Page 180 - My FlipBook

cases, and gives the saliva a ropey consistency, for usually the
saliva as poured from the salivary glands proper is a very thin,
motile, watery liquid, mostly composed of water, while the
mucus coming from these other glands scattered about the
mucous membrane is thick and viscid, and the comparative
amounts of these two fluids have very considerable influence
over the character of the mixed saliva of the mouth.
Now% from time immemorial, almost, the profession
and the laity as well have seemed to regard caries as being-
caused by acids. If we go back 200 years, or 300 years, and
get hold of the advertisements of tooth pastes, tooth washes,
etc., we will find this prominently set forth to catch the eyes
of the public. They generally claimed that these nostrums
destroyed the acidity of the mouth and thus prevented caries.
It is true, however, that in these olden times the medical pro-
fession regarded caries as caused by inflammatory processes.
This idea was not broken down until after the beginning of
this century, or until after microscopic studies of the teeth had
been made which showed plainlv that caries of the teeth could
not be caused by inflammatory processes, because the teeth
were not vascular—had no circulation of blood—and could
not become inflamed. These studies broke down the notion
of inflammatory processes in caries of the teeth. I say en-
tirely so—there have been a few popping up here and there
since who have claimed inflammatory processes in the teeth»
and even in the enamel, but thev have been in a very great
minority, and their claims have never had very much in-
fluence since about 1830. Now this idea that caries is
caused by acidity of the fluids of the mouth has been pre-
valent for so long a time that it seems difficult for the ordi-
nary man to get it out of his mind. I think I have told you
time and again, perhaps, that caries of the teeth is not caused
by acidity of the saliva. Continuous acidity of the saliva is-
no evidence whatever that caries will occur, for in the ex-
aminations that have been followed from year to year of
persons immune to caries we have found generally that their
mixed saliva is acid in reaction, and as intensely acid as in
those in whom caries was rapidly progressing. If any of you
have had it fixed in your mind that acidity of the fluids of
the mouth was in any degree a causitive influence in pro-
ducing caries, you should abandon it at once for the evi-

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