114 NATURE STUDY REVIEW [8 :3— Mar., 1912 



sary to remove a milk tooth when it has outlived its usefulness, 

 either in point of time or in point of efficiency. The child has to 

 double its weight several times. He must chew much food and 

 convert it into living body tissues. Much food is also needed to 

 provide animal heat and for the large expenditure of energy on 

 the part of the healthy growing child. 



In the sum total of life the aesthetic part, of nature's string 

 of pearls is of no inconsiderable importance. The sparkle of the 

 eye and the bloom of the youthful cheek are both at at disad- 

 vantage without the solid support of a perfect set of teeth of 

 scrupulous cleanliness. 



THE TEETH AS PATHOLOGIC LEVERS. 



Ninety-seven per cent of children's mouths are found dis- 

 eased. The British Dental Association by examining 10, 517 chil- 

 dren found that the teeth in 86 per cent showed definite signs of 

 decay. There are no less than 200,000 children attending the 

 elementary schools of London whose teeth are damaged to such 

 an extent that urgent treatment is needed. Out of 10.000 chil- 

 dren examined in Strassburg, only 4.3 per cent had sound teeth. 

 Of another series of 2,269 children examined between the ages 

 of three and four, only 362 had good teeth — less than 16 per 

 cent. Of 2,103 between the ages of 6 and 8, only 74 per cent had 

 sound teeth. Of 20,000 children examined in Germany, between 

 the ages of six and sixteen, 95 per cent had dental caries to an 

 alarming extent. A carious tooth offers a break in the continuity 

 of the body — an open doorway to infection. The instances of 

 hereditary diseases, or imperfection of the teeth, are compar- 

 atively rare and would not of themselves create such a serious 

 problem as the figures above quoted indicate. Most of the dis- 

 eases of the teeth which produce so much havoc and destruction, 

 and are the source of so much pain and suft'ering. are the result 

 of our own carelessness and neglect. L'ncleanliness is the root 

 of the trouble. 



The mouth is the natural home of many varieties of bacteria : 

 there they find the proper temperature and moisture for their 

 growth, but proper temperature and moisture in themselves are 

 not sufficient to support the life and multiplication of these bac- 

 teria. An uncleanly mouth littered with food particles lodging 

 between the teeth offers them the necessary food for growth and 

 rapid multi])lication. The food particles further aid the destruc- 

 tive action of the bacteria on the teeth by their decomposition 

 and the formation of acids which injure the enamel or the outer 



