Page 102 - Demo

Chapter 6100Calibration and reference frame The location and orientation of each tooth was calibrated before the start of an experiment. This step was essential to determine position and orientation of the tooth. It allowed for translation of the movements toward clinically relevant dimensions. The reference frames for all teeth in both upper and lower jaw were identical and can be found in Fig. 1 and 2. The translation of movement data to a single reference frame enabled us to group ‘mirrored’ sets of teeth, for example the first premolars on the upper jaw (14 and 24) or lower second incisor (32 and 42). This was done so to create larger groups and to ease the interpretation of our results. For the calibration step, a straight periosteal elevator was mounted in the forceps-holding device and positioned parallel to the expected axis of each tooth and on top of the center of each crown. The flat part of the elevator pointed towards the lingual or palatal side. A mathematical translation was performed for each of the dental extraction forceps to align the axis according to the tooth frames (Table 1). The expected rotational center of the teeth was estimated 2mm below the center of the crown, as pointed out by the calibration tool. Table 1: tooth reference frame after mathematical translation Axis Positive values Negative valuesRotation around the bucco-palatal/lingual (X-)axis Mesial angulation Distal angulationRotation around the mesiodistal axis (Y-)axis Buccoversion Palatoversion / LinguoversionRotation around the longitudinal (Z-)axis Mesiopalatal / Mesiolingual Mesiobuccal Data availabilityThe processed data required to reproduce our findings are available to download from https://www.doi.org (digital object identifier: 10.4121/20485383).ResultsOverview of experiments A total of 127 experiments were performed on seven fresh-frozen Caucasian specimens. In 110 (86.6%) of these experiments full data was successfully recorded. The main reason (n = 8, 6.3%) for failure of experiments was insufficient fixation of the jaw causing displacement during the experiments, potentially leading to incorrect measurements. Other reasons were fracture of the teeth (n = 5, 3.9%), robot or software Tom van Riet.indd 100 26-10-2023 11:59