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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. Advantages: - oral hygiene is facilitated - esthetics may be less of a concern - relatively simple chairside adjustments - potentially of less expense Disadvantages: - 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 instructions 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 days 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 objectives: - 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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