Keeping The Teeth In Good Condition
( Originally Published 1920 )
The Uses of the Teeth.—Do you know what kind of teeth a dog or a cat has, and how they differ from the teeth of a cow or a horse?
The teeth of the dog and the cat are sharply pointed, so that they can be used for tearing and cutting. The teeth of the horse are flat and are made for grinding things into a pulp. In each case the teeth are of just the kind needed to work on the kind of food the animal eats. A dog lives chiefly on animal food, such as meat, which must be torn into shreds before it is swallowed. The horse, on the other hand, lives on oats, hay, and similar foods that do not need to be torn up, but must be ground into a fine pulp. We can generally tell what kind of food any animal eats by merely looking at its teeth.
Which kind of teeth do you have in your mouth? Look in the mirror, or pass your tongue over them, and you will see (or feel) that you have both kinds. This is just what might be expected, since you eat both animal foods and vegetable foods, like bread and cereals. In the front of your mouth are cutting teeth, not just like the pointed teeth of the dog, but having a long sharp edge which serves the same purpose; while at the back are flat teeth for grinding, which do the same sort of work as the teeth of the horse.
The teeth form a very important part of the digestive system, for unless the food is well broken up and mixed with the digestive juices of the mouth, it will reach the stomach in lumps and will be very hard to digest.
The First and Second Sets of Teeth.—There is one very curious thing about the teeth—and that is the fact that we have, each of us, two distinct sets of teeth, one for there down below the surface, though very small. Soon they begin to grow and push out through the gums. By the time a baby is two years old, it usually has all its first set of teeth—twenty of them—and these are the teeth a child uses till it is more than five years old.
At about the age of six years, the first teeth begin to loosen and come out; and soon after each one of the first set drops out, one or more of the second or permanent set of teeth grows in its place. There are thirty-two of these permanent teeth, and most of them grow out between the ages of six and twelve. The last four teeth sometimes appear when a person is twenty years old or more. They are called the "wisdom teeth," because when one gets to be as old as twenty, one ought to be quite wise.
The Parts of the Tooth.—The part of the tooth that we see in the mouth is squarish or flattened, according to the kind, and is called the crown. It is covered with a very hard smooth substance, called enamel. Beneath the surfaces of the gum are the roots, which are pointed ends, one, two, or three to each tooth. The roots hold the teeth in place, somewhat as a root holds a plant Root firmly in the ground. The crown of the tooth is mostly hard dead matter, but in the roots there are nerves and other kinds of living tissue.
The Value of Good Teeth.—A straight, clean, shining set of teeth is always pleasant to look at. It is also a help in keeping the whole body in good health. If the teeth are strong and sound, their work of preparing the food for digestion by thorough chewing is much more likely to be well done. When people grow old, the teeth often fall out and have to be replaced by false ones. The better care we take of our teeth, the longer we shall keep the ones that Nature gives us.
The Microbes and Tooth Decay.—The teeth seem so hard and strong that you might think they were the very last parts of the body likely to become diseased.
Yet, curiously enough, there are very few organs that give us so much trouble as our teeth.
Diseases of the teeth are usually caused by very tiny plants or animals called microbes, a word which means a little living thing. We shall learn more about microbes in Chapter XIV. They are very small indeed, so small that thousands of them could be on the point of a pin without your being able to see anything there at all, even with your sharp eyes. The microbes can be seen, however, with a special instrument called a microscope. You probably know what a magnifying glass is and how, by looking through it, you can see small things that would be quite invisible with the eye alone. A microscope is a very powerful magnifying glass; and by looking through such a glass at one of the bits of food left clinging between the teeth, you could see great numbers of microbes, such as are pictured on page 162.
In the food particles, these microbes grow and in-crease in numbers very rapidly. As they grow, they change the food and spoil it, so that it smells badly. The destruction of food or other substances by microbes is called decay. Some of the microbes that grow in food masses on the teeth form chemical poisons, which eat into and decay the hard enamel of the teeth them-selves. In the little cavities that are produced in the teeth, more food gathers, and more microbes grow, and more chemical poisons are formed. These substances eat into the tooth deeper and deeper, until finally the poisons formed by the microbes, and perhaps even the microbes themselves, reach the living tissue inside the tooth.
It is unpleasant to think of having such things as this going on inside your mouth, and the results are quite as unpleasant as you might expect. Bad teeth often give the month a very disagreeable odor, even when the decay has only just begun. As the process goes on, the teeth become sensitive, and chewing is neglected, which of course is bad for the digestion. When decay reaches a certain point, real toothache begins, as a result of the work of the poisons formed by the microbes. If you have had a toothache, you know how painful it is; and if you have not, I hope you may never learn. Even the toothache is not always the worst of it. Sometimes the microbes get into the soft tissue at the root of the tooth, and the poisons which they form are carried by the blood all over the body. Or the microbes themselves may pass through the blood to the heart or some other organ. If this happens, serious and even fatal disease may follow. Microbes may often be present in the mouth or intestines without doing serious harm; but if they grow inside the tissues of the body, they always cause illness. So you see that tooth decay may really be a very dangerous thing, and we ought to guard against it with every possible care.
