Evaluating the implant candidate 237

the jaws, implants are generally contraindicated. However, if the dentist has been assured by a medical doctor that the condition has been arrested in a mature patient, a blade may be inserted in a bony area. Because of its greater surface contact, the blade may remain secure for some time unless conditions elsewhere in the jaw result in occlusal shifts that would unbalance the restoration.

Osteoid-osteomas consist of small nidi of osteoid tissue surrounded by a zone of sclerotic bone.

Eosinophilic granuloma is a solitary lytic lesion occurring in young persons. Because of the patient's age, such a tumor will rarely be seen by the implantologist when contemplating implants but may be seen during the course of other forms of dental work.

Most of the benign tumors are treated by curettage or resection. If implants are to be placed in the areas formerly occupied by a benign tumor, the new bone must have completely regenerated and matured in the site before the implant intervention.

Malignant tumors. Among the malignant bone tumors affecting the jaws are osteogenic sarcoma, chondrosarcoma, Ewing's sarcoma, malignant giant cell tumor, and myeloma.

Osteogenic sarcoma is the most common and serious of the malignant tumors. It usually involves the diaphysis of long bones but may also involve the flat bones of the skull, pelvis, and spine. Rarely are the jaws involved, but when they are the mandible is usually the afflicted jaw (Fig. 6-47).

In osteogenic sarcoma the malignant cells invade normal bone, destroying it and forming osteoid tis-

Fig. 6-45. The downward convexity with a localized loss of the cortical plate at this point only always indicates fibrous dysplasia. (From Worth, H. M.: Principles and practice of oral radiographic interpretation. Copyright 1963 by Year Book Medical Publishers, Inc. Used by permission.)

sue and new bone. The growth is wild and uncontrolled, usually penetrating the cortical plate and extending beyond it. The new bone is characterized by radiating spicules. The tumor can also extend by way of the bone marrow. Sometimes, however, the lesion is largely lytic with very little formation of bone.

The first symptom of osteogenic sarcoma is pain, followed by swelling. As with most cancers whose first symptom is pain, the tumor may be fairly exten-

Fig. 6-46. Gross malformation and enlargement of the same mandible as a result of fibrous dysplasia. Because this enlargement combined with bone swellings elsewhere in the face give the patient a leonine appearance, the indiscriminate term "leontiasis ossea" is sometimes used to describe such a deformity. (From Worth, H. M.: Principles and practice of oral radiographic interpretation. Copyright 1963 by Year Book Medical Publishers, Inc. Used by permission.)