Page 155 - My FlipBook

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Too hard or improper tooth-brushes in some cases, seem
to injure the teeth, especially young teeth. And in fine,
all chemical and mechanical causes which
act upon the
teeth, so as to destroy their substance, enamel, &c. prove
a cause indirectly of caries of the teeth, by rendering
them much more liable to be acted upon by vitiated
juices of the mouth.
The appearances of superficial
caries are very various,
both as regards its shape, colour and situation.
At times, the decay is confined to a small point, at others,
it spreads superficially, like an irregular patch.
Often we notice a large internal cavity, with a small hole
through the enamel ; the reason of this is, that the bone of
the tooth is much more liable to decay than the enamel, and
after the caries has penetrated the enamel, it proceeds much
more rapidly within the tooth than on the enamel.
Sometimes the front of the upper incisores and canine
teeth, appear as if scooped out, as it were, by the process of
decay, and also the sides of the jaw teeth, are often affected
in the same manner.
Very often caries commences at those parts where the
teeth are in contact with each other, because foreign matters
are most easily retained there ; and the enamel is much the
thinnest, and for the same reason, it appears often in small
cavities of the crowns of the grinding teeth, and near the
necks of the teeth where the enamel becomes attenuated.
The various colours of caries make no practical difference
in the practice for their cure, &c.
Internal caries, says Mr. Hunter, is detected by a peculiar
shining black appearance from the dark caries being seen
through the enamel, before it has proceeded so far as to break
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