f
the mouth favors germ propagation, that the twenty to thirty square
inches of surface constantly open to bacterial infection offer an
extensive breeding ground, and that the formation of the teeth invites
the lodgment of germs and of particles of food injurious both to teeth
and to other organs.

By scraping the teeth with the finger nail and noticing the odor you
can convince yourself of the presence of decomposing organic matter not
healthful to be carried into the stomach. By applying a little iodine
and then washing it off with water, your teeth may show stains. These
stains are called gelatinous plaques, which are transparent and
invisible to the naked eye except when colored by iodine. These plaques
protect the germs, which ferment and create the acid which destroys
tooth structure. Their formation can be prevented by vigorous brushing
and by eating hard food.

The individual with decayed teeth, even with unclean teeth, is open to
infection of the lungs, tonsils, stomach, glands, ears, nose, and
adenoid tissues. Every time food is taken, and at every act of
swallowing, germs flow over the tonsils into the stomach. Mouth
breathers with teeth in this condition cannot get one breath of
uncontaminated air, for every breath becomes infected with poisonous
emanations from the teeth. Bad teeth are frequently the sole cause of
bad breath and dyspepsia, and can convey to the system tuberculosis of
the lungs, glands, stomach, or nose, and many other transmissible
diseases. They may also cause enlarged tonsils and ear trouble.

Apart from decomposing food and stagnant septic matter from saliva
injured by indigestion, and by sputum which collects in the healthy
mouth, there are in many infected mouths pus, exudations from the
irritated and inflamed gum margins, gaseous emanations from decaying
teeth, putrescent pulp tissue, tartar, and chemical poisons. Every
spray from such a mouth in coughing, sneezing, or even talking or
reading, is laden with microbes which vitiate the air to be breathed by
others. Indigestion from imperfect mastication and imperfect salivation
(themselves often due solely to bad teeth) is far less serious than
indigestion from germ infection. Germs taken into the stomach can so
change the composition of saliva (a natural disinfectant when healthy)
as to render it no longer able to kill germs. Indigestion may result in
excess of uric acid and toxic material, so that the individual becomes
subject to