vertical (10) or diverging (11) mesio-distal dimensions, not con-verging (12) ones. An undetected convergency can mean penetrating the labial plate during drilling (13), or fracturing it during implant insertion (14). This is another reason why it is usually wise to make the groove slightly lingually (15) .

In a wide, even ridge the socket and bladevent follow the curve of the dental arch. However, in an irregular ridge, it may be prefer-able to make the socket follow the swell of the wider area (16). This would be a particularly handy approach when the tip of the implant shoulders threaten to impinge (17) upon the labial or lingual 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 (18) and lingual plates (19), a narrower, shorter bladevent design should be substituted and placed in center of ridge closer to the lingual side (20) .

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 groove 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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