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6Analysis of movements in tooth removal procedures using robot technology105In previous work, we reported on the forces and torques that were measured in all 6 directions during these procedures [8]. In this study, we focus on the direction, range and speed of movements. For the ease of interpretation of this complex data, the parameter ‘axis dominance’ was developed. In this study, we found the most dominant axis of movement to be around the longitudinal axis of the tooth. It was also around this axis where the highest velocities were found and widest ranges of motion. More dorsally, movements along the buccopalatal or buccolingual axis became more relevant. Movement in mesial or distal angulation seemed less apparent, which is well in line with our clinical experience. A useful comparison to previous literature is difficult since scientific data on this topic is, to our knowledge, non-existing. Most studies concerning analysis of tooth removal have focused on measuring forces and did so in a limited fashion [7]. Some studies distinguished between ‘twisting’ (around the tooth’s axis) and ‘rocking’ (buccolingual or buccopalatal) forces, indirectly describing some sort of movement [3, 14, 15]. What remains, for now, is a comparison of our results to our clinical experience. With rotations around the tooth axis being most prominent and buccopalatal/lingual movements being relatively more important in the dorsal area, this seems to correspond well. A large standard deviation was found in our outcomes, showing significant variance in movements and velocity, even within groups of the same teeth. These findings might be expected, based on clinical experience and has several causes. Firstly, the extent of movement and its direction varies largely on both anatomic factors (i.e. root morphology, amount of roots, presence of adjacent teeth) and patient factors (i.e. bone morphology, mineral density) [14, 16]. Although metadata was present that could partially explain some of this variance, due to the relative small sample size, no valuable correlation to these factors can be made at this point. Further research with a larger data sample could be valuable to determine any influences these factors have on tooth removal strategies. Another relevant factor that affects our results is the variety in surgeons. As experiments were performed by 3 different surgeons an increased variance in our results is to be expected. Especially since the surgeons did not receive any specific instructions or calibration, other than to remove teeth as they would do in a clinical setting. Finally, variance in our results might be caused by the calibration step, which is prone to error. Utmost care was taken to align the straight Tom van Riet.indd 105 26-10-2023 11:59