Page 30 - REMOVABLE ORTHODONTIC APPLIANCES

22 Removable Orthodontic Appliances
Buccal springs them unpopular with patients). They are rela-
tively unstable in the vertical dimension (see
These springs can be used for mesio-distal Figure 3.4) which can make them difficult to
tooth movements, palatal tooth movement and, adjust, because if the spring acts on a sloping
in conjunction with some form of bonded surface, it will tend to slide along the incline.
attachment to a tooth, occlusal movement, An unsupported buccal spring has to be
rotation or buccal movement. Care needs to be constructed from 0.7 mm wire to provide stabil-
taken during construction so that they do not ity and will be much less flexible than a palatal
intrude too deeply into the buccal sulcus. spring, so that a small deflection generates a
Instructing the patient on how to remove the large force.
appliance should specifically address the ease In view of these problems, particularly care-
with which the buccal springs may be distorted. ful attention has to be given to the design and
construction of a buccal spring. The impression
must adequately reproduce the buccal sulcus
Buccal canine retractor and show the muscle attachments so that the
spring can be kept clear of them. The spring
A buccal spring is used where a buccally placed should extend as far as the mucosal reflection
canine has to be moved palatally as well as and lie just clear of the attached mucosa. The
distally - an operation for which a palatal outline of the spring is drawn on the model. The
spring is not satisfactory. Buccal springs are coil lies just distal to the long axis of the tooth,
liable to be uncomfortable (which can make while the anterior limb of the spring passes
down from the coil to the middle of the crown
and is carried round, in contact with the tooth,
to the mesial contact area. This design is more
stable, making control of distal and palatal
tooth movements simpler than with the
conventional buccal retractor (Houston and
Waters, 1977). The distal limb of the spring is
carried through to the baseplate, in contact
with the second premolar and above its contact
area.

Adjustment
The spring should be activated by only 1 mm,
otherwise the force will be excessive. Provided
that it has been constructed to contact the
tooth correctly, adjustment is simple. Distal
activation is effected at the coil by bending the
anterior limb over the round beak of a pair of
spring-forming pliers (Figure 3.16). Palatal
activation is undertaken in the anterior limb
after it emerges from the coil. When the appli-
ance is inserted, the spring may catch on the
cuspal incline of the canine and the patient
should be instructed to check and correct this
if necessary.

S u p p o r t e d buccal retractor
This spring (see Figure 3.6) is identical in
design to the buccal retractor described above
Figure 3.16 Adjustment of a buccal canine
retractor. but is made from 0.5 mm wire supported in