Page 178 - My FlipBook

162 HUNTER ON THE TEETH.
duces similar effects to those of powdered crystal. When this
has crumbled away, the bony part of the Tooth is exposed ; and
when the disease has attacked this part, it generally appears
like a dark brown spec. Sometimes however, there is no change
of colour, and therefore the disease is not observable, till it has
made a considerable hole in the Tooth. The dead part is
generally at first round, but not always ; its particular figure
depending more on the place where it begins, than on any other
circumstance It is often observed in the hollow parts of the
grinding surface of the Molarcs, and there looks like a crack
filled with a very black substance. In the incisors, the disease
usually begins pretty near the neck of the Tooth, and the
scooping process goes on enlarging the cavity, commonly across
the same part of the Tooth, which almost divides it into two.
When such a diseased Tooth gives way, the mischief is occa-
sioned by its body breaking off.
When it attacks the bony part it appears first to destroy the
earth, for the bone becomes softer and softer, and is at last so
soft on the exterior exposed surface, that it canbe picked away
with a pin, and when allowed to dry, it cracks like dried clay.
It begins sometimes in the inside of the Tooth, although but
rarely. In this case the Tooth becomes of a shining black, from
the dark colour being seen through the remaining shell of the
Tooth, and no hole is found leading into the cavity, (b)
This blackness is seldom more than a portion of the bony part

(b) [Mr. Bell, who regards inflammation as the true proximate cause
of dental caries, asserts that the situation in which the disease com-
mences is invariably under the enamel upon the surface of the dentine.
All recent authorities are, however, agreed that caries commences on
the surface of the enamel, and gradually makes its way to the pulp
cavity. Those who have maintained the contrary opinion have been
misled by the spreading of the disease under the enamel, while the
surface of the enamel in some rare instances appears to be almost intact.
A careful examination of such teeth will, however, show the presence
of cracks or fissures in the enamel through which the fluids of the mouth
have found their way to the surface of the dentine. |