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6
MECHANICAL DENTISTRY AND METALLURGY.
1
injury to the root, by cutting two parallel grooves, opposite
each other, on the labial and palatal surfaces, with a small
circular saw, or a hard rubber or rubber and corundum disc.
These grooves should be cut through the enamel deep into
the dentine. Then with the excising forceps, the cutting
edges of which are placed in the groove, the crown is readily
severed from the root.
^ After the use of the discs and excising
riG. 123. . ^
. . .
forceps, any remaining portions project-
ing beyond the free margins of the gum
should be removed and proper shape given
to the end of the root. A flat-edged
corundum stone, or what are known as
the Ottolengui root facers (Fig. 123), are
the best for the purpose. If stones are
used they should be kept constantly wet
and free from clogging particles of tooth
substance. The end of the root should
be dressed down, anteriorly, a little below
the free margin of the gum, care being taken not to cause
unnecessary laceration; in this way the artificial crown,
when adjusted to the root, will unite so intimately with the
gum in front, in ordinary cases, as to render exposure un-
necessary. The surface of the root prepared in this manner
will present a concavity corresponding with the festoon of
the gum.
If a living pulp remains in the root, it will not ordinarily
be practicable,— unless there is partial obliteration and con-
sequent recession of the pulp cavity as the result of ossific
deposits,—either to cut off the tooth on a line with the gum
or even transversely, or to dress the root even with the gum,
without inflicting insufferable pain. It will be necessary,
therefore, under such circumstances, either to devitalize
and extirpate the pul[) through the carious opening in the
MECHANICAL DENTISTRY AND METALLURGY.
1
injury to the root, by cutting two parallel grooves, opposite
each other, on the labial and palatal surfaces, with a small
circular saw, or a hard rubber or rubber and corundum disc.
These grooves should be cut through the enamel deep into
the dentine. Then with the excising forceps, the cutting
edges of which are placed in the groove, the crown is readily
severed from the root.
^ After the use of the discs and excising
riG. 123. . ^
. . .
forceps, any remaining portions project-
ing beyond the free margins of the gum
should be removed and proper shape given
to the end of the root. A flat-edged
corundum stone, or what are known as
the Ottolengui root facers (Fig. 123), are
the best for the purpose. If stones are
used they should be kept constantly wet
and free from clogging particles of tooth
substance. The end of the root should
be dressed down, anteriorly, a little below
the free margin of the gum, care being taken not to cause
unnecessary laceration; in this way the artificial crown,
when adjusted to the root, will unite so intimately with the
gum in front, in ordinary cases, as to render exposure un-
necessary. The surface of the root prepared in this manner
will present a concavity corresponding with the festoon of
the gum.
If a living pulp remains in the root, it will not ordinarily
be practicable,— unless there is partial obliteration and con-
sequent recession of the pulp cavity as the result of ossific
deposits,—either to cut off the tooth on a line with the gum
or even transversely, or to dress the root even with the gum,
without inflicting insufferable pain. It will be necessary,
therefore, under such circumstances, either to devitalize
and extirpate the pul[) through the carious opening in the
