Diseases of the Teeth.—Decay (caries) is by far the most common of the diseases which affect the teeth, and consists in a gradual and progressive disintegration of the tooth substance. The exciting cause of caries has been proved to be due to the action of micro-organisms producing lactic acid.
Decay is rarely met with on smooth surfaces exposed to the friction of food and the direct washings of the saliva. It usually begins in some pit or groove in the enamel or between the teeth, such points forming a lodgment for the de velopment of the organisms. Once the enamel has been penetrated the decay proceeds more rapidly, spreading later ally beneath the as yet healthy enamel and toward the pulp. Caries is most common in early life, by far the greater number of cavities making their appear ance between the ages of 6 and 18. Pain may be felt soon after the enamel has been penetrated, or may be delayed until the nerve (pulp) has become almost or quite exposed. Ultimately the pulp be comes exposed when the pain increases and may become very violent, especially if the nerve be pressed on by food forced into the cavity by mastication. Should this take place the pulp becomes acutely inflamed and soon dies, when the pain may either cease or go on till an alveolar abscess is formed.
Periostitis and Alveolar Abscess.—Per iostitis is an inflammation of the mem brane (periosteum) which covers the roots of the teeth and lines their sockets. It may be either general or local. When general the majority of all of the teeth are commonly involved. When the disease is local—confined to one or two teeth— it may result from a blow or some such injury, or it may proceed from an in flamed pulp; but by far the most common cause is the presence of a dead nerve, the poisonous products of which are liable at any time to cause violent inflammation at the end of the root.
Alveolar abscess may be defined as a suppuration around the root or roots of a tooth. It is of two varieties, acute and chronic. Its causes are those of peri ostitis, which precedes it, the continuous and throbbing nature of the pain indicat ing the formation of matter (pus) within the surrounding bone.
Exostosis is characterized by an in crease in the thickness of the cementum, the external of the two hard tissues forming the roots of the teeth. Its forms vary from a small nodule or patch to a quantity sufficient to invest the entire root or roots of the same or adjoining teeth. Exostosis may often cause neu ralgic pains about the jaws.
Impaction and Difficult Eruption of the Wisdom and other Teeth.—lt is not uncommon to find certain of the tem porary teeth firmly set in the adult jaw, and occupying the place of the perma nent ones. In such cases the permanent tooth is usually present in the body of the jaw, but it has been retarded in eruption by being too deeply imbedded in the bone. Impaction may also be due to an abnormal direction of growth. Such teeth may appear late in life after all the others are lost, and the bone overlying them has been absorbed and so exposed them. When these cases do occur they are responsible for the popu lar but incorrect idea of a third set of teeth. An impacted tooth seldom gives rise to any trouble, unless it be an upper or lower wisdom, particularly the latter. The cutting of these teeth is sometimes accompanied by distressing symptoms which may be protracted for months or years, unless they are removed by ex traction of the tooth.
Absorption of the Alveoli.—The grad ual wasting of the bone which surrounds and supports the roots of the teeth, accompanied by a simultaneous recession of the gums, is one of the changes which mark the approach of old age. This wasting may, however, occur in middle life without any visible cause, though the majority of such cases are due to chronic inflammation of the gums, with or with out the deposition of tartar. Heredity, or the use of too hard a tooth brush, may likewise be accountable. The teeth most affected are the front ones; but the re verse of this is not unusual. The gums, especially in front, gradually recede and lay bare the roots; the teeth now become loosened and finally drop out.
Toothache is not so much a disease as a symptom. Its chief causes are men tioned under caries and alveolar abscess. When toothache is due to caries with or without simple exposure of the pulp, the attack is brought on by taking hot or cold, sweet or acid fluids, and is seldom of long duration. To afford relief in such cases as these, gently wash out the cavity with a solution of carbonate of soda; then, drying it carefully with a piece of cotton-wool, take a very small pellet of wool dipped in eucalyptus oil and place it in the bottom of the cavity; over this place a piece of cotton wool large enough to fill the cavity and satu rated with the following solution: 1 drachm of mastic in 14 ounce of eau de cologne. This should be changed daily. When the pain is caused by the forming of an alveolar abscess the tooth will be found insensitive to change of tem perature but very susceptible to pressure. The patient now becomes feverish, and the pain, which is at first of a dull heavy character, becomes more intense, throbbing, and continuous, till pus has been formed and discharged through the gum. Provided the tooth is likely to prove useful and the patient cannot con sult a dentist, the gum should be care fully painted with tincture of iodine, or the old-fashioned plan of placing a roasted fig over the root may be resorted to; at the same time it is well to give an aperient such as epsom salts, followed by a full dose of quinine-6 to 8 grains for an adult. Great reliief follows this treatment, wihch is, of course, only tem porary.
Hygienic Care of the Teeth.—Many of the diseases of the teeth and gums might be prevented or greatly retarded by proper attention to the cleansing of these organs. The implements best fitted for this purpose comprise the quill tooth pick, waxed silk thread and brushes, with suitable powders. An excellent tooth powder is composed of precipitated chalk, 2 ounces; light magnesia, 2 ounces; oil of cinnamon, 8 drops; thymol crystals, 4 grains; otto of roses, 10 drops. The teeth should be brushed twice daily, in the morning and in the evening. The brush, used properly, should be pressed against the teeth and the handle rotated so as to make the bristles sweep ver tically between and over them; this, cou pled with an up-and-down motion, will thoroughly cleanse the interspaces; the inner surfaces of the back teeth are best cleaned in a like manner, while the cor responding parts of the upper and lower incisors are effectually reached by a vertical drawing movement. The brush should be of medium texture, and the bristles of unequal length, and not too closely placed.