Page 30 - My FlipBook

26 INTRODUCTION.

food will prevent it, and on the inner surfaces, the
friction of the tongue; besides, wherever there is a
free flow of saliva, this will have a counteracting
effect. Decay goes on very rapidly, after it has once
commenced, upon teeth affected by this deposit.
There are points of dissimilarity between this green

tartar or stain and salivary calculus, that it may be
well to notice. The latter is from the saliva; the
former from the mucus; and hence the one exists
Avhere there is an abundant flow of saliva, and the
other where the relative quantity of this is small. The
calculus is deposited when the saliva is in an alkaline
condition; the stain, when the mucus is very acid.
The former is deposited in large quantities and thick
incrustations, and upon the surfaces of the teeth, and
is easily removed without detriment to their substance;

whereas the latter is a thin film, barely sufficient to
stain the surface, and yet it enters into the tooth-
substance itself, and cannot be removed without
detaching some portion of the tooth with it. The one
seems rather preventive of caries, which does not occur
beneath it; but the other is highly promotive of decay.
With these marked features of difference, it is sur-
prising that the two should ever have been confounded,
since it is so important that the distinctive character
of each be understood, in order to its correct treatment.
Treatment.—In order to a perfect and final remedy