Guarding against Tooth Decay.—The chewing of ordinary tough foods is good for the teeth. Vigorous use polishes their surfaces and keeps the muscles that move them in active condition. We should not, how-ever, crack nuts or bite very hard objects, for that may chip off the enamel.
The most important precaution we can take against the dangers of tooth decay is the regular use of the toothbrush. If the teeth are kept thoroughly clean, the microbes will never get a chance even to start their evil work.
The, best possible thing to do is to brush the teeth carefully after each meal, so as to remove any bits of food just as soon as they have collected. If we cannot always do this, we should brush the teeth at least twice a day, night and morning. The brush should be stiff, but not too hard. It should be applied systematically, not only to the flat tops of the teeth but to the fronts and backs as well.
Some people brush their teeth along the sides from the back to the front of the mouth, and some brush up and down, from the gums to the crowns of the teeth.
The best way of all is to hold the brush in the position shown in Fig. 44, press the bristles firmly against the teeth, and give the brush a slightly rotary (round and round) motion. When the outside surfaces at each side and in front have been well cleaned, the inner surfaces should be treated in thé same way. Then the crowns of the teeth should be brushed thoroughly.
Finally, after the brushing has been completed, the mouth should be rinsed several times. You will find that you can do this by forcing water between and around the teeth with the aid of the lips and tongue.
The Brushes' Quarrel.-Once upon a time a little girl thought she was waked up one night by a noise of voices in the kitchen. It seemed to her that she pushed the kitchen door open softly and that this was what she saw and heard.
The moonlight was shining quite brightly through the kitchen window, and sitting in a ring on the floor were all the brushes and brooms in the house. They were having a vigorous argument as to which one ought to be king. The broom was presiding at the meeting, because he was biggest; but it had been agreed that the one that was most useful in the household ought to be the king, and each was presenting arguments why he should be the one.
The hearthbrush declared that ashes from the fire-place made more dirt in the house than everything else put together, and that his work of keeping them back on the hearth and preventing them from being blown about was the most important thing a brush could possibly do.
Mr. Broom, the chairman, put in his word. "There is nothing at all in the Hon. Mr. Hearthbrush's claim." (The broom was always very formal and polite.) "The open fires are only lighted in certain rooms and at certain times; but there is dirt in the house always and everywhere. I am the one who has to keep it clean from attic to cellar, in July as well as in January, and my work is therefore most important of all."
The bottle brush and the sink brush applauded this (by rubbing their bristles against each other) ; but the clothesbrush jumped into the center of the circle, very much excited, and gave the discussion a some-what new direction. "It is true that Temporary Chairman Broom probably moves more dirt in a year than all the rest of us put toether," he said, "but I claim it is quality of work, not quantity, that ought to count. Mr. Broom is trusted for the heavy work of cleaning floors and stairways, but when they want a really good job done, when they want the clothes they wear to be spic-and-span, they call on me."
"There is a great deal in what Brother Clothesbrush has said," interrupted a handsome silver-mounted hair-brush, "but his argument counts much more for me than it does for himself. The clothes are more important than the carpets, but the head is more important than the clothes, and I have by far the greatest work of all to do."
There was silence for a moment, and it almost looked as if the hairbrush would carry the day. Suddenly a tiny little figure ran out into the moonlight, and a high squeaky voice cried out, "Wait a bit, wait a bit, until you have heard a plea from me, the Toothbrush. The clothes are more important than the carpet, and the head than the clothes, I agree. But the inside of the head is far more important than the outside."
"If Mr. Clothes Brush or Mr. Hairbrush is neglected," he went on, "our masters and mistresses will look untidy, but they will not get ill; while if I were not used, there would be toothache and misery and illness as a result. I am the one who ought to be king of the brushes."
There was a great hubbub and noise, some taking .little Mr. Toothbrush's side and some opposing him; but just then the dreamer woke up and never knew who was finally chosen king.
The Dental Care of the Teeth.—The toothbrush is certainly one of our best friends, but even the regular use of the toothbrush cannot be expected to defend the teeth completely from our microbe foes. Every now and then decay begins on a small scale, even in well-cared-for mouths. It is important that the teeth should be regularly examined by a dentist in order to detect this decay and treat it before it has gone too far. If the teeth are examined two or three times a year, they can be kept sound very easily and with no pain. The dentist can also straighten teeth that are crooked, which of ten improves a child's looks and his health very greatly. Early and frequent dental care before the teeth decay will spare many painful hours afterward. It is for this reason that most schools provide for the systematic examination of the teeth of the children, and there are few things that the school doctor and the school nurse do which are more important than this.