rence, the width of each may differ considerably. Longer spans tend to be narrower and more irregular than shorter spans, for obvious reasons. The presence of some teeth helps divide the ridge into areas that can be evaluated separately and approached accordingly.

Adapting to a Limited, Wide Site

A generously flared anterior area (6) can usually accept any of several standard bladevents, the choice of which depends upon matching the mesio-distal length (7) of the implant and its height (8) to the available bone. Neither shoulder of the implant should approach too closely the narrowed portion of the ridge (9). A slip could fracture the plates, and bone dieback can weaken them.

The area above the crest proper should be carefully examined for. concavities and other flaws. The narrowed area should have vertical or diverging (10) mesio-distal dimensions, not converging (11) ones. An undetected convergency can mean penetrating the labial plate during drilling (12), or fracturing it during implant insertion (13). This is another reason why it is usually wise to angle the socket slightly palatally.

In a wide, even ridge, the socket and bladevent follow the curve of the dental arch. However, in an irregular ridge, it may be preferable to make the socket follow the swell of the wider area (14). This would be a particularly handy approach when the tip of the implant's shoulders threaten to impinge (15) upon the labial plates. The slightly exaggerated curving could produce a safety margin in such a tight situation.

Caution: If the socket's curvature would bring the bladevent's shoulders almost flush against the labial (16) and palatal plates (17), a shorter bladevent design should be substituted.

The bladevent is bent with two cone socket pliers to fit the socket passively, without binding or jamming at any point. It is inserted with manual pressure, and the angle of its post compared to those of other abutments. Perhaps curving the socket away from the ideal dental arch line has set the post off-center. This can be easily compensated in prosthesis design.

Caution: Trial insertions and removals of the implant should be kept to a minimum in problem ridges to avoid accidental fracturing.

Caution: Also because of the fracturing potential, the socket should be drilled to its entire depth, even when the bone is porous.

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