Page 186 - My FlipBook

ICO TUE MICRO-O-RGAKISMS OF THE HUMAN MOUTH.

restores its transparency. Xow, dentine consists, on the one
hand, of the basis-substance infiltrated with lime-salts, and on
the other of the dentinal tubules, with their contents ; and since
both these constituents of dentine have different coefficients of
refraction, an opaque tissue is formed. We may diminish the
opacity—that is, increase the transparency—by filling the dentinal
tubules with a substance which has the same coefficient of re-
fraction as the basis-substance, or by transforming the basis-sub-
stance so as to make it resemble the contents of the tubules in
respect to refraction.
In spite of the many attempts to account for the increased
transparenc}- of the dentine under certain conditions, itsi true
cause has not yet been established with certainty. J. Tomes '"^
and Magitot^*'^ explain transparency by the calcification of the
dentinal fibrils. Both authors regard it as the result of a vital
process—an attempt made by nature to impede the progress of
the disease. Later, Tomes ^^ seems to have doubted the correct-
ness of his former views. C. Wedl ^^^ regards the transparency
occurring in dental decay as identical with that appearing in the
roots of senile teeth. He doubts the correctness of the calcifi-
cation theory, without giving further expression to his o\Vn.
Leber and Rottenstein ^^ ascribe transparency to a partial de-
calcification of the dentine.
Schlenker"^ seems to be of the same opinion.
It has also been attempted to explain the transparency of the
dentine by the obliteration of the dentinal tubules brought about
by the swelling of the basis-structure.
Since, however, the swelling or expansion of a porous body is
not accompanied l)y obliteration of the pores, but, on the other
hand, naturally implies a corresponding enlargement of them, an
obliteration by swelling is a physical impossiljility. According
to WalkhoftV^^ " transparency has also been explained as the con-
sequence of micrococci." I have found no such view expressed
anywhere, either by Milles and Underwood or any other advo-
cate of the chemico-parasitical theory of decay.
\YalkhofF concludes from his experiments " that transparency
must be regarded as a sclerotic action of the dentine-fibers, by
which they form new basis-substance at their own expense. Its