ORAL PERCEPTION OF HARDNESS IN VISCOELASTIC PRODUCTS

Abstract

ABSTRACT The problem of hardness perception was examined by means of a psycho‐physical approach. The differential sensitivity was studied over a wide range of hardness (approximately 100 to 600 × 10 4 Pa) with products displaying mainly elastic behavior. A series of five silicon elastomer samples were prepared, each series containing 6–8 samples of varying degrees of hardness. The rheological characteristics of these products were measured. Differential threshold and magnitude estimation tests were carried out by 10 subjects who were asked to make hardness comparisons by biting or squeezing the samples. There was no significant difference in sensitivity between molars and incisors as shown by the differential thresholds which varied between 4 and 11% depending on the hardness range. Pressing between the fingers gave less accurate performances than biting. The difference in sensitivity detected by the threshold measurements was not shown in the magnitude estimation tests.