Study on Dental Impression Materials I. Mechanical Properties of Alginate Impression Materials

The author examined accuracy dimensional change and compression tests of alginate impression materials made in Japan. 1) Length change of models was less than 0.1 per cent as compared with prototypes except one product. 2) When alginate impression moulds were exposed in air, they shrank 0.1 per cent in 10 to 20 minutes. 3) When they were immersed in water, they also shrank ; when one of them was immersed in fixing solution, the shrinkage was more remarkable than in water. 4) Under the stress of 1Kg/cm2, strain was 10.2 to 24.0 percent and permanent set over 4.5 per cent.