Page 769 - My FlipBook

UPPER PROTRUSION. 767

Fig. 763 shows the use of piano M'ire after the method of Dr.
Jackson, which exphiins itself. The springs attached to the vulcanite
plate or to the Jackson base wire and crib " following around from each
side of the labial surfaces of the canines and incisors, pass each other at
the median line " and ])ress like long fingers.
For moving back the roots of the teeth after the crowns have been
moved, see page 796.
• Class D may include any of the others. The anchorage may be
insufficient for the first two classes on account of the loss of posterior
teeth from caries. In class C the teeth to be moved may exceed in

Fig. 766.

Writer's form of cap and bit for retraction.

number the anchor teeth so that the latter will move instead of the
anterior teeth. Figs. 764 and 765 show such a case. In such in-

FiG. 767.

The bit.
stances it is necessary to use the back of the head for anchorage.
The first recorded instance of such use was by Dr. Norman W.
Kingsley in 1865.
Various complicated appliances for attachment to the anterior teeth
have been described by different authors. Fig. 766 shows a very simple