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4Robot technology in analyzing tooth removal, a proof of concept63Fig. 2: Holding device for upper ja (1) upper jaw, (2) surface plate, (3) support plate, (4) ground plate, (5) axle boxes, (6) clamping arms, (7) clamping bolt, (8) sliding block, (9) clamp axis, (10) front block, (11) clamping nut, (12) top plate of sensor build-up, (13) force/torque sensor, (14) rotation plate, (15) bottom plate, (16) locking boltThe shape of the upper jaw is geometrically unsuitable to fixate (inverted trapezoid shape) and can be very thin at certain points. As is known from facial trauma surgery, other parts of the midface (located just above the upper jaw) have better properties in terms of fixation because of the strength and shape of the bone. This counts for both the paranasal region (besides the nose) and, more lateral, the connection between upper jaw and zygomatic bone (‘zygomatic buttresses). For holding the upper jaw, see Fig. 2, a clamping nut (7) was placed in an angular position relative to grooves on the main plate (4). Tightening the clamping bolt will force the 3D-printed titanium clamping arms (6), which were manufactured through selective laser melting (material: Ti6AI4V-ELI), to push the maxilla (1) downwards and forwards into a 45-degree angle. This way the frontal part of the maxilla, with its strong paranasal zones is fixated underneath a ridge (10). The ridge’s geometry allows the upper jaw to slide slightly under it and prevents it from tilting upwards. Vertical grooves in this ridge minimizes translation from left to right. Sideward motion is further limited by tightening the axle boxes on the clamp axis (5) against the clamping arms. The arms push the strong zygomatic buttresses downwards and inwards. The rough surface of the clamps ensure grip even when remnants of muscle attachments are not completely removed during preparation of the skull. The shape of the clamp’s head is designed to fit the natural shape of the zygomatic buttress, which reduces the risk of iatrogenic fractures during any of the experiments. Compared to the upper jaw, the Tom van Riet.indd 63 26-10-2023 11:59