18 VETERINARY DENTAL SURGERT. 



tine. It commences at the neck of the tooth, in very 

 thin layers, and continues to increase in thickness 

 toward the apex of the root? and corresponds in text- 

 ure to the bony framework of the same animal, and 

 is traversed by vascular canals. Where natural cav- 

 ities exist on the free portion of a tooth, as in the Her- 

 bivora, they are occupied by crusta-petrosa. The 

 cementum being less dense than the enamel, it is 

 worn away in the cavities of the tooth as fast as the 

 projections of enamel are worn down, so that the 

 grinding surface is retained during the life of the 

 animal. The cementum has tubuli and cells re- 

 sembling canaliculi and lacuna? of bones. Indeed 

 their physiological use is the same. These tubuli 

 connect with the dental fibers. 



As age increases the cementum increases in thick- 

 ness and may give rise to a bony growth or exostosis. 

 Sometimes the teeth of young animals are affected 

 by exostosis, which is due to an extraordinary develop- 

 ment of the cementum, for it is this tissue that is 

 always found in their growths. 



FIG. 4. 

 MAGNIFIED SECTION OF A CANINE TOOTH, SHOWING ITS 



INTIMATE STRUCTURE. 



i, crown; 2, 2, neck; 3, fang or root; 4, pulp cavity; 5, 

 opening by which the vessels and nerves communicate 

 with the pulp; 6,6, dentine, showing fibrous structure; 7,7, 

 enamel ; 8, 8, cement. Chauveau. 



