n, are habits
which are very prejudicial to the teeth and gums. In this way the
mouth forms a trap to catch the dust and gritty particles floating in
the atmosphere, which soon mechanically injure the enamel of the teeth
by attrition.

On the subject of cleanliness in connection with the teeth and mouth,
it may be said that the mouth cannot be too frequently rinsed during
the day, and that it should be more particularly so treated after each
meal. Pure cold water is the best for the purpose. It not only cleans
the teeth and mouth, but exerts a tonic action on the gums, which warm
water, or even tepid water, is deficient in. When cold water cannot be
tolerated, tepid water may be employed, the temperature being slightly
lowered once every week or ten days until cold water can be borne.
Every one who abhors a foetid breath, rotten teeth, and the
toothache, would do well to thoroughly clean his teeth at bedtime,
observing to well rinse the mouth with cold water on rising in the
morning, and again in the day once, or oftener, as the opportunities
occur. With smokers, the use of the toothbrush the last thing at night
is almost obligatory if they value their teeth and wish to avoid the
unpleasant flavor and sensation which teeth fouled with tobacco smoke
occasion in the mouth on awakening in the morning.

As to tooth powders or pastes to be used with the brush, the simplest
are the best. Plain camphorated chalk, with or without a little finely
powdered pumice stone or burnt hartshorn, is a popular and excellent
tooth powder. It is capable of exerting sufficient friction under the
brush to ensure pearly whiteness of the teeth without injuring the
enamel, whilst the camphor in it tends to destroy the animalcula in
the secretions of the mouth, whose skeletons or remains constitute, as
we shall presently see, the incrassation popularly called "tartar."
Recently-burnt charcoal, in very fine powder, is another excellent
tooth powder, which, without injuring the enamel, is sufficiently
gritty to clean the teeth and remove the tartar from them, and
possesses the advantage of also removing the offensive odor arising
from rotten teeth and from decomposing organic matter. The charcoal of
the heavy hardwoods, as lignum-vitae, boxwood, oak, are the best; and
these, as to quality, range in the order given. Still more valuable as
a dentifrice is areca nut charcoal, which, besides possessing the
properties of the other vegetable charcoals