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

BACKGROUND: 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 Experimental and Clinical Medicine, University of Florence. 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.