Page 30 - My FlipBook

14 THE TIGHTENING OF LOOSE TEETH
to be ground off, or the upper margin of the retaining
apphance should extend to the cutting edges only.
Too much grinding may either weaken the upper part
of the tooth or cause breaking of an edge.
The grinding of the cutting edges of teeth of un-
equal size should be done only after drilling.
Next a die is cast on the plaster model by covering
the bottom of the oral cavity with moldine up to the
pencil line. On the side teeth two vertical walls should
be produced, and the front teeth invested up to their

Fig. 8.

edges. The model must be placed perpendicularly upon
the investing material, so as to insure immobility of the
metal to be swaged. Finally, a wall is erected in a
direction parallel to the bottom of the oral cavity.
Thus is built up a quadrangular box of moldine, in
which only the teeth are visible.
Large interdental spaces also should be filled with
moldine, in order to prevent overhanging places in the
matrix from being formed (Fig. 8).