Abstract: Orthodontic path planning is an integral part of a virtual orthodontic system. Aiming at the multi-objective
and high-dimensional path planning problem, an improved multi-particle swarm optimization (PSO) path planning
method was proposed. Firstly, the multi-PSO was utilized to model and design the tooth path planning to solve the
problem of the overly high orthodontic dimension. Secondly, the difficulties in physiological reconstruction of
different types of teeth were considered based on Beta curve and dental arch depth, and the inertia parameter w of
different particle swarms was optimized to refine the orthodontic treatment process of the traditional orthodontic
system. Finally, the upper and lower limits of position updating were modified to narrow the path search range, reduce
the collision during orthodontic process, and optimize the orthodontic effect. The experimental results show that this
method is 38% more efficient than the single particle swarm optimization model, which is more consistent with
clinical orthodontic treatment, and is more likely to achieve the ideal orthodontic effect after treatment.

Key words: orthodontics, path planning, multi-particle swarm optimization, variable step size