174 ON LATERAL PRESSURE. 



connected with dentition generally, I am more 

 disposed to attribute it to the above cause. The 

 first molar is in some respects analogous to the 

 dens sajpientice ; it stands in pretty much the same 

 relation to the deciduous teeth that the wisdom- 

 tooth does to the first and second molars ; and 

 we know how very generally the wisdom-teeth, 

 when cut late, or even at the accustomed age, are 

 soft, friable, and rapidly decaying, but which is 

 not the case when the early removal of one of the 

 molars has caused it to make its appearance within 

 a short time afterwards. Its more rapid growth, 

 and the absence of any particular pressure from 

 confinement within its cell, by the other molars 

 coming forward, and thus enabling it to effect its 

 own liberation, are correlative with its being a 

 healthy and well-formed tooth ; therefore, there 

 is some reason to suppose that its being in an 

 imperfect state is the result of pressure during its 

 protracted formation, and that the first molar may 

 be similarly affected. 



In the correction of irregularity by the expan- 

 sion of the arch (and which is extremely easy by 

 pressure applied within the arch), it becomes a 

 question how far this extension can be carried 

 with safety ; for if the teeth be placed much within 

 the influence of lateral pressure from the action of 

 the muscles of the face, we run great risk in 

 having them made to decay. The amount of it 

 must therefore be guided by circumstances ; for 



