bone to flank it, especially since most of the concavities exist on the labial and buccal surfaces of the mandible bringing the buccal surface of the bladevent even closer to these surfaces. Counter-sinking of the blade is often necessary, however, by reducing the bone on the lingual aspect of the crest which is interfering with proper seating of the blade, since the lingual aspect of the crest always contains more bone height than the labial aspect since teeth are mostly lost at the expense of the labial or buccal bone.

Sometimes extreme resorption of bone in the mandible involving its height and width, especially the anterior labial undercut area makes it necessary to use a method of subperiosteal tunneling using autogenous bone from either the posterior ridge or opposing ridge or from the medullary bone of one or both of the ileums of the patient and tunnelling it into the undercut areas or at the crest. A single vertical incision at the midline of the mandible is all that is needed while the tunneling is created to the left and right side of it in a horizontal direction. The incision is closed with a few sutures.

The patient should not wear a denture for at least three to six months to avoid any unnecessary mechanical irritation in the graft area. Antibiotics are prescribed. The graft area gradually becomes smooth by selective resorption and replacement of new bone occurs within six months. At that time the five piece symphyseal-rami implant system can be used successfully giving the patient a fixed prosthesis.

Surgical Hints

A. Handling of Soft Tissues

When performing surgical interventions of any sort one must have a complete understanding of the soft and hard tissues involved. This was clearly discussed and illustrated in the second and third chapters of my previously published book, "Theories and Techniques of Oral Implantology", C.V. Mosby Co., St. Louis, Missouri.

To include it in as few words as possible I will say the following:

1. An implant, whether it be a screw, pin or blade type should never be placed directly through the soft tissues and into the bone without first incising and reflecting the tissues to expose the under-

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