Exostosis

Non-neoplastic bony enlargements of the jaws that have limited growth potential are collectively referred to as exostoses. Those that occur in the midline of the maxilla are known as torus palatinus, and when located on the lingual aspect of the mandible as torus mandibularis. At other sites, they have no special name. The frequency with which they occur is uncertain. An often-quoted figure for torus palatinus is 20%, for torus mandibularis approximately 10%. One survey found 29 per 1000 persons (2.9%) for all tori, a figure that seems more accurate. Palatal tori are twice as common in females as in males but there is no sex specificity for mandibular lesions. Exostoses arise early in life, as early as the first decade. The majority is present before age 40. Mandibular tori are usually bilateral and located on the lingual aspect of the mandible in the cuspid-bicuspid region. They may appear as a single nodule or as a row of confluent nodules. Their size ranges from those so small they are inconspicuous to those so large they fill the floor of the mouth. Exostoses do not present a diagnostic problem to those who are aware of their existence and are familiar with their clinical appearance. Exostoses are asymptomatic, bony hard, and covered by normal oral mucosa; thus, people are chiefly unaware of their existence. Health care workers who are unfamiliar with exostoses of the jaws are likely to overdiagnose them as tumors. Histologically they consist of medullary bone with a fatty marrow and a thin cortex. Removal is not required unless they interfere with dental prostheses.

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