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.
Medicinal substances are applied to the mucous membrane of the mouth and to the dental structures almost exclusively for local effects. In dental practice antiseptic remedies are extensively employed to arrest fermentative and putrefactive processes, as every kind of fermentation depends upon the growth and increase of a living organism. Various diseases of the dental structures have a close relationship with low organisms in the morbid processes which result during their progress, and which are maintained and developed by the presence of living matter. The remedies recognized as belonging to the group of antiseptics, when brought into contact with the disease germs, which are constituted of these organized forms of life, have the power of destroying their vitality and of arresting the fermentative or putrefactive process which they either develop or promote. The effect of escharotics when applied to a part of which the structure and vitality are to be destroyed, is to produce an eschar and incite inflammation and suppuration of the adjacent tissues, by which the slough is separated from the living parts.
Medicinal substances are applied to the mucous membrane of the mouth in the form of gargles or mouth-washes, lotions and injections, and generally for a local effect.
Medicinal substances are applied to the skin for both a local and general effect, either by friction, by the endermic, or by the hypodermic methods. In the endermic method, the cuticle is usually removed by the action of a blister, and the medicinal agent is applied to the denuded surface in the form of a powder or ointment, and is a useful method when the irritability of the stomach or difficult deglutition prevents medicines from being taken through the mouth.