214 Theories and techniques of oral implantology

age. They are usually small and asymptomatic, rarely becoming large enough to produce a jaw deformity.

There are two general types of odontoma, the division being based upon the radiographic, gross, and microscopic characteristics of the lesion. The compound, or compound composite, odontoma is a very dense, clearly defined lesion often surrounded by a thin radiolucent outline (Fig. 6-21). Within the radiopacity crude teeth of various sizes and shapes may often be seen. Under the microscope the structure of these shows a central core of pulp tissue surrounded by a shell of dentin partially covered by enamel.

The other type of odontoma, the complex or complex composite odontoma, is a conglomeration of dentin, enamel, enamel matrix, cementum, and pulp tissue. In x-rays, the lesion appears to be equally disorganized, without any specific shape or form (Fig. 6-22).

A cyst may occasionally be associated with an odontoma. This cyst develops from the enamel organ or organs that produced the odontoma and is usually lined by stratified squamous epithelium.

An odontoma is separated from normal bone by a thin layer of connective tissue. This facilitates its removal. If a cyst accompanies the odontoma, it should also be removed.

Nonodontogenic tumors and pseudotumors. Numerous kinds of tumors that do not arise from the dental lamina or its derivatives may occur in the jaws. These may develop from the bone or spread

Fig. 6-23. A giant cell reparative tumor is a well-defined radiolucent lesion composed of liver-like tissue. It usually occurs in the mandible. (From Kolas, S., and others: Radio-graphic patterns of resorption seen in some gnathodental hard-tissue disturbances, Dent. Clin. N. Amer., November, 1968.)

to it from the soft tissues. They may be single or multiple, benign or malignant.

Some of the benign tumors of nonodontogenic origin are the giant cell reparative granuloma, myxoma, chondroma, osteoma, oral tori, hemangioma of bone, and various central fibroosseous lesions. The treatment of these lesions varies, depending upon the shape, size, and behavior of the lesion. For example, the giant cell reparative tumor a jaw defect consisting of radiolucent liver-like tissue that contains multinucleated giant cells   may be success-fully treated by local curettage. Because the lesion is well defined (Fig. 6-23), recurrences are rare. The true myxoma, on the other hand, is not encapsulated and infiltrates the marrow (Fig. 6-24). For this reason it is very difficult to remove totally and thus prevent recurrences. Other seemingly innocent benign lesions, like the chondroma, not only infiltrate the bone marrow, making it difficult to eradicate them, but are precancerous.

Some benign tumors need not be removed if they remain small or do not cause tooth displacement. Small oral tori are an example. These are exostoses, or outgrowths of bone, that may occur in the mid-line of the palate (torus palatinus) or on the lingual surface of the mandible (torus mandibularis). Al-most 20% of all Americans, usually women, have torus palatinus, and about 8% of Americans of both sexes have torus mandibularis. Unless these lesions grow very large, they are harmless and need not be removed. However, even small tori present prob-

Fig. 6-24. A multilocular myxoma, although benign, is difficult to eradicate because it infiltrates the marrow. (From Kolas, S., and others: Radiographic patterns of resorption seen in some gnathodental hard-tissue disturbances, Dent. Clin. N. Amer., November, 1968.)