Tooth extraction is a typical process in clinical dental operations. Interactive haptic simulation of tooth extraction may provide a useful tool for dental students to learn the correct force pattern and tool posture to accomplish a safe tooth extraction. In this paper, we extended our previous configuration-based optimization approach to simulate the six Degree-of-Freedom (DoF) haptic interaction process of tooth extraction. A multi-phase model was proposed to simulate progressive changes of the connection strength between the target tooth and its surrounding gingiva. An energy accumulation model was proposed to compute the small-scale rotation and translation of the target tooth under active forces from a dental forceps. The proposed approach could support training of coordinated force and motion control skill required for tooth extraction. Experimental results validated the stability and efficiency of the proposed approach to simulate various force-displacement profiles for extracting diversified target teeth.

The handle-avatar mapping from the handle of a desktop haptic device (i.e., the handle) to the virtual tool (i.e., the avatar) is subject to several uncertainties, including uncertain held positions of the human hand, un-modeled hand position on the virtual tool, and difference between the shape of the virtual tool and that of the physical handle. The influence of these uncertainties on the force/torque fidelity of 6-DOF haptic rendering is analyzed in this paper. A model of force/torque error induced by these uncertainties is introduced to measure the influences under different contact scenarios. A method based on adding a handle-hand avatar to the virtual tool is proposed to reduce the uncertainties and thus to improve simulation fidelity. Psychophysical experiments were carried out. Experiment results show that the subjective feeling of the human operator is consistent with the theoretical analysis results. Most subjects can feel the increase on torque fidelity after using the proposed method.