The cause and prevention of decay in teeth : an investigation into the causes of the prevalence of dental caries ; to which are appended some suggestions on its prevention / by J. Sim Wallace.

  • Wallace, J. Sim (James Sim), 1869-1951.
Date:
1902
Catalogue details

Licence: Public Domain Mark

Credit: The cause and prevention of decay in teeth : an investigation into the causes of the prevalence of dental caries ; to which are appended some suggestions on its prevention / by J. Sim Wallace. Source: Wellcome Collection.

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    fined to what is shown externally. In the case of man, however, even though a small-jawed individual may be presumed to be more beautiful and, ceteris paribus, more liable to be preserved and have offspring, equally, however, are small teeth regarded as beautiful, and might be sup- posed to be equal factors in sexual selection. ‘T his subject will be referred to more fully in chap. v. The relative sizes of the teeth and jaws have little to do with esthetic considerations, and indeed the wisdom tooth has diminished in size much more quickly than has the jaw. The principal reason for the want of growth of the jaw is the fact that it is not sufficiently used, and does not develop to its normal size. The crowns of teeth, however, being fully formed as regards size beneath the gum before they are functionally active, the size of the teeth is inde- pendent of the amount of use they are put to by the individual. Hence a quick transition from coarse food to soft food in one generation brings about a crowded and irregular set of teeth, and an accompanying amount of dental caries. The cause of the smallness of the jaws compared with the teeth may easily be shown to be due to the non-development of the jaw-bone through lack of the proper amount of work being thrown upon it and the tongue. The exceedingly bad results of feeding children on soft foods after they have got their temporary teeth may be indicated by tracing what happens as a rule in these circumstances. A child gets its temporary teeth, and assuming even that they are not decayed, the teeth of the permanent set replace the incisors, then the bicuspids