Page 97 - REMOVABLE ORTHODONTIC APPLIANCES

Chairside management 89

adjustment, grasp the wire closer to the hinge that the impression material is well extended
to avoid damage. and fully attached to the tray.
The appliance should be fitted within 1 or
2 weeks after the impression has been taken.
Maun cutting pliers • At the time of fitting pick up the appliance
and run the fingers over the baseplate -
These are a robust pair of wire cutting pliers, particularly the fitting surface - checking for
which will be suitable for cutting stainless steel any sharp areas. Air bubbles on the model
wires of the dimensions commonly used for can produce roughness of the acrylic but
removable appliances (Figure 10.4). If these are such areas can be quickly smoothed, as can
not available a pair of wire cutters that can cut any sharp ends of wire.
wire up to 1.25 mm in diameter will be needed. • Show the appliance to the patient and
demonstrate the retaining clasps and active
springs, drawing attention to the need to
Measuring instruments take care not to distort any of the active
parts of the appliance during its insertion
A pair of stainless steel spring dividers enables and removal.
the distances between teeth to be measured
(Figure 10.5) and a 15 cm rule in millimetre
divisions is useful for measuring overjet and Retention
treatment changes.
This should always be checked carefully. If the
appliance is well made little adjustment will be
necessary. It should snap easily into place with
Fitting a new removable appliance finger pressure and be a firm fit, although read-
ily removable. Retention may be poor because
A removable appliance does not always need to the appliance is badly designed to resist the
be fitted immediately after teeth have been
extracted. In many cases it is possible to allow displacing forces to which it is subjected. Atten-
should
avoid this.
tion to design
spontaneous tooth movement to occur for a
month or more before the appliance is needed.
In other cases, where the space available for Adjustment of clasps
tooth movement is barely sufficient, the appli-
ance should be fitted before the extractions are Clasps made according to Adams' design offer
carried out. If there is any doubt about the good retention. Frequently, however, the oper-
patient's cooperation it is good practice to fit ator is presented with an appliance on which
the appliance and let it be worn for a time prior the clasps are faulty and adjustments may be
to the extractions. necessary.
When adjusting clasps the operator should
• The appliance should have been designed at avoid, as far as possible, bending the wire at
the time of taking the impression and with points where it has already been bent during
the patient still in the chair. It can represent construction by the technician. The only excep-
false economy to attempt to move too many tion to this rule is that where the clasps are
teeth with one appliance. Treatment will be initially too tight to permit insertion, it may be
better controlled and more rapidly necessary to grip each arrowhead in turn with
completed if a separate appliance is used for the pliers and bend it outwards (Figure 10.6).
each group of tooth movements. If up-to- Once the appliance can be seated (if necessary
date study models already exist then only a with the support of a finger) the accurate posi-
single impression for a working model is tioning of the arrowheads can be investigated.
required - otherwise an upper and lower Possible faults are as follows:
impression may be taken to provide study
model and a duplicate of the relevant model
for appliance construction. The impressions Horizontal
must be checked to ensure that there are no The arrowheads do not contact the tooth or
drags or large air bubbles and also to be sure else grip it too tightly.