Page 183 - My FlipBook

niicro-organisms, grow them in all their stages and condi-
tion^ and know micro-organisms perfectly well, and yet, if
he does not malce these studies of caries from mouth to
mouth and become acquainted so that he has personal knowl-
edge of these conditions of his own, these microscopic
studies, these studies of bacteriology will be of little or no
avail. They are valuable as a preparation for these studies
from mouth to mouth ; they are necessary as pointing out the
way to make these studies from mouth to mouth. That
which is of real intrinsic importance to you is to gain the
ability to study these things from mouth to mouth and make
them the factors of knowledge upon which you will act in the
practice of dentistry.
Tlic dentist must carefully avoid making the conditions for
the beginning of caries of the teeth, for it is easy in dental
practice to often make the conditions for the beginning of
decay about fillings. Remember that in driving on a band,
if there is a portion not properly protected by cement, caries
will begin under it, because the band acts to prevent the dis-
sipation of the acids formed by micro-organisms that will
grow under it, and creates the condition to produce caries.
The same may be done by leaving overlaps about fillings un-
der which micro-organisms may grow. A filling may be very
perfectly finished, may be a beautiful filling, may be well
done in every other way, but somewhere about the gingival
margin or the angle of the tooth w^here it is difficult to see
well, you haven't cut the filling down properly and an overlap
is left. That overlap, if there is any predisposition to decay
in the mouth, will cause a recurrence of decay at that point,
for the reason that it is not fit accurately against the tooth,
leaving a space under which micro-organisms may grow, and
protect the acids they form from dissipation in the saliva
and allow them to act upoii the tooth. Then, again, by not
.cutting away sufficiently, so that you leave a margin in con-
tact with another tooth, so that the fluids of the mouth do not
wash it well, gives a point of lodgment for micro-organisms,
a point where the acids, if thev form, will be applied directly
to the tooth, and there you will have a breaking down, a re-
currence of decay and a failure. It is the study of these
points from mouth to mouth. Know the cause, and then
study these until they become second nature to you—be
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