The Totally Edentulous Maxillae:

The One-Piece Pterygoid Implant

Using the hamular notch-pterygoid process area has permitted the designing of a relatively lightweight subperiosteal implant. Basically three areas are used. Anterior support derives from a flat, fenestrated plate below the anterior nasal spine (1). Originally, a broad palatal strut (2) rested on the palate with an extension (3) passing over the crest in each canine region to terminate on the labial surface of the crest. Posteriorly, a strut (4) extends bilaterally along the palatal surface of the residual ridge. It passes back into the hamular notch area (5), wraps around the tuberosity, and extends anteriorly on the buccal surface (6) of the tuberosity as far as the character of the underlying bone permits. This under-lying bone must be cancellous, not invaded by the sinus. Today, the palatal strut is eliminated.

The restoration is borne on a bar with posts (7) fabricated as part of the implant. The bar passes outside the soft tissues, well above the bony crest, and thus no weight is put upon the fragile crestal bone. The bar arises posteriorly from a bucco-palatal cross-strut (8) in the tuberosity area and continues anteriorly above the soft tissues to the canine area where it deflects toward the crest to terminate on the anterior extensions of the implant. The anterior labial strut usually gives rise to one or more "wings" that join together beneath the anterior nasal spine (9) that resist lateral rocking.

As are all other types of subperiosteal implants, the full arch pterygoid extension implant is fabricated from a direct impression of the exposed bone.

An accurate bone impression requires fully exposing an area slightly longer than the intended subperiosteal implant site to adequately visualize the site and adequately manipulate the impression material. Posteriorly, the incision begins in the hamular notch area (10), palatal to the coronoid bulge (11) .

Caution: Great care must be taken in incising and reflecting tissues and handling impression material near the superficial vessels emerging from the greater and lesser palatine foramina (12). Also, the narrow tendinous strap (13) over the hamulus should not be disturbed.

Before the soft tissues are reflected and swell, the thickness of those that will lie between the bar and the crest should be measured so that the bar will sit above the soft tissues when they

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