THE TEETH 41 



half an inch of the rim of the orbit, and a hke distance above or in front 

 of the zygomatic ridge. If a spot be selected which is .75 of an inch 

 above the ridge, and equidistant from the orbital rim, and this spot be 

 taken as the centre of the opening to be trephined, when this part of the 

 operation is completed a punch may readily be applied over the root of 

 the sixth molar. The trephined opening is thus entirely in the malar 

 bone. The root however is not exposed, since it is covered by the thin 

 osseous plate to which reference has already been made. This plate 

 should be removed with the mallet and chisel, removing only a small 

 portion at a time, but completing the operation so that the whole of the 

 root is free. 



The operator himself should have one hand in the mouth and 

 applied to the crown of the affected tooth, or if the crown be absent, 

 the hand should be placed near the alveolus. With the other hand 

 the punch is held in position. A mallet or hammer is then taken by 

 an assistant and two or three hard, sharp taps given to the punch. 

 Particular care must be taken to hold the punch with its long axis in a 

 direct line with that of the tooth. The tooth is thus driven into the 

 mouth, and is seized and removed by the hand of the operator which is 

 in that cavity. 



When the desired effect is not attained by this method, the tooth 

 is frequently split by means of a chisel, and the fragments carefully 

 removed. 



Care must be taken, in making the cutaneous incision, not to injure 

 the orbital branch of the superior dental artery. This branch is given off 

 by the superior dental near the maxillary hiatus, and before the latter 

 vessel enters the superior dental canal. It creeps over the outer part of 

 the floor of the orbit to reach the face, down which it runs quite close 

 to the seat of operation, to anastomose with the terminal branch of the 

 angular division of the submaxillary artery. If when the flap of skin 

 has been reflected the artery is visible, it may easily be pushed forwards 

 clear of the operating area. 



