US Patent 7121825 Tooth positioning appliances and systems

An improved dental appliance system, and methods for using and fabricating the improved appliance, including a polymeric overlay or shell having a teeth-receiving cavity formed therein and a wire mounted on or embedded in the polymeric shell. The dental appliance having the necessary stiffness or strength to firmly secure the appliance on the teeth and provide controlled forces required for repositioning the teeth, until such time as removal of the appliance is desired. The appliance may be configured for use with a removal mechanisim. The removal mechanism undergoes a state change stimulated by an environmental stimulus or environmental switch.