uneven, with sharp walls. The open-socket bladevent is appropriate for this situation. The sharp walls may be retained to avoid countersinking the implant posts, although in many cases the sharp angles taper to less than 2.5 mm and must be remodeled.

When used in an even ridge with no dips or open sockets, the recessed shoulder allows a tall shelf of bone to regrow over it. The bony shelf is a bonus against tongue thrusts and other forces tending to cause lateral displacement.

Because the open-socket bladevent is a deep-bodied design, its use is more utilized in the mandible to anterior situations, al-though it is often used as posterior abutments where ample bone height exists.

Canine Pillar Implants

The canine pillar is a versatile site for the single-tooth implant. The pillar is a column of bone that tends to remain relatively substantial even after extensive bone loss elsewhere in the ridge.

Although most patients have enough bone in this area to accept some type of bladevent, in a few cases the bone is so flawed or shallow that an endosteal implant is contraindicated. Resorption may have extensively flattened or deformed the ridge, or left a knife-edge ridge that cannot be reduced to accept a blade.

The shape of the bone at the crest determines how the socket will be made. Because the implant has narrow shoulders, it can be set in a very short space. Its socket can be aligned along the dental arch (1), with its face (2) following the arch line. Cross sections (3) and mid sagittal (4) cross-sections show that an implant set in this fashion has good bony resistance to lateral forces.

The implant site also can be angled across the arch (5), Profile (6), sagittal (7), and coronal (8) sections indicate adequate bony

support in this position.

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