Page 168 - My FlipBook

156 MECHANICAL DENTISTRY AND METALLURGY.
been accomplished, the health of the surrounding- tissue, the
occlusion of the teeth, etc. In some cases, as where the
upper incisors have been moved from a lingual to a normal
occlusion, a few days' retention will suffice, as the occlusion
of the teeth will support them in their new position. There
are other conditions, as for instance, where the anterior
upper teeth had been retracted, a much longer time, from
six months to a year, being necessary. This is true par-
ticularly in cases of rotation, where, owing to the severe
disturbance of the fibers of the peridental membrane, a
mechanical retention of a year or more is usually advisable.
This would apply to patients eighteen to twenty years of
age or more; if the patient was but twelve years of age
possibly half that time, or six months, would be all that
was necessary.
The class of anchorage, or retaining device, depends upon
the nature of the irregularity corrected.
1. Where the tendency of the teeth is to move in dif-
ferent directions, we may use a reciprocal appliance. That
is, the bracing of one tooth against another.
2. The use of teeth already firm in the arch for an-
chorage.
3. Removable devices, such as rul^ber plates, with attach-
ments.
4. The correct occlusion of the teeth.
When a single tooth has been rotated, a small band and
a short projecting wire or spur will retain it in position.
It is probably better, however, to have two spurs, as shown
in Fig. 117. When two approximating teeth have been
rotated in opposite directions, a simple but very effective
retainer is to make a thin gold band to fit each tooth, tack
them together with a little solder, then cement in position.
A more complicated case of rotation, inolving the centrals
and lateral incisors, could Ije anchored by a very simple but