CHAPTER XXI
THE JAWS, INCLUDING THE TEETH AND GUMS

Dental caries is a process of disintegration which begins in the enamel of a tooth—usually in the region of its neck—and gradually extends through the dentine till the pulp cavity is reached.

Infection of the exposed pulp cavity may set up an acute purulent pulpitis. This is associated with severe pain, which is not confined to the diseased tooth, but may spread to adjacent teeth, and sometimes to all the branches of the trigeminal nerve on the same side of the face.

The infection may spread from the tooth to the alveolo-dental periosteum, and set up a periodontitis. In the affected tooth there is at first a feeling of uneasiness, which is relieved by the patient biting against it. Later there is severe lancinating or throbbing pain. The affected tooth usually projects beyond its neighbours, and is excessively tender when the opposing tooth comes in contact with it in mastication. The gum becomes red and swollen, and the cheek is œdematous.

Periodontitis is usually followed by the formation of an alveolar abscess. The pus, which forms at the root of the tooth, in most cases works its way through the bone and into the gum, constituting a “gum-boil.” The pus may then burst through the gum, or may spread underneath the external periosteum of the jaw and lead to necrosis.

In some cases the cheek becomes adherent to the gum and to the jaw before the abscess bursts, and the pus escapes through the skin, leaving a sinus which leads down to the defaulting tooth, and which is slow to heal, usually because there is a small sequestrum at the bottom of it. The opening of the sinus is most commonly situated at the under margin of the mandible a little in front of the masseter muscle. An alveolar abscess deeply seated in the maxilla may open into the maxillary antrum and set up suppuration in that cavity. To avoid a scar on the face, the abscess should be opened from the mouth. A periodontal abscess of one of the upper central incisors spreads backwards between the muco-periosteum and the bony palate, causing an elongated swelling in the roof of the mouth.

In all cases the extraction of the carious tooth is necessary before the abscess will cease discharging and the sinus heal. If a sequestrum is present it must be removed, and the bone scraped with a sharp spoon. Among the other effects of dental caries may be mentioned localised necrosis of the alveolar margin, cellulitis of the neck, and enlargement of the cervical lymph glands.

A cyst is frequently found attached to the root of a decayed tooth. It is lined with epithelium, and is probably derived from a belated portion of the enamel organ which has been stimulated to active growth by infective processes in the pulp cavity. It is seldom larger than a pea, and contains a pultaceous mass like inspissated pus. It gives rise to no symptoms, and is only recognised after extraction of the root.

Odontomas have already been described (Volume I., p. 192).