advancement of the mandibular position during the treatment of Class II Division I malocclusions.
The system features the incorporation of stainless steel screws with conical heads into the blocks of the upper appliance, to provide the inclined plane effect. Advancement is carried out at the chairside, by the addition of acetal spacers between the screw heads and the upper blocks.
Currently, advancement of Twin Block Appliances requires the time consuming addition of cold curing acrylic at the chairside, or alternative laboratory modification, whereby the patient can be without the appliance for some time.
The Screw Advancement System provides simple, quick, accurate and safe chairside progressive advancement, as well as improving the clinical flexibility of the appliance, and enhancing patient acceptance in cases where mandibular protrusion is limited initially.
Chairside Advancement Procedure: Once the Twin Block has been worn sufficiently to achieve the initial degree of overjet reduction, additional advancement can be made at subsequent visits, by simply removing the advancement screws, and inserting spacers between the screw heads and the block faces. Advancement as much as 6mm can be achieved by using the standard 12mm advancement screws. For greater advancements, the longer 16mm or 20mm screws are recommended. In this way, a gradual reduction of the overjet can be achieved, and a degree of overcorrection obtained if required. The degree of each subsequent advancement can be individualised for each patient with mandibular dental asymmetry. It is possible to advance one side more than the other to obtain centreline correction.
Kit includes:
20 x 16mm advancement screws
20 x 20mm advancement screws
20 x 2mm spacers
20 x 3mm spacers
20 x 4mm spacers
2 x advancement screwdrivers.