Abstract
The velocity of the first molar was measured while eating various foods in a natural way and investigated in relation to the mechanical properties of the foods eaten. A masseter myograph simultaneously made a measurement for identification of the first bite. A small disk type magnet was placed on the cheek side of the gum of the first molar. The magnetic field vector was measured by a three dimensional Hall probe and converted to the movement of the first molar on mastication. The maximum mastication velocity of the molar at the first bite was found to be 37-74 mm/s depending on the food. The velocity decreases as the Young's modulus of the tested food increases. Changes in the velocity of the molar from the beginning of mastication to swallowing were assessed for 22 kinds of food. Then the foods were divided into three groups. (A) Mastication velocity changes little while chewing, then decreases for bolus preparation. (B) Chewing velocity increases gradually at the initial stage of chewing. (C) Initial fast mastication velocity decreases steadily but evenly.
