them from implant procedures that primarily concern the implantologist. Intruding into the canal with a bur during implant surgery can sever the blood vessels and nerve. Fracturing the upper border of the canal during implant insertion can drive bone chips into the contents or compress them, producing great pain if the accident remains undiagnosed. Seating a bladevent too close to the nerve sometimes produces pain or numbness in hypersensitive individuals. A subperiosteal implant pressing on an exposed nerve in any portion of the ridge will produce unfortunate results.

Any surgical procedure producing more or less permanent postsurgical pain is, of course, contraindicated. Or, if pain persists after healing, its cause should be remedied.

Occlusal films taken by the author on many mandibles that were wired through the entire length of the mandibular canals and by placing wires in the center of the existing residual crests, revealed, that the mandibular nerve in the body of the mandible is always slightly buccal to the center of the residual crest.

These results clearly indicate that in shallow ridges a blade can be inserted lingual to the existing crest and way beneath the mandibular canal, without causing a parasthesia providing that there is no submandibular fossa or just a slight concavity on the lingual side of the ridge.

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