OPEEATIONS ON THE TEETH. 329 



where, instead of presenting the regular and correct natural lines, 

 the upper and lower molar arches so far disagree as to render 

 their perfect coaptation impossible, and render the execution of 

 their function to a great extent impracticable. The direction or 

 implantation of the teeth is, at times, so far irregular and abnor- 

 mal as to change the frictional surfaces in such a manner as to 

 remove the wear and abrasion from the crown to the surface of 

 the organ. In relation to the disposition of their rubbing sur- 

 faces, it is weU known that on account of the difference existing 

 in the consistency and power of resistance, two of their elements, 

 the enamel and the dentine, their frictional surfaces become rough, 

 irregular and sAarp/ and, as they sometimes assume excessive 

 dimensions, they may give rise to serious phenomena, especially 

 when they have their seat in a part of the dental arch where no 

 resistance can be offered to their development, as when the cor- 

 responding tooth of the opposite jaws becomes diseased or absent. 



The special diseases of the elementary constituents of the teeth 

 exist in the depth of their substance, and consist in caries or ul 

 ceration of the tooth, the affection involving the dental pulp itself, 

 with other diseases pertaining to the alveolo-dental membrane, all 

 of them being accompanied by a series of weU understood symp- 

 toms, severely distinctive in their character, and which in the ma- 

 jority of cases call for the assistance of the veterinary dentist in 

 order to relieve the suffering animal from the distress in which 

 his human master knows but too well how to sympathize. 



The symptoms pertaining to the various conditions above al- 

 luded to may be either common, or general, or special. Among 

 the general symptoms, the first to be observed is a change in the 

 style of performing the function of mastication, proportional to 

 the sensitiveness occasioned by the dental lesion. Thus it is ob- 

 served that although the animal seizes his food with the same 

 avidity as if his teeth were in good order, the motion of his jaws, 

 the chewing of the food, are slowly and carefuUy performed, the 

 lateral movements of the lower jaw occurring in a hesitating man- 

 ner, and often made on one side of the mouth only. In eating 

 hay, the mouthful of the food is never triturated as it ought to 

 be, and before the process of mastication is completed the animal 

 drops it out of its mouth in the shape of a flattened bolus, satu- 

 rated with saliva, to seize it again and make a new attempt at 

 mastication, perhaps twistmg his jaw in different directions in his 



