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i UNIVERSITY 7 ) 

 ERUPTION OF THE TEETH. 193 



rami has been going on slowly, but without interruption. 

 Thus is brought about a condition of parts allowing of 

 the whole series of teeth coming into their proper mutual 

 antagonism. 



It was pointed out by Trousseau that the eruption of the 

 teeth is not a continuous process, which, once commenced, is 

 carried on without intermission to its completion, but that it 

 is interrupted by periods of repose. The teeth are, according 

 to his statement, cut in groups ; the eruption of the teeth of 

 each group being rapid, and being succeeded by a complete 

 cessation of the process. Individual variations are nume- 

 rous ; the following may be taken as an approximation to 

 the truth : 



The lower centrals are erupted at an age ranging from six 

 to nine months ; their eruption is rapid, and is completed in 

 ten days or thereabouts ; then follows a rest of two or three 

 months. 



Next come the four upper incisors ; a rest of a few 

 months ; the lower laterals and the four first molars \ then 

 a rest of four or five months. 



The canines are peculiar in being the only teeth of the 

 temporary set which come down between teeth already in 

 place. To this, as well as to the greater length of their 

 root (though it is not quite clear what this has to do with 

 it), Trousseau ascribes the great length of time which their 

 eruption occupies, it taking two or three months for its com- 

 pletion. According to him, children suffer more severely 

 from constitutional disturbance during the cutting of these 

 teeth than that of any other, but Dr. West thinks that the 

 eruption of the first molars causes the most suffering. It 

 may also be noted that the canines during their develop- 

 ment lie farther from the alveolar border than do the other 

 teeth, so that they travel a greater distance ; obviously, not 

 merely from the elongation of the root, which is wholly 

 inadequate to effect such a change in position. 



