Development of 6-Axis Orthodontic Force and Moment Sensing Device for Decreasing Accident of Orthodontic Treatment *

The purpose of this study is to develop the sensing device which measures three-axis force and three-axis moment for reducing the number of accident in orthodontic treatment. The device is necessary for adequate quantitative evaluation of orthodontic forces during orthodontics. The developed sensing device is composed of six-axis force sensors, tooth models, and arms for connecting sensors and tooth models. The developed device simulates rows of teeth in orthodontic operation and measures $14 \times 6$ axes force and moment from tooth models simultaneously. The averages of the difference of force and moment to theoretical values in each direction are 1.78 % (0.043 N) and 2.72 % (0.60 Nmm) respectively. The average moment applying couple forces is 17.1 % (0.81 Nmm). Then the device is able to measure more accurately as the value of the moment was larger. Therefore using our proposed device, we can conduct the orthodontic treatment which dentition moves large for attaching the rail of wire to the teeth.