Exostosis

(eks-os-to'-sis). Abnormal, enlargement or growth of bone, especially a deposit of bony ti ue upon the surface of a preexisting bone. E. of the Teeth, exostosis dentium; exodontosis. An outgrowth from a tooth. The only part of a tooth subject to exostosis is the root, and the development of the affection usually commences at or near the extremity; extending from thence upward, it sometimes covers a greater or le portion of the external surface. E., Ivory, a bony outgrowth of extreme hardne and of small size, rarely exceeding that of a small walnut. It springs usually from the exterior of one of the cranial bones. Histologically, it is marked by the absence of Havers i an canals.