Page 263 - My FlipBook

THE SALIVA. 135

the saliva, are matters of time, place and the prevalence of spe-
cial forms of these growths in the surroundings.
Under the idea that caries of the teeth was caused by acidity
of the saliva, this subject has, in the past, been regarded as very
important. I do not now so consider it. Acidity of the general
saliva does not become sufficient to cause caries. Those immune
to caries have saliva fully as acid as those most intensely sus-
ceptible to caries. The two seem not at all related as cause
and effect. Microorganisms produce caries only when they are
secluded from the general saliva by some kind of covering, as
has been sufficiently indicated on previous pages. Conditions of
the saliva that enable microorganisms to form these coverings,
or which form them independently of the action of microorgan-
isms, are, apparently, the important objects of search. It is in
no proper sense a search for conditions in which microorganisms
will or will not grow in the saliva. They grow in all conditions
yet found, and just as freely in the saliva of immune persons as
in the saliva of the most susceptible.

VISCOSITY OF THE SALIVA.
If the conditions of the fluids of the mouth be studied from
week to week, in each of a considerable number of persons with
reference to accumulations on the teeth, it will be found that
the saliva of some persons is habitually very thin and watery,
and that the teeth are habitually clean. The saliva of other per-
sons will be thicker and more viscous. This latter may be drawn
out into long threads by touching the finger to it and drawing it.
This has been termed "ropy saliva" or "viscous saliva." Gen-
erally the teeth will be difficult to keep clean when the saliva is
ropy. The person may, by care, keep the teeth looking well, but
a close examination will show them to be covered by a trans-
parent slimy material of sufficient thickness to be clearly appar-
ent. If this be cleaned away, a new deposit will be found the
next day. In many of these cases, if the saliva be touched by a
rapidly rotating disk or stone, it will quickly thicken up into a
more or less firm coagulum around the disk or stone, reminding
one of the clotting of fibrin. The opportunity to observe this
can be best obtained by holding the buccal mucous membrane
well away from the lower bicuspids and molars with one finger
and waiting a little for some accumulation of saliva and then
touching the margin of the rapidly rotating disk or stone to the
surface of this accumulation. Often the saliva will quickly ball