ON LATERAL PRESSURE. 171 



the premature removal of a tooth ; and although 

 desirable not to sacrifice a temporary tooth need- 

 lessly, there can be no worse evil resulting from 

 it; and beyond the removal of an aching tooth, 

 perhaps, this form of mouth seldom needs the 

 interference of the dentist, and certainly not on 

 account of irregularity. 



These peculiarities of the oral cavity are strongly 

 marked at an early age — long before that period 

 in the stage of dentition which usually commands 

 the notice of the dentist, — and afford an unerring 

 prognosis for our guidance in the treatment of 

 the growing mouth. They have been made the 

 basis of my own practice in this respect for many 

 years past, and I can assert with confidence that 

 I have never been once disappointed in any of its 

 anticipated results. 



At a later period, however, but often before 

 the dentine has arrived at completion, other 

 results begin to arise. The pressure from the 

 cheeks, which in Fig. 17 had no share in the ar- 

 rangement of the teeth, now begins to show its 

 effects in a different form. Force applied upon 

 the outer curve of an arch, causes a thrust against 

 its buttresses, but at the same time has a crushing 

 tendency upon the sides of each of its component 

 parts (if it be constructed in several portions), 

 through the tendency of the curve to become 

 flattened. Thus, the tension of the muscles upon 

 the outer curve of the dental arch, produces a 



