VETERINARY DENTAL SURGERT. 239 



large variety of these in the market, Dr. E. A. A. 

 Grange's, being probably the best, Fig. 61. In 

 drilling out the cavities in the molars we have to de- 

 pend almost exclusively on the dental engine, as the 

 hand drills cannot be used in the mouth. The hand 

 piece referred to before Fig. 56, operating at right 

 angles, or Fig. 57 operating at an acute angle, are 

 the only instruments with which cavities back of the 

 first molar can be made. In preparing the cavities 

 great care should be taken to obtain suitable retaining 

 points; in the molars we can leave the cavity larger 

 at the bottom than at the orifice, dove-tailing it as it 

 were. This form retains the filling well, but great 

 care must be exercised in filling, to have it pressed 

 firmly against the walls of the cavity so as to support 

 them, otherwise they will be crushed in. 



