In vitro evaluation of a mechanical testing chewing simulator

Objectives. in this in vitro study, the force-profile of a commonly used chewing simulator (Williytec, Munich, Germany) utilizing fixed weights for loading was evaluated. Methods. Using piezoelectric force sensors the maximum and mean values of the applied forces were recorded in three different load configurations in order to determine the repetition accuracy in one test chamber. The variation in resulting forces of the eight test loading-chambers when using three different loads and descending speeds was explored. Results. The simulator showed high load repetition accuracy between the different cycle rates. Significant differences (up to 38.2 +/- 0.4 N) were observed between the different specimen chambers. in addition, the recorded loads were generally both higher (up to 137.5 +/- 0.4 N) and lower than the nominal loads defined by the static weights. The extent of load variation at contact was highly dependent on the descending cross-speed and selected weight. Finally there were also ringing in the load profiles attributed to vibrations of the mechanical setup. Significance. Studies using weight-controlled chewing simulators should consider these effects when reporting results. In addition, calibrations should be performed to check uniformity of tests conditions for each test chamber. (C) 2008 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.