The cement, which, it must be remembered, is composed of bony tissue, sometimes undergoes a hypertrophy to which the name Exostosis or Osteoma is often given. This is scarcely a true bony tumour, but originates rather in chronic inflammation of the cement, leading to a considerable new-formation of bony tissue. In this way are formed prominent tuberous outgrowths from the roots of the teeth, which may be localized to one part of the fang, or cover a considerable portion of it, or even the whole root portion of the tooth. In the latter case it is as if the root were enlarged by rough accretions on its surface. These so-called exostoses sometimes offer serious resistance to the extraction of the teeth.

Another form of tumour connected with the teeth is that which Virchow has called the Odontoma. This tumour arises in connection with teeth retained in the alveoli by faulty development. The tumours are composed of dentine and enamel, and are of small size and rare occurrence.

Cysts of the jaws have already been referred to (p. 578) as usually taking origin in connection with the teeth or their rudiments, and Cancers have occasionally a similar origin (p. 579).

Literature

Smale and Colyer, Diseases and injuries of the teeth, 1893; Leber u. Rottenstein, Unters. iiber d. Caries d. Ztihne, 1867; Wedl, Path. d. Zahne, 1870, transl., 1873; Klebs, Arch. f. exper. Path., v.; Tomes, Syst. of dental surg., 1877; Miller, Die Mikro-organismen der Mundhohle, 1892; Salter, in Holmes' Surg., v., 1883; Eve, (Cysts of jaws, with literature) Brit. Med. Jour., 1883, i.; Malassez, Arch. d. Phys., v., 1885; Hutchinson, (Syphilitic teeth) Syphilis, 1887; Sutton, (Odontoma) Tumours innocent and malignant, 1893, p. 31; Chibret, Arch, de med. exp., 1894.