Research On Safe Dental Preparation Trajectory Planning Of Robot Based On Personalized Guide Plate

Dental caries is a world-recognized oral public health problem,which is the main cause of periapical periodontitis and gum bleeding.If it is not treated in time,it will cause difficulty in eating and may even threaten the whole body health.Dental preparation,as a key part of restorative dentistry,is a technical operation in which the dentist decays and reshapes the affected teeth by means of high-speed dental handpieces to meet the needs of retention,support,shape,aesthetics and function of the restoration,with the purpose of accurately reproducing the occlusal relationship of the affected caries.However,there is a serious imbalance in the doctor-patient ratio in China,and the traditional manual dental preparation has problems such as repetitive operations and low efficiency.The introduction of robots for the automation of dental preparation requires the precise reconstruction of the patient’s individual teeth.In addition to,dental preparation is a delicate reduction operation that requires the design of auxiliary guides and the consideration of safety issues during the preparation process.In this paper,the following study was conducted to address the problems of robotic dental preparation.In this paper,a heterogeneous homogeneous personalized caries point cloud alignment fusion method based on gingival margin lines is proposed.After the CT reconstruction model and optical scan model are preprocessed,the search strategy of the gingival margin line is proposed for the reconstructed caries model,and the first alignment scheme of the two caries point cloud models is determined.The NURBS curve was used to fit the gingival margin line of the caries,and the quantitative representation of the gingival margin line was completed.The secondary alignment process of the caries point cloud model was completed based on the fitted gingival margin lines.By collapsing and fusing the caries point cloud alignment results,an accurate and complete caries model was finally obtained.We developed the personalized preparation interactive design software and imported the fused patient caries model,the preparation interactive design software can realize the following functions: preparation point interactive capture,triangular surface re-division and reconstruction,preparation offset molding,guide device sweep molding and so on.Considering the diameter of the needle and the relationship of the preparation boundary points,we completed the expansion of the guide device and design the personalized preparation guide plate in geomagic.According to the operation flow of dental preparation,the robot and the terminal of the dental preparation were determined,and the positional relationship between the dental preparation robot and the target caries was established after the forward and inverse solution of the dental preparation robot.The surface fitting and interpolation were done for the interactively designed personalized cavity bottom surface,and the tooth preparation trajectory of the robot was obtained based on the value points of the surface.After analyzing the key technologies commonly used in the Robotics Operations System（ROS）,we introduced the dental preparation robot,the target caries,and the personalized preparation guide in the ROS environment,and designed the corresponding UI interaction for them to build the robotic safe tooth preparation environment.Based on Moveit,we completed the Cartesian space planning,collision detection and tooth preparation posture setting of the tooth preparation robot,and realized the robot safe tooth preparation control.We also applied action communication to establish the preparation status detection server and client respectively to monitor the automatic preparation process of the robot.After the communication between the dental preparation robot and the host computer was successfully established,the fused target caries model and the interactively designed preparation guide were printed and the materials required for the experiment were prepared.Finally,the dental preparation robot was controlled by the host computer to complete the safe preparation experiment.The accuracy and flatness of the robot was checked by selecting the feature points on the personalized preparation,and the feasibility of safe preparation by the robot was confirmed by analyzing the error between the theoretical and actual values of the feature points.