This section is from the book "Dental Medicine. A Manual Of Dental Materia Medica And Therapeutics", by Ferdinand J. S. Gorgas. Also available from Amazon: Dental Medicine.
Alveolar Abscess about to point Externally is indicated by the skin, for some distance around the central point, becoming red and distended, with a throbbing sensation, succeeded by a change in the appearance of the skin to a thin and scaly surface, from which the epidermis scales off. The integument becomes glued down to the bone around the spot where the pus will ultimately appear; the latter following a fistulous track between the diseased tooth and the surface of the cheek, the fistula remaining open and discharging as long as the inflammatory action continues.
Make a free incision in the gum opposite and near the apex of the root of the affected tooth. Apply to the surface of the threatened point of exit of the pus, alcohol, or spirits of camphor, or paint with collodion, and make gentle pressure by means of a compress of sheet lead or sheet tin, or pads and bandage, to change the direction of the pus.