A bladevent must be introduced into a ridge at least 2.5 mm wide, approximately twice the width of the bladevent's shoulder. Most knife-edge ridges can be reduced, if need be, to the desired width with a 700 XL bur (5), a heatless stone (6), or a rongeur (7).

The crest is reduced perpendicular (8) to the vertical plane (9), not perpendicular (10) to the inclination of the ridge (11), to retain the labial plate and to avoid countersinking the posts — a process requiring great care because of ease in chipping the narrow, fragile wall of the socket.

Even, rather than spot, reduction is often more practical for the totally edentulous knife-edge ridge. Even reduction permits better visualization of prospective implant sites and better access during surgery. Furthermore, almost the entire ridge will be occupied by the blades needed for adequate support. The ridge is gradually leveled by working around the entire arch (12) until adequately wide sites appear.

Caution: Although extensively reducing the ridge might produce a wider table, it also brings vital landmarks nearer the crest and limits the choice of implant. Reduce only enough to safely widen the ridge to accept the deepest-bodied bladevent appropriate to the site.

When an adequately wide table has been established, the sharp edge (13) of the ridge carefully may be rounded with a bur or stone to reduce trauma to the soft tissues that will overlie the altered bone.

An atypical drilling technique is recommended in fragile knife-edge ridges to make the socket in as few steps as is possible. The 700 XL bur is centered on the reduced ridge (14) and angled slightly toward the palate to take advantage of harder palatal bone and to avoid the typical labial concavity. The operator places his fingers (15) on each side of the site. These will brace the ridge and sense the proximity of the running bur to the labial and palatal plates. The bur is driven straight down to the entire intended depth of the socket.

10'