Page 90 - My FlipBook

74 THE TREATMENT OF TEETH
structure, it would have taken far longer to insert
the gold, but the filling would have proved more
useful.
The question of shaping cavities for retention,
may be divided into a consideration of the older
or more general method, and the newer proceed-
ing perfected and introduced by Dr. Black. In
the older method the cervical walls are curved or
rounded, and retainage as well as maintenance
of integrity, or absence of rocking of the gold
during its condensation, is effected by means of
pits, grooves, and undercuts. Dr. Black's method
consists in broad, flat cervical walls ; cavity walls
at right angles to the floor ; the formation of sharp
angles at the lines of junction of the walls and the
floor, and the absence of all pits, grooves, or under-
cuts. There is no doubt that Dr. Black's method is
based on sound mechanical or engineering principles,
and that it facilitates the introduction and packing
of the gold in many cases, enabling the tilling to be
made more rapidly. An operator cannot, however,
always do exactly what he would like to do. There
is not always as much tooth structure left to work
upon as is desirable, and patients are not all blocks
of wood who will permit their teeth to be excavated
on exact mathematical lines. It is often necessary
to compromise, and whenever this can be done