Page 712 - My FlipBook

710 ORTHODONTIA AS AN OPERATIVE PROCEDURE.

'V\\v parent or Liiiardiaii should sec tliat the child follows the opera-
tor's directions carcfnlly, and should be given instructions as to the
course to pursue in case any appliances become dislodged. Wiicn screws
are used an intelligent parent or guardian may assist by turning them
according to instructions. If the ])aticnt is old enough, and desirous of
aiding, he may be intrusted with such duties. Screws or nuts should be
given about half a turn twice a da}-.
Rul)ber bands shoidd be renewed at least twice a week. I'iano-wire
springs should have their force renewed by bending (or straightening),
about twice a week.
Silk or linen ligatures should be renewed daily or at least every
other dav. They should be well waxed, as then they are applied more
readily. Moisture soon penetrates the wax and swells the fibers, pro-
ducing pressure in the direction intended.
Wire ligatures should be twisted daily (Figs. 726 and 727).
The amount of force which may be used will vary with individuals.
When a new appliance is used, no force should be applied for a few
days, till the patient becomes accustomed to the apparatus, then slight
force may be applied, and increased after a few days, but in no case
should excessive force be used. That is, in no case should force be used
strong enough to cause continued pain or loss of sleep, nor should it
make the teeth " tender " enough to prevent mastication.
Impressions should be taken of the teeth of both jaws in all but very

Angle's impression tray.
simple cases. Trays with high sides and flat floor should be used.
Those designed by Prof. Angle are especially adapted to the purpose
(Figs. 635 and 636).
Modeling compound is best adapted for impressions of most
cases. It should be placed in cold water and slowly heated in order to