Abstract: The purpose of this study is to quantitatively evaluate orthodontic treatment. The forces and moments applied to the teeth during treatment are rarely measured. Therefore, dentists must rely on their own skills, experience, and senses to perform treatment, which may not be sufficient for some patients. To solve this problem, devices have been developed to measure the forces and moments generated in the teeth. However, there are disadvantages, such as the limitation of the direction in which the forces and moments can be measured and the fact that they do not consider the movement of the teeth during treatment. Therefore, we have developed a device that can measure forces and moments in all axes, reproducing the movement of the teeth during treatment. The developed device consists of two teeth model, a force sensor, and a stepping motor. Considering that the teeth move during treatment, this device was incorporated a motor to control the angle of the teeth. A force sensor is used to measure the forces and moments in the three axes applied to the teeth. This device can reproduce the treatment of abnormally tilted teeth until teeth return to normal position. Quantitative evaluation was performed using the device. A comparative study was conducted between the case of treatment with stainless steel wires and the case of treatment with nickel titanium wires. The result showed that nickel titanium wire has many advantages compare the conventional stainless-steel wires. The advantages are agreed with the dentist’s rule of thumb, and the experimental results suggest that this device was able to make a quantitative evaluation of orthodontic treatment.

Keywords: Force and moment measurement device; Movement of teeth; Orthodontic treatment