Six degree-of-freedom haptic simulation of periodontal pathological changes

Geometric modeling and haptic simulation of pathological changes is an important topic for high-fidelity surgical simulators. In this paper, we introduce a constraint-based six degree-of-freedom (DOF) haptic simulation method incorporating multi-contact friction. We use this method to simulate periodontal operations on typical pathological tissues, including periodontal pocket and two kinds of calculi. A continuous collision detection method based on sphere-trees is proposed to avoid the pop-through phenomenon during tool manipulation against thin objects (such as small sized calculus adhered to the surface of the target tooth). For particle shaped calculus, a friction model is adapted to simulate decreasing frictions during the removal of the calculus. Experiments using a Phantom Premium 3.0 6DOF were carried out to validate the performance of our method. Stable haptic rendering and about 1 kHz update rate was maintained for all the operations, including depth measurement of the periodontal pocket and removal of the invisible block-shaped and particle-shaped calculi.