All are familiar with the toothless gums of the aged. In advanced age the teeth tend to loosen and drop out, from atrophy of the alveolar processes. This occurs sooner among civilized than among primitive peoples, owing to the insufficient use to which the teeth are put in the former case (whence results atrophy of the alveolar wall) and to the prevalence of pyorrhoea alveolaris. Complete absence of teeth must, indeed, have been practically unknown before the introduction of cookery, inasmuch as most vegetable food in the raw state needs abundant chewing, and it may therefore be regarded as certain that before the practice of cooking became common man rarely, if ever, reached the stage of edent-ulism. Long before his teeth had a chance of dropping out from senile decay, we may be sure that they were ground down to the gums (as may be observed in other vegetable-feeding animals) by the laborious chewing of dense vegetable substances, and by this time it must already have been very difficult to support life. It is probable that before the introduction of cookery the old were able to assist the work of their teeth by artificial means, such as grinding and maceration - means which, it may be remembered, are found of great service in the feeding of old horses with teeth much ground down.
In the pre-cookery period dental caries, it should here be observed, was practically unknown in man.
Then came a change. With the advent of cookery survival was no longer so closely dependent upon dental efficiency as it had been, inasmuch as cooking, by breaking up the nondigestible cellulose meshwork of the denser varieties of vegetable food, relieved the work of the teeth, and it became possible for people to survive with very inefficient teeth, or indeed, without any teeth at all. Nevertheless it is very doubtful whether in the early period of cookery - before i.e. the introduction of agriculture - life was long maintained after the teeth began to give out. Certain it is that edentulism must have been very rare in pre-agricultural times : we do not remember to have seen a single toothless jaw among the numerous skulls that we have examined of extant pre-agricultural peoples, all of whom were skilled in cookery.
When the age of agriculture was reached the supply of soft vegetable food underwent an enormous increase, especially in the late or neo-agricultural period, and this rendered man in a large degree independent of his teeth, at the same time that it promoted the tendency to disease of these organs. Sound teeth being no longer necessary to life, and the causes of dental disease having greatly increased, it is not surprising that dental disease is now so common. Long before the teeth have an opportunity of being ground down to the roots, or of falling out from sheer old age, they are, among modern peoples, but too often rendered inefficient by caries, pyorrhoea alveolaris, or other causes. So much is this the case that, were we to lose the art of preparing our vegetable food, a large proportion of the people in such a country as our own would, without the dentist's help, either have to become almost wholly carnivorous or perish from starvation.
People who have no teeth at all are often better able to masticate than those with a few only, for in the former case the gums are allowed to come together and harden, enabling them to cope with many kinds of food, whereas if the mouth is furnished with teeth, no two of which are opposed, they are useless for purposes of mastication. Sometimes, indeed, a single tooth, by preventing the gums from meeting, may render mastication impossible.
Crusts and hard biscuits may present some difficulty to the edentulous, but one which is readily overcome by soaking them in tea or coffee. The toothless should however be encouraged to retain all their starchy food in the mouth as long as possible, and to work it about, so as to mix it thoroughly with the saliva. Though a good deal of the animal food can be tackled, it is generally found advisable to mince the meat.
It has been suggested that the senile shedding of the teeth is an indication for a return to the diet of the toothless infant, and that the use of artificial teeth by the aged is apt to do harm by encouraging them to take foods unsuited to their years; but though this argument seems plausible enough prima facie, when examined critically it will be found, like so many other plausible arguments, to have no basis in fact. If senile edentulism has any biological meaning at all, it indicates, not that nature desires a return to the diet of infancy, but rather that the time has come to cease eating altogether and to lie down and die; for, as we have seen, under natural conditions edentulism implies death from starvation.
Properly fitting dentures cannot but be of advantage to the aged. Modern cookery has rendered it quite as easy for unsuitable food to be indulged in by the toothless as by others, whereas artificial teeth may be of great service by promoting the adequate mastication of the harder forms of desirable starchy foods.
The period between partial and complete edentulism may be one of considerable difficulty as regards mastication, and here the dental surgeon can be of great help : directly the teeth begin to fall out they should be replaced - one by one, if need be - by artificial ones. This is advisable not only for the purpose of maintaining masticatory efficiency, but also because in this way the mouth is enabled gradually to become adapted to the artificial dentures. If the patient waits until he has lost most or all of his teeth before resorting to artificial ones, he will have to pass through a period - perhaps a long one - of masticatory inefficiency, and in the end he may find it difficult, if not impossible, to accustom his mouth to them.