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.
Xanthoxylum is a shrub growing in the northern middle and western States of North America. The bark is the officinal portion, and is obtained in the form of pieces, more or less quilled, of one or two lines in thickness and of a whitish color, with an ash-colored epidermis. It is quite inodorous and has a taste at first sweetish and slightly aromatic and afterwards bitter and acrid.
Xanthoxylum has been administered with considerable benefit in the chronic form of rheumatism.
Of powdered xanthoxylum, gr. x to 3ss, three or four times a day.
Xanthoxylum, in the form of the powder, has been applied with success to an aching pulp for the relief of odontalgia, and a decoction of the bark is employed as a wash for foul ulcers ; in the form of a tincture it is efficacious in relieving the soreness which remains after the extirpation of the dental pulp ; it is applied on floss silk or cotton. In the Southern States the Angelica Tree - Aralia Spinosa, sometimes called "Toothache Tree," is often called prickly-ash, but it differs from xanthoxylum, although its tincture answers for the relief of odontalgia.