amount of bone should be removed. Reducing the alveolar ridge increases the proximity to anatomic landmarks (3).

The implant socket is created in the reduced crest, being closer to the lingual surface than the labial surface, if possible. Because of a double-posted bladevent's length, the socket will curve around the dental arch.

Caution: The bone above the mandibular canal may be more porous than that in the canine-incisor area. The socket should be drilled accordingly, being left slightly shallower in the porous area. When seating the bladevent balanced tapping is essential. The blade should not ride up and down in its socket. Both posts of the bladevent should be flush with the reduced crest (4) .

Sometimes anteriorly, a narrow "waist" extending high on the ridge can divide the ridge into two implant sites. Because each site is separate, various "tricks" may be used to take better advantage of the remaining bone. The sockets may follow the dental arch (5) ; or, a groove may be angled (6) or curved (7) across the dental arch. Angling or curving a bladevent in a short space is recommended only for the experienced operator.

Sometimes it is possible to reduce (8) the more anterior site to extend a larger implant into the narrow waist. It is usually unwise to reduce the ridge too close to anatonacal landmarks of the mandible such as the mental foramen (9).

Caution: Do not improperly seat one implant in order to achieve even post height. Each implant must be buried up to the bottom of its post. Differences in post height (10), (11), can be easily compensated in the prosthesis.

Because each socket should be angled most advantageously into its site, the implants may be seated at different angles. Their posts should be adjusted accordingly (12,13), so that each is

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