The incisores, or fore teeth, are eight in number, four in the front of each jaw-bone. These generally appear first, though seldom till seven, eight, or ten months. Some few infants have been born with teeth so sharp as to cut their nurse's nipple. The original substance of the teeth is lodged in sockets, and covered by the gums, to the bottom of which it extends its roots, and pressing forward by little and little, at length forces its way through them. Though this operation is natural, it is not, however, consonant to the general laws of Nature, which constantly operate upon the human body, without exciting any painful sensation. Here Nature makes a violent and an excruciating effort, which is sometimes attended with fatal consequences. In breeding their teeth children lose their sprightliness, and become peevish and restless. The gums are at first red and swelled, and afterwards, when the pressure is ready to intercept the course of the blood in the veins, they appear white. They are constantly applying their fingers to the affected part as if endeavouring to assuage its irritation: they obtain further relief by putting into their mouth a bit of ivory, coral, or any other hard and polished substance they are supplied with, which they rub on that part of the gums that is most affected. This action relaxes the parts, and affords a momentary cessation of the pain; it also helps to attenuate the membrane of the gum, which, from the double pressure it then sustains, must break the more easily; yet this laceration, or rupture of the gums, is frequently attended with no small degree of pain and danger. When the gums are more firm than usual, by the solidity of the fibres of which they are composed, their resistance to the action of the tooth is more obstinate, and occasions an inflammation, with all its deadly symptoms. In order to preclude this, an incision may be successfully made on the gum, by means of which minute operation the inflammation ceases, and the teeth obtain a free passage.
The canine, or dog teeth, which are next to the incisores, are in number four, and commonly appear in the ninth or tenth month. About the end of the first, or in the course of the second year, sixteen other teeth appear, which are called molares, or grinders, four of which are situated on each side of the dog teeth. The periods for the cutting of the teeth vary in different children, and though it is pretended that those of the upper jaw usually appear first, yet it often happens that they are preceded by those of the under.