Page 98 - REMOVABLE ORTHODONTIC APPLIANCES

90 Removable Orthodontic Appliances

Figure10.6 Occasionally it is necessary to bend the
arrowhead of an Adams' clasp.

Vertical
The arrowheads grip too far occlusally or else
push up into the gingivae.
These faults can be corrected in most cases by
a combination of bends at two points (Figure
10.7). Bending the wire just beyond the point Figure 10.8 (a) The arrowhead is pushing into the
where it has passed over the embrasure controls gingival margin, (b) First adjustment at point X
its vertical position. Bending it nearer to the moves the arrowhead away from the tooth, (c)
Second adjustment restores tooth contact with the
arrowhead controls its bucco-lingual position.
arrowhead at the correct height.

If the arrowhead grips too far occlusally it
can be moved buccally by an adjustment at
point Y. A further adjustment at point X will
then bring it into contact at the correct position
(Figure 10.9).
It is important that the clasp does not grip the
Figure 10.7 The fit of a clasp can be adjusted by tooth too tightly and an undercut of 0.25 mm
bending the wire at two points. Adjustment at X has been shown to give an adequate clasp. It is
moves the arrowhead vertically; adjustment at Y useless to attempt to tighten the clasp by bend-
moves it horizontally.
ing the wire at the point where it emerges from
the acrylic. This will merely interfere with the
Take as an example a clasp that is found to passage of the wire across the embrasure and
have an arrowhead pushing into the gingivae prevent full seating of the appliance. The only
(Figure 10.8a). The wire can be bent at point X indication for adjustment at this point occurs in
to move the arrowhead occlusally (Figure a case where the wire passes high over the
10.8b). The height will be corrected but the embrasure and interferes with the occlusion.
adjustment will also have the effect of moving Poor retention may be due to a conically
the arrowhead away from the tooth. A bend shaped tooth, which offers little undercut. This
can then be placed at point Y to compensate for is especially common when second molars are
this (Figure 10.8c). being clasped.