Page 182 - My FlipBook

of the enamel, and, passing a sharp explorer over it — you
know that explorer will glide, smoothly over the perfect

enamel, but when coming in contact with this portion that
is sHghtly afifected by the solution of the Hme salts from be-
tween the enamel rods, it will catch, and if the solution has
gone a little farther it will enter the tissue a Httle. This is
the first sign of the beginning of decay. This you should
study carefully from mouth to mouth, and particularly study
the whitening Hnes, or whitening areas that stretch away to
this side or to that side of the carious area. Here is a little,
cavity, for instance, in the buccal surface of a tooth, an area
of decay ; it has broken through the enamel, has entered the
dentin, and you come to examine this and you will find
stretching away from it close to the free margin of the gum a
whitened area you place your explorer on the enamel of the
;
tooth a little farther to the occlusal and pass it along toward
the gingival, and as it comes to that whitened area it is in-
clined to catch. You should study carefully the location of
these. You will find that they stretch along near the free
border of the gum from the central area of decay toward the
angles of the tooth. Note carefully how far they reach to-
ward the angles of the tooth, toward the mesial, toward the
distal ; note carefully their breadth ; also note, carefully how
close to the gum line they extend, or if they extend fully to
the gum line. Now, the length and the breadth of these whit-
ened areas will mark the gravity of the case; they will mark
the lines to which extension must be made of your cavity
margins in order to prevent recurrence of decay in the fu-
ture. Just as sure as you leave any portion of that whitened
area outside of the margins of your cavity, just so sure will
decay recur about the margins of your filHng after it is made,
providing, always, that conditions remain the same. For
these whitened lines are marks of the beginnings of decay.
Now what I have said to you about caries will do you
very little good in your future practice if you do not study
these things carefully from mouth to mouth for yourselves.
Indeed, this study from mouth to mouth that you make
yourselves is that which gives you personal knowledge of the
conditions on which to act. One might study the micro-
scopic characters of caries until he knew every^ feature of it
perfectly well, had actual knowledge of it ; he might study
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