ANIMAL DENTISTRY 



155 



two events the following chain of abnormalities occur: (i) 

 extension of the inflammation to the blood vessel, nerves and 

 periosteum ; (2) abscess formation at the root pointing 

 through the peridental plate into the sinuses or surface of 

 the skull; (3) destruction of the blood supply of the tooth; 

 (4) death, desiccation and splitting of the tooth; (5) im- 

 paction and decomposition of food in the cavity between 

 the split section; (6) osteitis and necrosis of the alveolar 

 border from pressure of the split sections ; (7) self-extrac- 

 tion. The duration of the process is from three to fifteen 

 years. The above chain of conditions is, of course, not 

 followed to the letter in every instance. For example, an 



Fig. 109. 



intense periostitis may rapidly loosen a tooth from its 

 cavity and, by admitting infectious matter around it, pro- 

 duce extensive osteitis of the jaw. In the young animals the 

 great length of the tooth, and in the inferior denture, 

 gravity, prevents the self-rejection of the tooth from its 

 cavity, and as a result the loose, dead tooth perpetuates and 

 augments the inflammation and tumefaction of the sur- 

 rounding bones. This condition is seen principally in the 

 inferior molars when the primary lesion has been alveolar 

 periostitis. Primary pulpitis caused by the open infundi- 



