Page 142 - My FlipBook

caries as well as possible. If we can prevent caries or cure
it in its earlier stages we prevent this whole train of dis-
eases that follow.
Caries, in its simplest expression—leaving out causation
from consideration for the present—consists simply in a chem-
ical dissolution of the lime salts of the tooth, followed by
the decomposition of the matrix or gelatinous body which is
left after the solution of the lime salts. In caries of the
enamel the whole substance of the tissue is removed by the
solution of the lime salts, there being practically no basic
substance in the enamel; or, if any, so little that it will not
hang together; consequently, a cavity is formed by the sim-
ple solution of the lime salts of which the enamel is com-
posed. This begins always upon the surface, never in the
interior. Decay of the teeth is produced by an agent act-
ing from without, never from within. It is something ex-
traneous to the tooth acting upon the surface in the begin-
ning and penetrating little by little into the substance of the
tooth. Caries of the dentin is slightly different from caries
of the enamel, in that there is an animal substance in the
dentin that is sufficient in amount and consistence to retain
its histological and physical forms after the solution of the
lime salts. When the lime salts have been all dissolved out
from the dentin the form of the tissue and the form of the
tooth will remain complete ; consequently, the simple solution
of the lime salts of the dentin does not form a cavity. After
the solution of the lime salts there is a decomposition of
the basic substance or animal substance of the tooth progress-
ing from without inward, breaking up and decomposing this
basic substance and forming a cavity. Now, between the
solution of the lime salts and the decomposition
of the basic substance some little time transpires. Indeed,
the lime salts are not dissolved complete in a body in the
first instance from without inward, but the acid
seems to spread within the tissue and the solution
goes on as a softening process ; first, a portion of
the lime salts is dissolved, the acid penetrating farther and
a further portion dissolved, so that it is a progressive soften-
ing from without inward. In the outer portion of the soften-
ing area perhaps all of the lime salts are removed and in
the inner portion but very little of the lime salts are yet
removed. In this way it progresses slowly from without in-
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