to expose the implant site and, in some cases, to take impressions. The amount and shape of the bone in the proposed implant site will determine the type of implant and its insertion. Sometimes surgical modification of the hard or soft tissues is desirable to facilitate implant insertion or the seating of the restoration. Above all, the goal of implant surgery is the seating of stable abutments with a minimum of trauma. Implant surgery should be neither so complicated nor extensive that local nondental structures are threatened or prolonged healing periods are required. Simple, direct surgery based upon maximum utilization of local morphology is essential.

In most cases, the operative site is limited to the residual ridge, formed by a prominence or process of the mandible. The mandible is a strong, reinforced bone firmly fused at its midline, the symphasis menti. It is the only movable bone of the face. Its actions against the maxillae permit the mastication of solid foods and play a major role in speech formation. The mandible provides the skeletal framework for organs that participate in eating, swallowing and speaking. Among the most important of these, to the dentist, are the teeth.

The mandible consists of a horseshoe-shaped body (1), each free end of which ascends upward and backward at a sharp angle from the body as a mandibular ramus (2). The superior aspect of the body is the alveolar ridge (3) , which varies in height, width, and inclination. Its lower border is thicker than the portions of the body, and smoothly rounded.

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