Abstract: Objective: To investigate the accuracy of implant bed preparation in mandibular All-on-4 surgery, with help of modified existing robotic positioning marker, by using implant robot system in vitro. Methods: With the assistance of the modified robotic positioning marker, the implant robot system was used to complete the implant bed preparation operation of 20 mandibular All-on-4 implant models. The differences between the actual positions of implant beds and anchor pins and preoperative planning were measured and analyzed, as well as the maximum stress experienced during the drilling process using the drills. Results: There was no significant difference in entry deviation, apex deviation, and angular deviation between implants at different angles (P>0.05). There was no statistical difference between entry deviation and apex deviation within implant groups at different angles, and between entry deviation and apex deviation of screws (P>0.05). During hole preparation, a significant increasing trend in the maximum lateral stress experienced by the milling cutters and pilot drills was observed with increased implant placement angles during implant bed preparation (P<0.05). The maximum lateral stress on the milling cutter was significantly greater than that on the other drills at the same site (upright or tilted), and the maximum lateral stress on the pilot drill was significantly greater than that on the twist drill at the same tilted site (P<0.05). Conclusion: With the assistance of the modified robotic positioning marker, the implant robot technology could be used in the mandibular All-on-4 implant treatment with a high degree of hole preparation accuracy. In addition, during the drilling process, the inclination angle of the implanting site will have a significant impact on the maximum lateral force experienced by the cutters and pilot drills.

Key words: dental implant, robotic surgery, All-on-4, accuracy