Page 104 - Demo

Chapter 6102Axis dominanceAfter translation of the data towards the same tooth frame (Table 1), movement data can be visualized as shown in Fig 4. It shows typical results of the removal of a central upper incisor and an upper first molar from the same cadaver jaw. Fig 4. Visualization of movement data. Data recorded during removal of an upper central incisor (upper graph) and an upper first molar (lower graph). Movement around the longitudinal axis (blue line) was most dominant in the removal of a central upper incisor. Movement around the mesiodistal rotation (green line) was most dominant in removal of an upper first molar. In the upper first molar, rotation around the longitudinal axis was limited in contrast to the central incisor. X-rotation = rotation around the bucco-palatal or lingual axis. Y-rotation = rotation around the mesiodistal axis. Z-rotation = rotation around the longitudinal axis.To determine along what axis most movement took place, the parameter ‘axis dominance’ was developed. It was calculated, or normalized, by dividing the line length of a single axis by the sum of the length of all 3 (Fig 4). The resulting parameter expresses the relative dominance in terms of amount of rotation along each axis. Results per group of teeth are shown in Fig 5. A clear dominance can be seen for rotations around the longitudinal axis of the tooth, especially in the upper frontal region. More dorsally, rotations around the mesial distal axis become more pronounced. Rotations around the buccopalatal or buccolingual axis (mesial/distal angulation) seem less dominant in all teeth. Tom van Riet.indd 102 26-10-2023 11:59