Force-profile in Laboratory Chewing Simulation

Methods: A chewing simulator using released weights for loading was tested in this study (Willytec, Munich, FRG). A piezoelectric force sensor (9132 A, Kistler, Winterthur, Switzerland) was used to convert the load application of the chewing simulator into an electrical signal. A sample rate of 10kHz was used. The force-profile was measured in combination of three different loads (1, 5, and 10Kg) and three different descending speeds of the load cells (10, 30, and 55mm/s). So overall nine sets with varying test parameters were examined and the maxima and the means of the applied forces of the simulated chewing cycles were determined.

Results: The measured mean loading forces of a chewing cycle varied from 11.4±0.1N (1Kg at 10mm/s descending speed) to 104.7±0.1N (10Kg at 55mm/s descending speed). The detected maximum loading forces during chewing cycling ranged from 20.1±0.1N (1Kg at 10mm/s descending speed) to 237.2±0.3N (10Kg at 55mm/s descending speed). Therefore, the applied loads exceeded the nominal loads of the weights between 4.7±0.1% and 21.1±0.9% for the mean loading forces and between 49.8±0.1% and 699.0± 10.0% for the maximum loading forces.

Conclusions: The examined chewing simulator Willytec applied much higher loads at loading contact than the nominal loads of the weights suggested. The excessive load was highly dependent on the descending speed and the selected weight. Studies using chewing simulators which use weights for loading should consider these effects when reporting results.