168 ON LATERAL PRESSUEE. 



hesitation in saying it would never reach its in- 

 tended destination without assistance. And also, 

 that were the tongue and the lower lip to be pre- 

 vented from touching the lower incisors, these 

 would never assume that degree of regularity 

 which they are usually found to do after such 

 operation. An incisor within the arch in the 

 lower, is always much sooner restored to its 

 proper position than an outlying one ; and it is 

 this force, the pressure of the tongue, which, as 

 the permanent incisors come up behind their tem- 

 porary predecessors, pushes them forward into 

 their places. 



In cases of crowded dentures, it is well known 

 that the greatest amount of irregularity almost 

 invariably occurs at the angles of the mouth, in 

 the neighbourhood of the bicuspids, and it is just 

 at this part that the pressure of the muscles of 

 the face is exerted with its greatest force. If the 

 mouth be distended to its utmost, a considerable 

 amount of pressure will be felt upon the teeth in 

 this region, from the tension of the m'bicularis oris 

 and anterior portions of the buccinator connected 

 with it. If the palate be broad and shallow, the 

 more frequent action will have the preponderance, 

 and the teeth will have becorae arranged . at the 

 sides and extremity of the tongue when at its 

 greatest point of expansion ; and the exterior 

 pressure will then only have the effect of crushing 

 the teeth together, and causing them to decay. 



