CHAPTER XXVII.

THE COSMETIC CARE AND TREATMENT OF THE TEETH.

HAT the teeth are most useful and beautiful adjuncts of the

THA

body is self-evident. That they should be so beautiful, while subserving so utilitarian a purpose as theirs, is one of the insoluble mysteries. A young and pretty girl, inspired by affection for the love-lorn swain, beams upon him with her eyes, and he reciprocates the token with his, both adding a full view of the mills of their respective alimentary apparatus. This takes place without a thought, on the part of either, that the expression which reciprocally gladdens their hearts and irradiates their countenances has any other end and aspect than a manifestation of beauty. It is true that the whole outward appearance of the human body is seen, upon reflection, to represent usefulness underlying beauty, and, indeed, beauty conditioned upon usefulness, but no portion so flagrantly as this proclaims its subservience to the lowliest duties, while lending itself to one of the greatest charms of person.

We thank kind fortune that the modern novel is through with the chariot of Phoebus and other Olympian machinery, and simultaneously, for earth, has consigned the pearly teeth, with which heroines were always endowed, to the rubbish of oblivion. Pearly teeth have always been repellant to the eye of the connoisseur of female beauty, as indicative of fragile constitution. The two extremes of unsightliness in teeth, not decayed or crooked, are in those with the translucency of pearl or the cream-color of ivory. Between these two extremes lies beauty of color in teeth. As to their form, elongated teeth are not handsome, nor are those which are distinctively short. They both, particularly the first, indicate constitution which is not

robust. To be handsome, teeth must be fine in both form and color. With these two attributes combined in the highest degree, with immaculate purity, there is no attribute that can so much enhance the beauty of a handsome face, or better redeem the plainness of the ugliest.

The first, milk, temporary, or deciduous teeth, for they are known by all these names, are twenty in number, ten in each jaw. The permanent teeth, so-called (would that one could say so literally), are thirty-two in number, sixteen in each jaw.

Teeth are formed of enamel and dentine. There is a very thin layer of what is called cementum, around the fang, or root, of the tooth, but this is so inconsiderable that we may omit it from our present inquiry. The enamel is harder than the dentine, and lies on the crown of the tooth in nodules thinning to a layer ending in a mere film at the neck of the tooth, the place where it enters the gum. The dentine, the softer bone, called also the ivory of the tooth, surrounds the pulp-cavity, in which lies the pulp, the generatrix and preserver of the tooth in every part. Both of these kinds of bone, the enamel and the dentine, are harder than any other bones of the body, because they contain a greater percentage of bone-earth and less bonecartilage than the bones of the body do. The varying proportions of bone-cartilage to bone-earth in all the bones of the body, including the teeth, recognize the varying needs of different structures. Hardness and toughness in these substances respectively, the hardness in the bone-earth, the toughness in the bone-cartilage,-when combined in different proportions, fulfill all the varying requirements for the solid portions of the body.

The enamel contains only about 3 per cent. of bone-cartilage, the rest of it being bone-earth. The dentine, on the contrary, contains 28 per cent. of bone-cartilage and 72 per cent. of bone-earth. Compare these proportions with those of

ordinary bone. The ordinary bone of the human body, varying in composition in different parts of the body, with sex, age, health, and strength, contains, upon the average, about one-third of bone-cartilage and two-thirds of bone-earth. The bone of the teeth varies, too, with these conditions, especially with age. It is seen, however, that, speaking in general terms, the larger the proportion of bone-earth in bone, the harder the bone is, and that, on account of its largest proportion of that substance, enamel must stand first in hardness, followed by dentine. In fact, the enamel is the hardest of all organic tissues.

