IEKEGULAEITIES IN THE KOWS OF TEETH. 89 



the superior molars, and the inner margins of the lower, be- 

 come sharp and jagged. This tends to induce excoriations 

 in the mouth; the movements become more and more limited, 

 and the irregularities more marked. Bouley refers to a spe- 

 cimen in the Alfort Museum, in which the tables of the teeth 

 form such inclined planes as to be parallel with each other, 

 and crossing each other like scissor-blades. The cause of 

 this, according to Professor Bouley's observations on the speci- 

 men, appears to have been caries of two molars which, having 

 limited the action of the jaws to one side, led to growth on 

 the opposite side of the teeth, and gradually the confined 

 movements of the jaws favoured the full development 01 the 

 deformity. 



The lower molar teeth being smaller than the upper, are 

 occasionally most worn, and this often leads to excessive 

 wear of the middle molars on each side, the anterior and 

 posterior ones remaining larger. The middle molars may be 

 worn down to the gunis, and the latter then sustain injury. 



I have before mentioned, that from a molar tooth not being 

 worn over its whole surface, a portion may exceed a natural 

 length. This is sometimes the case with an entire tooth, 

 when the opposite one is absent. 



During my experience in Scotland, I have met with a large 

 number of colts two, three, and four years of age, suffering from 

 the displacement of a temporary molar, the non-eruption of 

 the permanent tooth which should have taken its place, and 

 the production of much irritation from food and other sub- 

 stances entering the empty socket. Sometimes the opposite 

 tooth grows up, as seen in Fig. 46. 



The annexed illustration shows how a projecting molar tooth 

 roay, by pressure, induce inflammation of the upper jaw, 

 liberation, and a discharge by the nose, which is often offen- 

 sive, and very difficult to cure. Before such destruction has 



