Page 212 - My FlipBook

requires more force of the mallet to condense gold to a given
density in the teeth of children than in the teeth of adults.
The force of a blow is measured, not so much by the momen-
tum given the mallet as by the resistance offered to the mal-
let. It is the old story told of the Irishman who said, after
he had received an injury from a fall: ''Shure, sur, it was
not the fall that hurt me, it was shtoppin' so quick."
(Laughter.) And it is just so with the blow of the mallet;
the number of pounds condensing power in the blow does not
depend so much upon the momentum with which the mallet
strikes as the resistance ofifered. And the peridental mem-
branes of the teeth of children are very much thicker than
the peridental jnembranes of the teeth of adults, so that they
give more, ann it really requires from one-third to one-half
more blow to produce the same result. It is demonstrable
by actual tests with falling weights, that a little more spring
in the resistance makes that difference, and it is a dif¥eience
that you should study carefully and guard against in con-
densing fillings in the mouths of children. This less resist-
ance, because of the greater spring in the peridental mem-
branes of the teeth of children, is important. This is one of
the difficulties met with in doing operations for children, in
addition to the fact that they do not bear pain so well. In
persons older the conditions are better, the teeth are firmer
in their sockets, a blow counts for more, and the percentage
of success in making permanent fillings should be much
greater. Take patients from sixteen to twenty-two, tor in-
stance, and if you keep your records as you should you will
find a large mass of the work you do will be for people be-
tween sixteen and twenty-two, or that those you do later
will be more in the line of refilling than filling denovo cavities.
In these fillings the condition| should generally be such that
you can make permanent work. But to do this requires that
you develop a great amount of skill.
There will be some patients who are older coming to you
who have small cavities that have begun, perhaps, in their
teens, decayed very slowly, stopped for a time, then condi-
tions of susceptibility coming up again, decaying a little
more, stopping for a time and then decaying a little more.
You will have these cavities coming to you, that patients
have not noticed until one has broken through to the oc-
200