Compliance monitor for use with removable orthodontic headgear appliances

ORTHODONTIC' THERAPY can be a time-consuming, costly and sometimes stressful procedure for both the orthodontist and the patient (SERGE et at., 1992). Few healthcare disciplines demand as much patient co-operation as successful orthodontics (RUBIN, 1995). Lack of patient co-operation can destroy the best treatment planning and the most promising treatment mechanics (CLEMMER and HAYES, 1979; SAHM et al., 1990). This work relates to removable orthodontic appliances (headgear type) that are designed to produce specific tooth movements by exerting corrective forces on teeth (Fig. I). The capacity of the supporting structures to remodel as the teeth erupt naturally and when pressures are applied artificially makes orthodontic treatment possible. Failure to wear an appliance for the prescribed period results in a reduction in corrective movement of the teeth (BRoErd~AN, 1969). The incorporation of a timing device into such appliances may encourage a measure of patient co-operation, and criteria for successful treatment may be revealed. Several compliance monitors (timing headgears) have been designed and developed, and some have been marketed in the past two decades. The first timing device was described by Northcutt (NORTHCUTT, 1974). It used a timer mechanism which was activated by a simple pressure switch on the neckstrap, but it lost favour with orthodontists because it was easily circumvented by the patients (i.e. patients could place heavy objects on the pressure switch to activate the timer