REPULSION OF TEETH 



The identification of a given tooth often gives much difS- 

 culty to the beginner. The identification should be made 

 by passing the finger tips along the lingual or inner surface 

 of the row of teeth involved and enumerating them from 

 before backward. The line of demarcation between two 

 contiguous teeth is to be recognized by the depression be- 

 tween their necks. The student must remember that the 

 first premolar has a much greater antero-posterior, diameter 

 than the succeeding teeth. Care needs to be taken, also, 

 not to confuse the longitudinal grooves due to the plicae 

 in the dentine and enamel, especially of inferior grinders, 

 with the inter-dental depressions. 



After removing the disc of bone isolated by the trephine, 

 control all hemorrhage and then enlarge the opening and 

 remove the bony tissues till the tooth fang is, bared its entire 

 width. Insert a scalpel or bone chisel betwen the external 

 face of the bone and the soft tissues at the oral margin of 

 the trephine opening, and having 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. 

 Extend, this separation backward 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 from the zygoma only, at first 

 and then remove the plate of the ridge with the bone for- 

 ceps or chisel, after which the line into the mouth is direct 

 and the instrument can be readily pushed between the soft 



