Orthodontic simulation system with force feedback for training complete bracket placement procedures

Abstract Background A virtual system that simulates the complete process of orthodontic bracket placement can be used for pre-clinical skill training to help students gain confidence by performing the required tasks on a virtual patient. Methods The hardware for the virtual simulation system is built using two force feedback devices to support bi-manual force feedback operation. A 3D mouse is used to adjust the position of the virtual patient. A multi-threaded computational methodology is adopted to satisfy the requirements of the frame rate. The computation threads mainly consist of the haptic thread running at a frequency of >1000Hz and the graphic thread at >30Hz. The graphic thread allows the graphics engine to effectively display the visual effects of biofilm removal and acid erosion through texture mapping. Using the haptic thread, the physics engine adopts the hierarchy octree collision-detection algorithm to simulate the multi-point and multi-region interaction between the tools and the virtual environment. Its high efficiency guarantees that the time cost can be controlled within 1 ms. The physics engine also performs collision detection between the tools and particles, making it possible to simulate paint and removal of colloids. The surface-contact constraints are defined in the system; this ensures that the bracket will not divorce from or embed into the tooth during the adjustment of the bracket. Therefore, the simulated adjustment is more realistic and natural. Results A virtual system to simulate the complete process of orthodontic bracket bonding was developed. In addition to bracket bonding and adjustment, the system simulates the necessary auxiliary steps such as smearing, acid etching, and washing. Furthermore, the system supports personalized case training. Conclusions The system provides a new method for students to practice orthodontic skills.