No matter what the kind of bone, it requires for its healthy formation nutritious and varying food. The same deficiency in these elements that, with foul air and generally unhygienic surroundings, leads to children having the cartilaginous limbs of rickets, leads also to their having stunted and defective teeth. Teeth never become otherwise than as they were nourished and grew. We have seen little children habitually set down to table to a meagre breakfast of cake and pie and preserves, with not an egg, and rarely a scrap of meat at any time; and this too where poverty did not compel, but where there was nothing standing in the way of their well-being but the densest ignorance on the part of their parents. Yet these children were expected to thrive on such pabulum. They had not the wherewithal to sustain a healthy vitality in any organ, and every detail of their bodies was impoverished and weazen. Of all miserable ways of saving, to starve the stomach is the worst. No better legacy can any father leave a child than a healthy stomach. With it the child, grown to manhood or womanhood, can front the world and dire adversity; but, without it, quails before the world as a creature of nerves to whom existence is inexorable. The ten thousand devils of dyspepsia wait on the days and nights of the richest who in early life have been denied what nature craves as the first conditions of continued vigorous life,-food plentiful and various.

The modern jaw is contracting. Such a change is strictly in accordance with present conditions of human evolution. Man was prognathous at one time; indeed is, in certain low races and individuals, even now. His canine teeth were once much larger than they are now. They were needed in his savage state as weapons, and with them he tore his ill-prepared meat-food. Civilization, through the art of cooking, renders food tempting, various, and digestible. It serves meat so that it does not require to be rent as by wild beasts. It is only ignorance that derides the art of cooking. What is vaunted often as plain cooking is nothing but confession of ignorance of the art. In proportion as it is an art, is it best fitted for the needs of civilization.

As we have seen, nature subordinates, suppresses, and in the long run discards that which is no longer of service. The fact of use and disuse, brought about by nature's compulsion to use or disuse, through natural selection, effects many changes. Dentists are right in their observation that the most modern, civilized human jaw, as compared with the jaw even within fifty years, has contracted, for the present range and phase of civilization are intensified beyond all previous experience on the globe.

Most persons think of the tooth as a solid bone. It is, on the contrary, a living structure. Not only do nerve-filaments and blood-vessels pass through the end of the roots, and thereby connect the pulp of the tooth with the general nervous system and circulation of the body, but from the pulp pass into the dentine an immense number of tubules containing filaments of soft bone-making substance, the dentine being thus injected and nourished throughout its whole mass.

The enamel is at its thickest points as much as a sixteenth of an inch through, and consists of little six-sided prisms placed side by side, and held together by some exquisitely fine cement

THE COSMETIC CARE AND TREATMENT OF THE TEETH. 337

ing substance. These standing upright, invested with a lamina of very fine bone-cuticle, naturally form a barrier to the invasion of decay, but if, through weakness of constitution or carelessness, the surface be attacked, the structure is, as its formation clearly shows, liable to rapid disintegration. Decay, having penetrated the enamel and reached the dentine, makes havoc in that relatively soft bone, the pulp of the tooth becomes diseased, and toothache may be the first sign observed of the fact that disease has reached the citadel of the tooth's life.

In the preservation of the teeth two dangers are especially to be guarded against,-the lodgment. of particles of food between the teeth, and the accumulation of tartar on them. The first of these dangers can easily be avoided by passing, nightly, and after meals, if there be time, between the teeth of both jaws a thick piece of silk thread, or even of home-spun thread, if no better kind be procurable.

The presence of tartar causes a recession of the gums. This occurs partly from the fact of the irritant composition of tartar, and partly from that of its being a foreign body impinging on the delicate edge of the gum inclosing the tooth. With some persons the chemical composition of the saliva is such that the deposition of tartar is always great, and assiduous care of the teeth is required to keep them free from it. Tartar consists chiefly of earthy phosphates. It is a complex secretion derived from three glands, and is chiefly alkaline in its chemical reaction. Klebs, a very high authority on this subject, has found with the microscope that it is full of micro-organisms, and he believes that these organisms assimilate matter in the saliva, and cast it down in the form of calcium-salts. If he be correct in this view, the fact readily accounts for the rapidity with which tartar sometimes invades the root of the tooth under the gum. When once it has begun decidedly to invade the root, the periosteum, the lining membrane of the alveole or socket of the tooth, becomes

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