Page 201 - My FlipBook

or the cementum, and these odontoblasts lying in physio-
logical relation to nerves, the sensation produced by injury
of the fibrils which are a part of those cells is conveyed to
the sensorium and we feel pain. This sensitiveness is in-
creased, becomes hypersensitiveness, or hyperesthesia, dur-
ing the progress of caries, and especially so when the pro-
gress of caries is rapid. This is the general rule to which
there are some exceptions. The greatest degree of sen-
sitiveness is usually in the region of the dento-enamel junc-
tion, just as the greatest degree of sensitiveness in other
parts is just beneath or in the skin. When passing farther
into the tooth this sensitiveness is less acute. You will re-
member I told you that it was usually confined to the area
of the carious cavity, the other portions of the tooth not
becoming so acutely sensitive. Shallow cavities are usually
more sensitive than deep cavities, so far as sensitiveness
of the dentin is concerned. Now, we must divide sharply,
in our minds and in our observations in practice, sensitive-
ness in the dentin from that sensitiveness that comes from
touching a pulp; they are two distinct things. Pulps are
generally sensitive, sometimes very sensitive, sometimes very
slightly sensitive, owing to conditions.
While the general rule is that sensitiveness of the den-
tin is confined to the area of decay and inclined to be great-
est in broad, shallow cavities, we occasionally find cases
in which the dentin of the whole tooth is hypersensitive ; cut
into it anywhere and you will find the dentin of that particular
tooth extremely sensitive. There has been an excitation of
the nerves of that particular tooth that has developed a
peculiar hyperesthesia of the whole tooth. This sensitive-
ness does not include sensitiveness of the tooth to pressure
when this pressure comes upon the enamel ; we can gain
no information of it from that point ; we only find it upon
disturbing the dentinal fibrils. I remember a case in which
I found an extremely sensitive tooth in a little girl for whom

I was operating. She was a very good patient and I had
not had special trouble with sensitiveness in teeth that I
had filled previous to this one. It was a lower bicuspid that
had a mesial cavity, a distal cavity and a slight decay in a fis-
sure, so that I felt that it was necessary to make a mesio-disto-
occlusal cavity, and as decay was going pretty rapidly in her

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