REPULSION OF TEETH. 13 



best to detach the soft parts from the zygoma onl}' at first 

 and then remove the alveolar plate of the ridge with the 

 bone forceps or chisel,, after which the line into the mouth 

 is direct and the instrument can then be readily pushed be- 

 tween 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 through the muscle may be made near 

 its lower border large enough to admit the trephine or the 

 muscle may be detached at its point of insertion to the 

 inferior maxillary bone and two parallel incisions carried 

 upwards a short distance, permitting the raising of a flap, 

 or what is generally best for the second and third molars, a 

 curved incision is made at the antero-inferior border of the 

 masseter muscle parallel to the parotid duct and satellite 

 vessels and just posterior to them and the muscle lifted up 

 and drawn backwards sufficiently to expose the bone im- 

 mediatel}^ over the tooth fang. 



With a light, narrow bone chisel cut away and remove 

 the external alveolar plate over the entire extent of the 

 tooth, from the oral margin of the trephine opening into- 

 the mouth cavity. Hold the chisel so that the outer edge is 

 inclined from the affected tooth toward the adjoining one, 

 thus making a bevelled channel through the alveolar plate 

 tending to loosen the isolated section of bone by driving it 

 outwards. Drive the chisel for a short distance on one 

 side, then upon the other, and thus break the alveolar plate 

 away in small sections and avoid an extension of the 

 fracture to neighboring alveoli and damage to adjacent 

 teeth. Care should be taken that the bone chisel is sharp 

 otherwise extensive fractures of the bone may occur. With 

 gouge and chisel remove all remnants of bone over the 

 lateral side of the tooth lajdng it completely bare as shown 

 in Plate II. 



The soft tissues of the part should not be disturbed 

 beyond the excision of the circular piece, corresponding to- 



