The physiology of digestion, considered with relation to the principles of dietetics / by Andrew Combe.

  • Andrew Combe
Date:
1860
Catalogue details

Licence: Public Domain Mark

Credit: The physiology of digestion, considered with relation to the principles of dietetics / by Andrew Combe. Source: Wellcome Collection.

    41/224 (page 17)
    makes us instantly aware of the con- tact of bodies either too hot or too cold. When diseased, the ordinary sensibility of the nerve is often so far increased as to become converted into the racking pain of toothacli. To prevent the teeth from being worn down by friction, their visible part or crown is covered with a very hard white ivory-looking substance, called enamel, into which neither blood- vessels nor nerves have been observed to penetrate. Owing to this structure, the teeth can be safely exposed, on all proper occasions, without sustaining damage—a privilege on which most persons will be disposed to place a higher value, after having experienced the pains consequent upon injury of the nerve from a portion of the ena- mel being broken off. An obvious advantage attending the vitality of the teeth is, that it enables them to accommodate themselves to the growth of the jaw and general system at the different periods of life. In^ early infancy, when the human being is designed to live exclusively on its mother's milk, for the disposal of which no teeth are required, the latter are still imperfectly formed, and entirely hidden in the jaw : it is only at the end of some months that the front or cutting teeth begin to ap- pear ; and the whole set of milk, deci- duous, or falling-out teeth, twenty in number, is not completed till about or after the third year. In the course of three or four years more, however, growth has advanced so far that the first set of teeth no longer fill the jaw; and they soon begin to be displaced by the second or permanent set, the Gra- dual development of which commences at that period of life, and is not finished till the appearance of the last four grinders or wisdom-teeth, about the age of maturity. The teeth, being living parts, and at the same time endowed with a me- chanical function, are liable to injury in both capacities. Being composed chiefly of earthy matter, such as phos- phate and carbonate of lime, the con- tact of strong acids decomposes or de- stroys their substance, and leads to their rapid decay. Hence, the white- ness produced by acid tooth-powders and washes is not less deceitful than ruinous in its consequences ; and hence, also, great caution is necessary never to allow the acid drops frequently pre- scribed by physicians to come into con- tact with the teeth. The teeth, being constantly mois- tened with saliva, have a tendency to become incrusted with the tartar or earthy matter which it contains in so- lution, and which is separated from it partly by the evaporation of the more fluid constituents while breathing, and partly by chemical decomposition. As this incrustation not only destroys the beauty of the teeth, but also hastens their decay, it ought to be carefully removed as soon as formed; and the most effectual mode of doing so is to brush the teeth regularly twice a-day —especially in the morning, when the quantity is greatest—with a brush dip- ped in soft water—till every particle is removed. The addition of any soft impalpable powder will assist in the effect; but nothing capable of acting chemically on the teeth, or of injuring them by friction, ought ever to be re- sorted to. Washing the mouth after every meal is also a good preservative. When a long time elapses without eating, and also when digestion is im- paired, the quantity of tartar which accumulates on the teeth is very great. •Hence they are always most incrusted in the morning, and during fevers and other affections when little or no food is taken. I have seen one instance in which a thick coat of tartar was re- moved by a dentist, in the belief that it was a diseased tooth—the tooth it- self on which it was formed being left in the jaw perfectly sound. When the tartar is not duly re- moved, its presence injures the teeth, irritates the gums, and generally leads, sooner or later, to considerable suflTer- ing. The regular washing and brush- ing above mentioned ought, therefore, to be sedulously practised at every pe- riod of life, and taught as a duty to the young. When digestion is very vigorous, the health good, and the diet plain and containing a full proportion