Modular 3D printable orthodontic measuring apparatus for force and torque measurements of thermoplastic/removable appliances

The magnitude of forces and moments applied on teeth during orthodontic treatment is crucial to achieve the desired tooth movement. The aim of this study is to introduce a modular 3D printable orthodontic measurement apparatus (M3DOMA), which can be used for measurements of forces and moments acting on teeth during treatment with aligners. The measurement device was characterized regarding signal to noise ratio (SNR) of the sensors, repeatability of measurements, influence of thermoforming, as well as reliability. Forces and moments were evaluated for an activation range of 0.1-0.4 mm, comparing them among different activation patterns with two aligner thicknesses. The sensors exhibited a SNR from 13-33 dB. Repeatability with repeated measurements showed standard deviations <= 0.015 N and 0.769 Nmm. The influence of thermoforming represented by standard deviation of forces ranges from 0.019-0.147 N. The device showed a range of intra class correlation (ICC) for repeated measurements for all sensors from 0.932 to 0.999. Hence the reliability of the device has been proven to be excellent.