Page 260 - My FlipBook

132 PATHOLOGY OF THE HARD TISSUES OF THE TEETH.
these salts to the percentage of dental caries, the relation of the
amount of saliva secreted by the person to the percentage of
caries, the relation of salts in drinking water to the development
of the salivary glands, etc. The examinations have been mostly
made in children. These have been widely distributed in Ger-
many, Switzerland, Denmark, Sweden, etc. The work is still
in progress.
This mention of work being done is given here to show the
direction which thought is taking and the activity manifested,
rather than for the purpose of giving specific information of its
detail. The questions are of very recent origin. The question
of immunity and susceptibility to dental caries as a systemic con-
dition as known to-day, was first propounded in 1895. Years
will probably be required before this problem, involved in such
obscurity and difficulty, can be so unfolded and simplified that
the general profession may make practical use of it in the treat-
ment of dental caries. In the meantime, the general discussion
of it belongs to the journal literature rather than to books.
The Saliva.
When the saliva is mentioned without designation of its
special parts, it is most generally understood that the mixed
fluid found in the mouth is meant. This is made up of secretions
from several sources, any of which may be examined separately.
These are the saliva from the parotid gland, saliva from the
submaxillary and sublingual glands, and mucus from the mucous
follicles situated in the mucous membrane of the mouth. The
different salivas are much alike. Though variable, they are
generally very limpid, watery secretions. The mucus, on the
other hand, is more generally found to be a thick, ropy secretion.
If the parotid saliva is collected directly from Stenson's duct
it will generally be found to be about neutral in its reaction with
litmus, varying from slightly alkaline to slightly acid. If the
mucous membrane of the mouth, say the roof of the mouth, is
dried and the mouth held open for some time, one will generally
find here and there globules of fluid collecting on its surface.
Sometimes many of these will be seen ; sometimes very few, and,
occasionally, none without a very long wait. The secretion seems
to be very variable. Touching litmus to this generally brings a
very definite acid reaction. In the lips, I have usually found
much larger glands than elsewhere in the mucous membrane.
Some of the larger of these seem to emit a much more watery
fluid than the usual submucous glands. It is more of the nature