Diagnostic accuracy of a thermal microsensor for measuring wear time of removable extra-oral orthodontic appliances

Purpose Adherence to orthodontic treatment with removable extra-oral appliances is a key factor influencing treatment outcomes. Objective compliance monitoring systems, such as the Theramon® microsensor, are increasingly used to assess wear time. The aim of this study was to evaluate the diagnostic accuracy of the Theramon® system in detecting wear time of removable extra-oral orthodontic appliances under controlled conditions and to identify the optimal temperature cut-off for maximizing detection accuracy in both winter and summer conditions. Methods A diagnostic accuracy study was conducted on a convenience sample of five healthy volunteers at the Department of XXXX. Two measurement sessions were performed, one in winter and one in summer. The Theramon® microsensor served as the index test. No independent reference standard was available; actual appliance wear time was determined using participant diaries, which were considered representative of true wear time. The optimal temperature cut-off was determined exploratorily during data analysis. Results During the winter session, the optimal temperature cut-off was 29.12°C, with a sensitivity of 0.990 (95% CI: 0.983–0.995) and specificity of 0.999 (95% CI: 0.998–0.999). In the summer session, the optimal cut-off was 32.25°C, with a sensitivity of 0.980 (95% CI: 0.971–0.986) and specificity of 0.971 (95% CI: 0.969–0.974). When data from both sessions were combined, a cut-off of 31°C was selected, resulting in a sensitivity of 0.984 (95% CI: 0.979–0.988) and specificity of 0.969 (95% CI: 0.967–0.971). Conclusions Under controlled conditions, the Theramon® microsensor demonstrated high diagnostic accuracy in monitoring wear time of removable extra-oral orthodontic appliances. These findings support its clinical use for objectively assessing patient adherence to devices such as the facial mask.