This thesis presents a new 6 DOF in vitro dental chewing simulator based on a 6-6 spatial parallel kinematics and a parallel robotic implicit position/force hybrid controller to replicate chewing movements and wear formations on dental components, such as crowns, bridges or a full set of teeth. The human mandible, guided by passive structures such as posterior teeth and the two temporomandibular joints moves with up to 6 DOF in Cartesian space. Currently available biaxial operated wear simulators lack the ability to perform these chewing movements. Their lack of sufficient DOF enables them only to replicate the sliding motion of a single occlusal contact point by neglecting rotational movements and the motion along one Cartesian axis. The motion and forces of more than one occlusal contact point cannot accurately be replicated by these instruments. Furthermore, the majority of wear simulators are not suitable to simultaneously control the main wear affecting parameters such as sliding motion and bite forces in the constraint contact phase of the human chewing cycle. It has been shown that such discrepancies between true in vivo and simulated in vitro situation influences the outcome and the quality of wear studies using such approaches. The new developed dental wear simulator can be used for single and multi-occlusal contact testing due to its ability to move with up to 6 DOF. Recorded human mandibular motion and occlusal force data correspond well to previous research. These force and motion data are the reference input of the simulator. Three experimental studies outlined the importance of simultaneous force and position control for in vitro wear studies. These studies show that combined force/position control improves the quality of wear studies and that 6 DOF in vitro simulators are necessary to compare in vitro research to clinical in vivo wear studies. In addition, the experiments demonstrated that the simulator can reliabily perform long-term, realistic material science studies to a high standard of accuracy in motion and force.
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:550313 |
| Date | January 2010 |
| Creators | Raabe, Daniel |
| Publisher | University of Bristol |
| Source Sets | Ethos UK |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
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