Page 18 - My FlipBook

METHODS OF FILLING TEETH.
4
be taken out of the cavity. Repeat this as often as a layer can be
started at its circumference. As soon as the last distinct layer has
been removed, scrape all the walls vigorously, removing even the soft-
ened dentine which may be clinging to them. The cavity will now be
clean, but the bottom of it will be soft. Still using the spoon, scrape
the bottom very gently, starting at the circumference and approach-
ing the center, removing all small particles which may be thus disen-
gaged, without actually cutting. A reliable germicide should now be
used on cotton, the cavity sealed with a phosphate cement, and so left
for two or three days, when the filling may be inserted with safety.
Non-carious dentine may be found beneath other than leathery
decay. If the carious portion is brown, or black, the demarcation is dis-
coverable by the color, softened dentine being usually of nearly normal
color. When it is found underlying decalcified enamel, the enamel
will come away as a white, chalky powder, and the dentine beneath
need be removed as for the retention of the This
only required filling.
condition is rarely observed except under "green-stain," and the de-
struction is a decalcification, rather than true caries. A corundum
stone should be used to remove the stain, when the decalcified enamel
will be its white color. The dentine beneath
readily distinguished by
is non-carious, but as the destruction is superficial there is little risk of
exposing the pulp, for which reason no special caution is needed be-
yond the usual care when operating on healthy dentine, not to cut
deeper than is actually necessary to correctly shape the cavity. It
may be said in passing that this decalcification of enamel due to or ac-
companying "green-stain" is usually associated with highly sensitive
dentine. This is fair presumptive evidence that the dentine is under-
going a change which by loss of lime-salts leaves a disproportionately
large amount of soft tissue. In this particular class of cases the sensi-
tiveness be controlled hot-air blasts to
may usually sufficiently by
allow rapid preparation of the cavity with sharp engine-burs.
Retentive The cleansed of the next
shaping. cavity decay, impor-
tant object is to so shape it that the filling cannot be dislodged mechan-
after it has been inserted. To this sometimes taxes
ically accomplish
the utmost ingenuity of the most experienced, so that binding rules
cannot be formulated to cover all conditions. It will therefore be
best, in order to describe methods covering a wide field, to take up
individually the more common cavities, but before proceeding to that
discussion I shall present here a few general principles.
The great desideratum is to so form the cavity that the visible ex-
ternal surface of the when shall have a smaller diameter
filling, placed,
than some portion which is within the cavity. We should thus have
a mass a whose orifice would not
occupying cavity permit the passage
of its greatest diameter. Such a filling could not be removed mechan-