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.
Dislocation of the Lower jaw, when double, is indicated by inability to close the mouth; the mouth widely open ; the chin prominent, with a distinct hollow in front of each ear. A single dislocation is indicated by the mouth being only partially open, the chin displaced to one side, the distinct hollow below the ear being on the opposite side.
Reduction is made by placing the thumbs, protected by napkins, as far back upon the molars as possible, and then depressing the back part of the jaw, and at the same time raising the chin. The jaws should afterwards be secured by a bandage extending under the chin and over top of head.