bladevents specifically designed for shallow alveolar bone height, the sliding ramus or sliding cable implant and, to a more limited extent, the standard unilateral subperiosteal implant. When as many as six anterior teeth still exist, a universal subperiosteal implant spanning the entire arch rather than two individual unilateral subperiosteal implants is sometimes used.

Good Bone Above the Mandibular Canal

A good many patients present themselves with an adequate amount of bone above the mandibular canal, thus enabling one of the deeper bladevents to be inserted (1). Often, too, however, the ridge, even though tall, will be narrow or knife-edged (2) . A knife-edge ridge must be reduced to obtain the minimal 2.5 width (3), consequently a shorter, or "shallowed" bladevent design must be substituted (4) in order to avoid the mandibular canal (5).

Very Little Bone Above the Canal

In those cases where there is a near exposure of the mandibular canal because of severe bone loss following tooth extractions, either blades or subperiosteal implants might be facilitated depending on several factors:

If the ridge posteriorly is wide buccolingually with no apparent undercut beneath the mylohyoid ridge (1), then a blade can be inserted lingual to the canal and much deeper than the canal depth with no fear of causing a paresthesia (2). Extensive studies by

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