DISCUSSION.
The major causes of mandibular discontinuity are tumor resection, trauma, gunshot wounds, and, to a lesser degree, osteoradionecrosis and osteomyelitis. The loss of a mandiburement and serious disabilities, including impairment of chewing, swallowing, speaking, and drooling. The degree of disability varies with the size and location of the defects. 1,11 Prosthetic rehabilitation in these patients poses a real problem. Often, the remaining mandibular segment is medially displaced and in an inconsistent occlusal position. A denture worn on the remaining mandibular segment is often unstable, making it difficult and painful to wear.
Therefore, the fabrication of a functional removable denture for patients who have undergone mandibular resection is often unsatisfactory without the incorporation of some type of tissue augmentation or reconstruction to restore mandibular continuity. 14 The following are some of the goals of mandibular reconstruction from the restorative dentist’s standpoint:

1. Restoration of jaw continuity. The greatest amount of mandibular form and function can be achieved only by restoration of the mandibular continuity. Restoration of mandibular form will also improve facial symmetry and denture esthetics.
2. Provision of a better prosthesis bearing area. Prosthetic rehabilitation is dependent an adequate bone height and width for proper support, retention, and stability of the prosthesis and for the restoration of a functional occlusal relationship.
3. The graft must be long lasting and able to withstand the functional demands placed on it.
4. Restoration of acceptable facial contours and esthetics. Restoring lower facial form and contour is valuable in returning the patient to a positive self-image and a productive life. The use of a prosthesis may be a positive factor in such physiological and psychological rehabilitation.

Various grafting techniques have been used for the reconstruction of mandibular defects. The vascularized graft is considered the standard of care in many institutions. The most commonly used donor sites for mandibular reconstruction are the fibula, iliac crest, scapula, and radius. Reconstructive efforts improve mandibular function, appearance, and mastication but often not to the levels expected by the patient. Combining these techniques with dental implants can enhance the prosthetic outcome of the patient after mandibular reconstruction. Therefore, if implant rehabilitation is to be anticipated, a suitable donor site must be selected for improved placement and osseointegration. Mososco et al and Frodel et al analyzed various donor sites for potential implant placement. They found the iliac crest to have consistently suitable dimensions for implantation. The scapula and then the fibula followed the iliac crest in available bone to accept dental implants in cadaver measurements. As alternatives to the iliac crest, Mososco et al1 and Frodel et al identified the fibula first and the scapula second. The radius was the least reliable donor site, particularly in females where no specimen met the criteria for implantation.
Immediate placement of dental implants during the transfer of bone has been recently popularized. The main disadvantages of immediate implant placement are improper alignment of implants caused by bone rotation and unpredictability of muscular coordination in the long term.

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