CHAPTER XV. 



DISEASES OF THE LOWER JAW INJURIES FROM 

 HEAVY CURB BIT. 



Disease of the lower jaw sometimes exists which 

 calls for the use of the trephine; such as carious 

 teeth, necrosed bone and superficial fractures where 

 a small portion of bone has been partially or com- 

 pletely separated by external violence. 



In using the trephine on the lower jaw great 

 care must be exercised, for the bone here is thin, 

 hard and easily fractured. If the opening by the 

 trephine is made in the lower border of the jaw a 

 five-eighths trephine is as large as should be used. 

 If the opening is made on the side a larger instru- 

 ment may be employed with safety. 



To remove the first, second, third, fourth and 

 sometimes fifth lower molars, the opening for that 

 purpose will be more convenient if made directly 

 under the roots of the tooth. For the sixth and 

 sometimes the fifth the opening should be made into 

 the side opposite the end of the fang of the tooth. 

 It can then be readily driven out with the curved 

 punch in Fig. 51. In trephining for the fourth, 

 fifth and sixth lower molars the opening should not 

 be made indiscriminately. Care must be taken not 



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