in resorbed edentulous mandibles where, for a number of reasons, a subperiosteal implant is contraindicated. Bifids have also been successful in the anterior regions of both jaws when the ridges are extremely narrow.

In this case, bifid implants were used as the abutnients in an edentulous mandible. Because the bar between the two legs of each bifid must sit directly on bone, rather like a subperiosteal implant, the crest of the anterior portion of the alveolar ridge was exposed by incising and retracting the mucosal tissue with a scalpel (Fig. 9-136).

Using an acrylic template guide against the crest of the ridge in the cuspid areas, a spiraled bur the same diameter as an implant leg was drilled deep into the bone. The bur was then removed and a duplicate pin, the same diameter and length as the implant leg, was placed through the template and