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P. 92

84     Removable  Orthodontic  Appliances
            lowers.  As  with  a  single  instanding  incisor,  Retention
            correction  will  not  be  stable  unless  there  is  a  Clasps on 6|6 and 1|1 with  a  screw to move  the
            positive overbite  at the end  of treatment.   labial  segment  forwards.

                                                   Anchorage
            An  appliance to  procline the  upper  labial
                                                   The  teeth  that  are  clasped  provide  adequate
            segment  (Figure  9.8)
                                                   anchorage.
            Active  component
            Double  cantilever  springs  (or  cranked  finger  Baseplate
            springs,  as  described  for  single  instanding  Posterior  bite  planes  are  used  to  clear  the
            incisors) can be used.  In this case, DID or 4J4   occlusion in the  incisor region by about  1 mm.
            might  be  clasped  to  resist  the  displacing  Where a screw is used, the baseplate is split.
            effect  of the  spring.  When  anterior retention
            is a problem  a screw can be used (Figure 9.9).   Points  to  note
            This  has  the  advantage  of  being  simple  for  Patients  sometimes  find  a  screw  positioned  at
            the  patient to manage  and  allowing retention   the  front of the  mouth to be  rather bulky. The
            to  be  improved  by  clasping  the  central  patient is instructed to turn the screw one quar-
            incisors.                              ter-turn  per week.

















                                                          Figure  9.8  An  appliance  to  procline the
                                                          upper labial segment. Adams' clasps 64|46
                                                          (0.7  mm),  palatal  cantilever springs
                                                          (0.6  mm)  and  molar capping.

















                                                          Figure  9.9  An  appliance  to  procline  21|12.
                                                          Adams' clasps 6|6  (0.7  mm), double Adams'
                                                          clasps on 1|1. (0.7  mm),  molar capping and
                                                          a screw to  procline  21|12.
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