Abstract:Dental caries, as one of the three major prevention and treatment diseases of human, seriously affects people′s oral health. Tooth restoration is an important method for treating dental caries. Tooth preparation is a necessary treatment link in the oral dental caries restoration process. In traditional tooth preparation process, a large number of repetitive fine adjustments are required, which rely on the manual operations of doctors with rich clinical experience. In this paper, a robot is adopted to assist doctors for tooth preparation, which effectively improves the quality of tooth preparation and the effect of oral treatment. Through analyzing the operating characteristics of the doctor′s preparation process, the specific requirements of the posterior tooth full crown preparation are determined, and the design requirements of the tooth preparation robot are specified. The constraint conditions of surface patches are constructed using the curved surface mapping relationship, then the model points on the curved surface of the preparation tooth are determined. The functional cusp bevel is divided into three curved surfaces according to the adjacent relationship between the teeth and functions. The interpolation of the three curved surfaces is completed based on the NURBS curved surface. According to the curved model points and characteristics of the curved surface patches, the tooth preparation trajectory planning of the tooth preparation robot is realized based on the isoparametric method. The virtual prototype and physical prototype of tooth preparation robot were designed and developed, and the experiment study on tooth preparation was carried out. The maximum relative fixedpoint errors of the feature points in the X, Y and Z directions are 023, 015 and 097 mm, respectively, and the confidence intervals of the system errors are all within 03 mm, stably. The correlation of the random errors of the feature points in different directions is weak, which verifies the correctness of the tooth preparation trajectory planning method and the feasibility of robot tooth preparation. .txt