Page 52 - REMOVABLE ORTHODONTIC APPLIANCES

44 Removable Orthodontic Appliances
head back. If the appliance is displaced, then
retention is inadequate.
When an Interlandi full headcap is used the
direction of force can be varied and it is possi-
ble to attach the elastics so that the force may
be directed slightly upwards as well as distally,
Figure 6.9 J hooks attached to hooks soldered to which helps retention. The high pull headgear
an anterior clasp. Note that these hooks are finished can only provide an upward and backward
in a complete circle to avoid sharp ends.
direction of pull.
It is important that the headgear should fit
snugly and be comfortable. It must be kept
clear of the ears. Long hair, which may make it
Headgear
awkward to fit a headcap, should be kept
The options are a full headcap such as an 'Inter- outside the straps. The straps themselves
landi', which uses elastics to provide the force, should be broad so that the load is well distrib-
or a high pull headgear, which may incorporate uted; otherwise enthusiastic use may rub the
springs to generate the force. Both systems can hair away, temporarily leaving a bald spot.
be effective in anchorage provision. The high Some headcaps incorporate studs, which are
pull headgear is simpler and quicker to fit but is nickel-plated and may cause an allergic reac-
more expensive. When fitting headgear it is tion at the point of contact with the skin.
important to avoid a downward component of
force, which tends to unseat a removable appli- Facebows
ance. Retention may seem adequate initially
but the appliance is likely to loosen with wear Facebows may be incorporated into the base-
so that the appliance then displaces. This plate if the appliance is worn only with head-
discourages patient cooperation and may even gear, as in the en-masse appliance (Figure 6.10).
make the appliance unwearable. A good test of This appliance has the advantage of being the
retention with headgear in place is to ask the safest way of applying extraoral force. More
patient to open the mouth widely and tip the commonly, the facebow has to be detachable

Figure 6.10 An upper removable appliance (en-masse appliance) to retract upper buccal segments with
extraoral force. Adams' clasp 64|46 (0.7 mm). Mid-line screw, integral extraoral bow (1.25 mm), inner bow
(1.0 mm).