Page 244 - My FlipBook

124 PATHOLOGY OF THE HARD TISSUES OF THE TEETH.
differences whatever are found. Caries seems to pass through
the one just as readily as through the other. Therefore, from
this phase of the question, these differences are of no conse-
quence whatever.
Faults en the Structure of the Enamel.
Faults in the structure of the enamel, such as pits and
fissures, have already been spoken of as of importance in the
localization of beginnings of decay. The importance of these
has probably been overrated in the past. Very few of the pits
are properly termed faults. They are normal to the teeth. They
become faults only when they are abnormal in depth. Grooves
along the lines of junction of the lobes of the teeth are normal.
"When these are of such depth as to merit the term "fissure"
they are abnormal and are faults. These, even when faults,
are in no proper sense a cause of dental caries, but they furnish
favorable conditions for the action of that cause. They must
be regarded as giving opportunities for the beginning of decay
when conditions otherwise are favorable. But decay does not
begin in the pits of the teeth of immune persons, though these
pits may be just as deep and just as sharp as the pits in other
teeth which do decay rapidly, and even among those who
are very susceptible to decay, many pits will be seen without
decay, in those teeth that are decayed upon their proximal sur-
faces. This is so frequent that they are coming up continually
in the laboratory study of caries. In the illustrations accom-
panying this article, these will be seen in Figures 107, 108, 110.
Here we see that the pits have escaped the beginning of caries
when the patient has been sufficiently susceptible for proximal
decays to start and run a rapid course. So many of these occur
that we must regard the condition of immunity as entirely suf-
ficient to prevent decays starting in pits, unless the conditions
locally are particularly inviting. This may be said to be true
of all teeth which would be regarded as of normal conformation.
We occasionally find malformed teeth in which the pits and
fissures have failed of closure and in which some area of dentin
is actually exposed. This, however, is rare. Ordinarily, all of
the deeper pits have a fairly good layer of enamel covering the
dentin, but this forms no considerable barrier to the beginning
of decay, for. in susceptible persons, the enamel seems to decay
readily in such positions, while in those who are not susceptible
there is no decay in pits or elsewhere. I once obtained fourteen
teeth, mostly bicuspids and molars, from the mouth of a woman