Good Bone Under Sinus

Unfortunately, a tall ridge is rare in posterior edentulous situations. The factors contributing to tooth loss also encourage sinus expansion; and the more bone loss, the less opportunity for using a bladevent. Only occasionally does the implantologist see enough bone under the sinus to accept one of the deeper bladevent designs. In most of these situations, the ridge, even though tall, will be narrow or knife-edge. If a knife-edge ridge must be reduced to obtain the minimal 2.5 mm width, a shorter, or "shallower," bladevent design must be substituted.

The Totally Edentulous Maxilla

When a radiograph indicates that a good amount of bone (1) remains under the sinus, an appropriate design is selected by placing the potential implants or a transparent sheet bearing implant outlines over the radiograph.'' Manufacturers supply special maxillary designs, shaped to accommodate sinus variations. A double-posted design is desirable, with the body of the blade — from leading edge to post bottom (2) — tall enough to fall just short of the sinus (3). This provides two abutments in a single surgical site, and in prosthodontically desirable locations: the second bicuspid and the second molar.

The socket begins slightly palatal to the crest (4), and is angled slightly palatally (5). In a good ridge, the palatal inclination should not threaten the palatine vessels (6) .

Very likely, the bone is porous, necessitating drilling a socket whose depth is less (7) than the bladevent measures from the bottom of its post to its leading edge (8). The legs of the blade-vent will break the few remaining bony bridges as the implant is tapped to its proper depth.

7

'Implants International—N.Y.

'Implants Research Corp.—Pennsauken, N.J.

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