Experimentation and Simulation of Second Sequential Loop Orthodontic Moment Prediction Modeling

Malocclusion is currently the third largest oral disease for harming people’s health. Fixed appliance technology is the most common and effective malocclusion orthodontic treatment method. And the elastic deformation of the second sequential loop generates orthodontic moment to treat the buccal-lingual tooth deformity. The shape of the second sequential loop can greatly affect the orthodontic moment. However, the design of the archwire depends entirely on the experience of the orthodontic doctors. This treatment is ineffective and may easily hurt patients. To solve these problems, the deflection equation of the second sequential loop around the buccal-lingual direction was obtained, the second sequential loop orthodontic moment prediction model was established to find the relation between the shape of the orthodontic archwire and the orthodontic moment to assist doctors design the proper orthodontic archwire. The orthodontic moment measuring device of the second sequential loop with a six-axis force/torque sensor was designed according to the characteristics of orthodontic moment transmission. The orthodontic moment measuring experiments were conducted with second sequential loops of different parameters. Finally, the effective orthodontic-moment prediction model of the second sequential loop was established by developing the correction factors in order to eliminate the errors. The relative errors between the prediction model and the experiment results ranged between 3.54%–8.72%. The orthodontic moment generating process is simulated through ANSYS. The relative errors between the prediction model and the simulation results ranged between 1.57%–7.08%. The experimental and simulation results verify the validity of the orthodontic moment prediction model of the second sequential loop.