REPULSION OF TEETH. 9 



trephine according to the method described in the following 

 chapter down through the alveolar plate immediately over 

 the fang of the affected tooth. Avoid dulling the trephine 

 by striking it against the tooth fang itself. If an external 

 fistula exists the identity of the affected tooth is best 

 determined by passing a metallic probe through it against 

 the diseased fang while one hand is passed into the mouth 

 and the location of the probe more fully ascertained. Care 

 should be exercised in trephining to not injure the adjoining 

 teeth. After removing the disc of bone isolated by the 

 trephine, control all hemorrhage and then enlarge the open- 

 ing and remove the bony tissues till the tooth_fang_isJbared 

 its entire width. Insert a scalpel or bone chisel between the 

 bone and soft tissues at the margin of the trephine opening 

 nearest the mouth and with one hand in the oral cavity 

 with the fingers resting upon the alveolar border on the 

 lateral side of the tooth to serve as a guide, push the 

 scalpel or chisel along between the bone and soft tissues 

 until it emerges from the gums alongside the affected tooth 

 and extend this separation backwards and forwards until 

 the soft tissues are completely detached from the alveolar 

 wall over the entire area of the diseased member. When 

 operating upon the superior molars the fangs of which are , 

 covered by the zygomatic ridge, the chisel or scapel cannot 

 be pushed directly from the trephine opening into the mouth 

 between the soft tissues and the bone because the line is 

 concave instead of direct. In these cases it is best to 

 detach the soft parts only from the zygoma at first and then 

 remove the alveolar plate of the ridge, after which the line 

 into the mouth is direct and the instrument can then be 

 readily pushed between the soft and osseous tissues for the 

 remainder of the distance and the separation completed. 



In operating upon the inferior molars covered by the 

 masseter an opening may be made near its lower border 

 large enough to admit the trephine or the muscle may be 



