3. Fibrous Odontomas.
—These consist of condensed connective tissue in a developing tooth, presenting as a tumor with a firm outer wall and a loose inner texture, blending at the root of the tooth with the dental papilla and indistinguishable from it. The developing tooth thus becomes enclosed within the capsule before it protrudes from the gum. These tumors are most common in ruminants, being often multiple.
4. Cementoma.
—A tumor of fibrous character whose capsule has ossified or calcified, the developing tooth thus becoming embedded in a mass of dental cementum. These tumors occur most frequently in horses.
5. Compound Follicular Odontomas.
—These are tumors containing a number of masses of cementum resembling small teeth, or even amounting to well-formed but ill-shaped teeth composed of all three dental elements. In such a tumor teeth may be found in great numbers. They occur in the human subject as well as in animals.
6. Radicular Odontomas.
—These are tumors which arise after the crown of the tooth has been completed and while its roots are yet in process of formation. The crown, being unalterable enamel, does not enter into the composition of these growths, which then consists of dentine and cementum in varying proportions. They are rare in man, but frequent in other animals, and often multiple.
7. Composite Odontomas.
—These are hard tumors, bearing little or no resemblance in shape to normal teeth, occurring in the jaws, consisting of a conglomeration of enamel, dentine, and cementum, presenting abnormal growth of all the elements of the tooth germ. So far this tumor has only been found in man.