Background <p>This study aimed to compare the accuracy and efficiency of implant-site preparation and placement between conventional serial drilling and trephine drilling, with assistance from an implant robot, on varying bone surface inclinations.</p> Methods <p>A total of 80 implants were placed in a standard polyurethane model using the two drilling methods (conventional serial drilling and trephine drilling) with four different bone surface inclinations (0°, 15°, 30°, 45°), resulting in eight sub-groups. The implant robot was utilized for implant-site preparation and placement. The global coronal deviation, global apical deviation, angular deviation, and implant placement time were recorded as outcome measures.</p> Results <p>In line with the experimental objectives, implants were placed using conventional serial drilling and trephine drilling techniques under conditions of different bone surface inclinations. While no significant difference was observed in implant accuracy, the trephine drilling method showed significantly higher implant efficiency.</p> Conclusions <p>Under the present in vitro conditions, implant robot-assisted trephine drilling for implant-site preparation did not compromise implant precision compared with conventional serial drilling and improved implant efficiency. In addition, it may offer the practical advantage of harvesting autogenous bone material.</p>