. Oral pathology and practice. A text-book for the use of students in dental colleges and a hand-book for dental practitioners. Section Removed to showSecondary Formations in the Pulp Chamber above the , Cervix of tusk ; b, c, d, e, Masses of secondary formation. 220 ORAL PATHOLOGY AND PRACTICE. of the calcified mass may be hyaline, but the structure, when care-fully studied, will be found to be essentially dentinal. The study of comparative dental anatomy will materiallyassist in a comprehension of these anomalies. In certain animalssecondary dentine, or tooth-bone, is very common. This
. Oral pathology and practice. A text-book for the use of students in dental colleges and a hand-book for dental practitioners. Section Removed to showSecondary Formations in the Pulp Chamber above the , Cervix of tusk ; b, c, d, e, Masses of secondary formation. 220 ORAL PATHOLOGY AND PRACTICE. of the calcified mass may be hyaline, but the structure, when care-fully studied, will be found to be essentially dentinal. The study of comparative dental anatomy will materiallyassist in a comprehension of these anomalies. In certain animalssecondary dentine, or tooth-bone, is very common. This isespecially the case with some of the monophyodonts. The per-sistent pulp chambers of the sperm whale (Physeter macrocephalus)are very frequently lined or partially filled with secondarydentinal formations, and some of them make very beautiful objectswhen polished. (See Fig. 59.) The long incisors of the elephant,the so-called tusks, are frequently wounded by the hunter near theirinsertion, the bullets remaining in the persistent pulps. This mayresult in the destruction of the vascular portion of the tooth, but Fig. Fossil Fragment of the Tusk of Elephas primigenius—in^. Hairy Mammoth—whichhad been partially fractured during llfe and repaired and strengthened bySecondary Deposits. The fracture was across the base at a ; the part between the lines at b and c was a second-ary deposit. (From a specimen in the Buffalo College Museum.) much more frequently the consequence is the deposition about thewound of secondary dentine, which perhaps will entirely inclose andsegregate the original cause of irritation, and form septa across thepulp chamber. With the continuous growth of the tooth or tuskthis is carried forward, until, perhaps many years subsequently,when the animal is killed and its tusk falls into the hands of theivory cutters, the original bullet, with the secondary formationabout it, is found in the solid ivory, perhaps one or two feet fromthe skull. (See Figs. 60
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