PROBLEMS OF HUMAN DENTITION 123 



After this statement we shall try to solve the question as to 

 the place occupied by the paraniolars in our dental system. The 

 principal point to reckon with in outlining such a system un- 

 doubtedly is furnished by the fact that the paramolars alternate 

 with the molars, the Paramolar I with the first and second, the 

 Paramolar II with the second and third. In a clear manner this 

 fundamental i)oint is expressed by the following simple scheme 

 in which the paramolars are represented by the symbol Pa, the 

 molars by Mo. 



Pa I. Pa 11. 



Mo. 1. Mo. 2. Mo. 3. 



This scheme recalls at once the topographical relationship 

 between the elements of the first and second dentition. For 

 these are also placed in two rows, an outer and an inner. The 

 teeth of the inner row, i.e., of the second dentition, develop 

 lingually from those of the milk dentition, and moreover their 

 topographical relation is such that the permanent teeth alter- 

 nate with those of the milk dentition. So the first permanent 

 incisor alternates with the first and second milk incisor, the 

 second permanent incisor with the second incisor and the canine 

 of the milk dentition, etc. A milk tooth consequently is suc- 

 ceeded by a tooth originally situated disto lingually from it. 

 In the farther progressed phase of development of our dentition, 

 this primitive topographical condition is disturbed, so that for 

 instance the canine frequently erupts at the outer side of its milk 

 predecessor. 



In the next scheme a simple representation is given of the 

 original relation between the elements of our first dentition, 

 and the corresponding ones of the second. 



ii io c nil ni2 

 Ii I2 C Pi P2 



A comparison of this scheme with that of the molars and i:»ara- 

 molars, immediately reveals the agreement of the two with each 

 other, the paramolars being situated with regard to the molars, 

 just as the milk teeth are with regard to the permanent teeth. 



THE AMERICAN JOURNAL OF ANATOMY, VOL. 19, NO. 1 



