Optimization of grinding parameters in robotic-assisted preparation of cracked teeth based on fracture mechanics: FEA and experiment.

Background And Objectives: If left untreated, cracked teeth can lead to tooth loss, of which the incidence is 70%. Dental preparation is an effective treatment, but it is difficult to meet the clinical requirements when traditionally prepared by dentists. Grinding-based tooth preparation robot (TPR) shows promise for clinical applications to assist dentists. However, current TPR has problems with chipping and crack extension when preparing real teeth.

Methods: We propose a grinding parameter optimization strategy to solve this problem, specifically including preparation depth and direction. Among them, surface morphology observation technology and thermal-mechanical coupling simulation technology are used. Through theoretical modeling, computer simulation techniques and surface morphology experimental studies, different motion parameters are compared and analyzed to derive the optimal preparation parameters.

Results: One of our contributions is to control the preparation depth based on the different material removal methods, and the brittle removal methods and grinding heat during the preparation process were reduced. Another contribution is to derive the stress intensity factor (SIF) at the crack tip for different preparation directions based on multi-grit and thermal-mechanical coupling finite element model for different preparation stages. The preparation direction was directed and crack extension was minimized. Finally, the experimental system of the TPR was constructed. Based on the proposed morphology and preparation direction optimization method, the material removal method during the preparation process can be controlled in plastic removal. Crack extension was also reduced based on different stages of optimized preparation directions. Based on the guided strategy, the TPR can provide safe assisted dentists.

Conclusions: In this work, the preparation parameters of the cracked preparation robot were optimized to enable it to perform the preparation of hard and brittle cracked teeth. The surface morphology met the clinical requirements. Intraoral preparation will be considered in the future to advance the robot toward clinical dental applications.