Page 778 - My FlipBook

77G ORTHODONTIA AS AN OPERATIVE PROCEDURE.

soldered to bands upon tlio distal angles of the canines, while a piece of
gold wire attached by solder connects these bands and ])asses in front
of the incisors." This cap and traction bar may be used in connection
with this appliance by applying the latter to the projection in front.

Fio. 783.

Allan s aiijihaiic'c.
While more complicated than the appliance shown in Fig. 760, it must
be very efficient.
Constant force may be used by such an ap]>liance as is shown in
Figs. 762 or 763. The form of plate should be modified for the lower
arch.
When the posterior teeth do not give sufficient anchorage, an exter-
nal appliance must be resorted to. The cap and bit shown in Fig. 766
may be applied to the lower teeth, or Angle's appliance (Fig. 770) may
be used if the six anterior teeth are not in proper alignment in respect
to each other.
If the protrusion is an example of true prognathism—that is, due
to the lower maxilla being larger or longer than the upper from either
of the causes mentioned—external force alone can be of use.
By a cup of metal swaged to fit the chin and connected by rubber
bands with a cap on the back of the head, as shown in Fig. 783 or in
Fig. 784, the protrusion may be reduced.
How this is accomplished is a matter of dispute, some maintaining
that the lower maxilla is bent at the angle and others that the condyle
is pushed back in the glenoid cavity. Dr. G. S. Allan said in 1878,