Adjacent surface trajectory planning of robot-assisted tooth preparation based on augmented reality

Dental caries is a common disease affecting the health of humans. Tooth preparation is an essential method for the treatment of dental caries, and its effect determines the quality of dental caries restoration directly. At present, the doctor-patient ratio of dentistry is incredibly unbalanced, and it is challenging to meet the increasing demand for tooth preparation. Besides, it is prone to produce visual deviation and positioning error if the tooth preparation is operated manually by doctors. This paper focuses on the adjacent surface tooth preparation of the full crown. By analyzing the preparation process, the robot body as well as the end-effector are selected. Further, the pose and position between the robot and the tooth are established. Through the inverse calculation and interpolation of the NURBS curve, the robot-assisted trajectory planning of adjacent surface tooth preparation is realized. On the basis of the traditional offline programming method, mobile App "Dental Preparation Assisting Software" is developed based on augmented reality, which can interactively display the planned adjacent preparation curves and preparation information. And the robot can be controlled by the mobile App, which improves the visualization and efficiency of the preparation process. Finally, the experimental system based on the Dobot Magician robot is established, and the robot experiments of adjacent surface tooth preparation are carried out. The maximum relative fixed-point error of each feature point in the XYZ axis is 0.24 mm, 0.29 mm and 0.37 mm, respectively. The confidence interval width of each feature point in the XYZ direction is stable at about 0.31 mm on average, and the correlation between the feature points in the three directional variables is not strong. The proposed method of robot-assisted trajectory planning based on augmented reality for adjacent surface tooth preparation can improve the efficiency of tooth preparation and relieve the pressure of manual tooth preparation within the margin of error, and its feasibility and validity are verified.