REMOVABLE APPLIANCE THERAPY

I.    Indications for Removable Orthodontic Appliances:

      Removable Orthodontic Appliances are often utilized during the course of limited
      tooth movement within primary, mixed or permanent dentitions. They may be
      employed in either upper or lower arches and typically incorporate finger springs
      or elastics as active components.

      Most tooth movement achieved by means of such appliances
      involves tipping actions only: the crown of a tooth will move in the
      direction of the force that is applied with little movement of root
      apex or a tendency for the root apex to move in the opposite
      direction. Clinical applications are therefore limited to those
      situations in which the position of any given tooth to be moved will
      be improved by a tipping movement. If a tooth requiring bodily
      tooth movement (i.e. translation, moving crowns and apices in the
      same direction), is only tipped, it will tend to relapse rather easily.

II.   Active Components:

      Active components of removable Orthodontic appliances include finger springs
             and Orthodontic elastics:

             Finger springs: Finger springs are fashioned of relatively
             small gauge round Orthodontic arch wire (.016”-.022”) in a
             variety of different configurations, depending upon required
             force levels and direction of tooth movement. The
             incorporation of helixes in the finger spring allows tooth
             movement to be accomplished more efficiently. The
             additional length of wire in the helice increases the wire’s
             range, and decreases its stiffness.

      The use of finger springs is most commonly associated with the correction of a
             tooth that is deflected buccally or lingually: a maxillary lateral incisor in
             crossbite is a prime example.

             Elastics: Elastic wear incident to removable appliances is
             most frequently associated with space closure, buccal-
             lingual tipping and antero-posterior tipping. Attachment is
             afforded by means of bonded or banded hooks on those teeth
             to be moved, and eyelets embedded within acrylic portions of
             the appliance.
III.   Retentive Components:

       Beyond active force generating components, removable appliances also require a
             form of retention. Anterior labial bows and posterior clasps are two such
             examples. Where range is a premium requirement of active components,
             stiffness and strength are qualities necessary in retentive components. As
             such, wires of larger diameter are typically employed (.028”-.040”).
             Beyond clasps, other retentive devices which may be employed include
             interproximal spurs and lingual acrylic extensions keyed interproximally.

III.   Advantages/Disadvantages of Removable Appliances:

       When compared to fixed Orthodontic Appliances (those which are
       banded or bonded in place), removable appliances offer both
       advantages and disadvantages. In a general sense, the use of
       removable appliances has dissipated over the course of the past
       several years due to the clinical ease and efficiency of bonding
       techniques. Particular tooth movements that can be accomplished
       with fixed appliances are simply not possible with those that are
       removable. Removable appliances are best suited to those
       situations where gross manipulation of a tooth (or a small group of
       teeth) is warranted, not those in which detailed or precise
       movements are a functional or cosmetic goal.

                             -   oral hygiene is facilitated
                             -   esthetics may be less of a concern
                             -   relatively simple chairside adjustments
                             -   potentially of less expense

                         - easily lost or broken
                         - rather imprecise tooth movement
                         - entirely dependent upon patient cooperation

IV.    Clinical Use:

              A. Fabrication: After an initial clinical examination, the
                 gathering and review of diagnostic records, and
                 consultation with patient and/or parents, most removable
                 appliances require a series of two appointments, each
                 separated by one to two weeks, for their fabrication.

       Appointment #1: Alginate impression from which a working model will be made
      Appointment #2: Placement of appliance with patient

B. Patient Instructions: Although dependent upon the type
   of appliance utilized and particular tooth movement(s) to
   be accomplished, the following guidelines should typically
   be provided to a patient and/or parent:

      Hygiene: Appliances are removed during brushing and
      are cleaned as necessary.

      Wear Schedule: Appliances are typically worn at all
      times except brushing and eating

      Discomfort: Mild discomfort associated with teeth
      actively being moved is to be expected: usually begins
      4-6 hours post appliance activation and may last 3-7

      Speech difficulties: Mild initial difficulties are to be
      expected, but will usually improve over the course of
      one week

C. Clinical Adjustments: After initial placement of a
   removable appliance, treatment progress is usually
   checked on a periodic basis. Dependent upon the nature
   of the active components, adjustments are typically made
   every three to five weeks.

      Appointments are usually brief with the following

            -   Assess progress of tooth movement
            -   Adjust retentive components of appliance as
                need be
            -   Adjust active components of appliance to
                continue light, continuous level of force
            -   Assess patient cooperation

D. Retention: Retention needs after removable appliance
   therapy are directly dependent upon the nature of tooth
   movement which has been accomplished. Most often
   appliances are adjusted such that they are no longer
   providing an active tooth moving force but rather a
   passive presence to maintain the corrections that have
been achieved. Appliance wear is typically decreased to
part-time, most often P.M. hours over the course of as
little as a few months. On those occasions where long
term retention is a consideration, bonded lingual
retainers may be the most efficient and effective option.

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