1922] on The Teeth of the Nation 489 



the best brush cannot get at many possible foci of stagnation, and 

 must be supplemented by the frequent use of antiseptic mouth 

 washes. 



Teeth, however, are not merely ornaments to be kept clean and 

 tidy. They are integral portions of the living body, and their 

 successful defiance of outer foes depends on their state of nutrition, 

 and that in turn on the nutritive state of the whole body, G-ood 

 teeth form one mark of good health, and the principal factor con- 

 cerned is proper food, not only of the adult, but more especially of 

 the child. Tooth formation begins long before birth, and the 

 healthy feeding of expectant mothers is a necessary prelude to healthy 

 offspring. Reference was here made in general terms to the 

 importance of " vitamins " and the work of Mrs. E. Mellanby on the 

 effect of withholding them on the teeth of puppies. 



In reference to diet the lecturer dwelt on the importance of 

 natural foods ; many, if not most, of patent and sophisticated foods 

 lack the essential vitamins. 



Bad teeth, on the other hand, are produced by intercurrent diseases 

 of many kinds, and the evil is not only a local one confined to the 

 mouth, or even the digestive organs, but they open the way to an 

 invasion of the whole body, and produce numerous ailments 

 (septicemic, rheumatoid, etc.). Ill-health causes bad teeth and bad 

 teeth cause ill-health, and a vicious circle is established. 



A passing reference was made to the marvel of what is called 

 Calcium Metabolism. Various animal cells are able to take up 

 soluble lime salts from the blood, and are able to deposit them as 

 solid structures which permeate the organic matrix of the skeletal 

 tissues, much as corals are capable of building their islands from the 

 lime salts dissolved in the sea. The different kinds of cells employed 

 in bone and tooth formation manifest division of labour, some being 

 able to construct enamel, others dentine or ivory, others bone, and 

 others still of reversing the building process ; the last mentioned 

 are exemplified by a certain class of cell which converts the bony 

 material of the fangs of the first set of teeth back again into a 

 soluble state, which operation terminates in the shedding of the 

 milk tooth to make room for its more permanent successor, which 

 also it should be remembered is laid down in the embryo, and so is 

 influenced by the nutritional condition of the embryo and of the 

 mother who harbours it. 



The second portion of the lecture consisted in the exhibition of 

 a series of lantern slides (Avith a running commentary) which illustrated 

 some of the main features in the various structures (enamel, dentine, 

 cement, pulp, nerves, etc.) of the fully formed tooth, and in the 

 development of the original soft dental germ into the fully formed hard 

 structure. Some slides of the closely related tissue, bone, were also 

 shown. In many cases the lecturer took the opportunity when looking 

 at healthy structures to drive home what he had previously said of the 



