Measuring 3D-orthodontic actions to guide clinical treatments involving coil springs and miniscrews

The understanding of the phenomena at the base of tooth movement, due to orthodontic therapy, is an ambitious topic especially with regard to the "optimal forces" able to move teeth without causing irreversible tissue damages. To this aim, a measuring platform for detecting 3D orthodontic actions has been developed. It consists of customized load cells and dedicated acquisition electronics. The force sensors are able to detect, simultaneously and independently of each other, the six orthodontic components which a tooth is affected by. They have been calibrated and then applied on a clinical case that required NiTi closed coil springs and miniscrews for the treatment of upper post-extraction spaces closure. The tests have been conducted on teeth stumps belonging to a plaster cast of the patient's mouth. The load cells characteristics (sensor linearity and repeatability) have been analyzed (0.97 < R 2 < 1; 6.3*10 -6 % < STD < 8.8 %) and, on the basis of calibration data, the actions exerted on teeth have been determined. The biomechanical behavior of the frontal group and clinical interpretation of the results are discussed.