Expansion Screws for Minor Tooth Movement and Space Management

Excellent removable appliances for patients requiring anterior improvement. These appliances provide the desirable features of esthetics and simplicity of adjustment. The patient will become accustomed to the appliance if it is placed without pressure for the first week. Springs are usually adjusted monthly with a variance of one and one-half millimeters between the active and passive positions. The time required for movement as a result of appliance pressure varies between patients. Lack of movement would usually indicate the need for a more extended period of pressure rather than greater pressure. Minimal spring adjustments avoid appliance displacement.

Labial movement

of an individual anterior can result from pressure provided by a small, but effective, expansion screw. The gear is placed immediately lingual to the tooth to be moved. As the gear is activated, the acrylic is displaced labially against the tooth. Reciprocal anchorage is provided by the main body of acrylic and retentive clasping.

Two or more anteriors

can be moved to the labial by selectively sectioning the acrylic. A larger gear may be used depending on available space and number of teeth to be repositioned. The loops on the labial bow can be periodically opened to allow advancement of the anteriors and avoid restriction of movement. Typically, one millimeter of space is provided between the labial bow and the anteriors at each visit of the patient.

Distal movement

of an individual posterior can be effected by positioning the screw as detailed. In this instance, the clasp remains part of the sectioned acrylic, providing sufficient grasp of the tooth necessary to overcome appliance displacement. Depending on survey, bite blocks or planes may be included to enhance retention and/or to remove interferences.

Individual/groups of posteriors

can be moved to the buccal by an expansion screw positioned and sectioned accordingly. When more movement is required on a particular tooth, the acrylic can be removed from the lingual of adjacent posteriors at the outset of treatment. Once the single posterior has advanced sufficiently, all posteriors will continue to move as a unit to complete the case.