Association between overjet reduction and wear time of a New-T-activator: a retrospective cohort study

The aim of this retrospective cohort study was to investigate the association between New-T-appliance activator wear time, as measured by a Theramon microsensor, and overjet reduction in patients with a Class II Division 1 malocclusion and to determine whether this association is related to age or sex.

This study included patients with a Class II Division 1 malocclusion treated with a New-T-appliance activator equipped with a Theramon microsensor in a private orthodontic practice between 2011 and 2023. Mean daily wear time was recorded using the temperature-sensitive microsensor, while overjet was measured at baseline and during treatment. Multivariable linear regression analysis was performed to evaluate the association between wear time and overjet reduction, with age and sex included as covariates.

In total, 705 patients were included. The daily mean wear time was 8.3 h/day. Statistically significant associations were found between overjet reduction and mean wear time (p < 0.001). Patients younger than 12 years showed significantly greater overjet reduction than older patients. However, no significant sex-related associations were found.

Higher functional appliance wear time was associated with greater overjet reduction. Patients who start orthodontic treatment at a younger age have a higher appliance wear time and greater overjet reduction. These findings suggest that starting orthodontic treatment with functional appliances before the age of 12 could be beneficial. The patient's sex has not been identified as an influencing factor.