Abstract
The spill-way-more precisely the spill-groove-has always been prepared on the occlusal surface of artificial tooth for decreasing the chewing pressure and making the food flow more easily. But, the flow mechanism in the spill-groove has ever scarcely been elucidated. The author tried to make clear the flow mechanism in the spill-groove by creep and forced compression test for three kinds of viscoelastic materials. In the creep test, the eight types of metal penetrators were used. The results were as follows : (1) In the creep test, the relative strain obtained by a penetrator having a narrower groove was larger than that obtained by a penetrator having a wider groove. (2) A penetrator having a deeper groove gave a higher value of relative strain than a penetrator having a shallower groove. (3) After the groove was perfectly filled with the testing material, the flow of the material in it could hardly be observed. (4) The stress increasing rate (df/dt) decreased with an increase of the groove cross section area, until the material was perfectly filled in the groove. (5) In the forced compression test, a higher penetration rate gave a higher stress value.
