[Elastic modulus of dental porcelains by dynamic method (author's transl)]

Using an equipment with sensitive vibretor-controller oscillater of elactrostatic drive system, we sought for the difference between elastic modulus of various kinds of dental porcelain and elastic modulus by firing method. We examined the relation between temperature of firing and elastic modulus as well. The obtained results are as follows: 1). Elastic modulus of low fusing porcelain of enamel color was 4.32 times 10(11) dyn/cm2 by air firing 3.95 approximately 4.63 times 10(11) dyn/cm2 by vacuum firing. Low fusing of porcelain of dentin color and the one of enamel color had the same elastic modulus. 2). Elastic modulas of high fusing porcelain of enamel color was 3.58 times 10(11) dyn/cm2 by air firing, 3.41 approximately 3.64 times 10(11) dyn/cm2 by vacuum firing. High fusing porcelain of dentin color and the one of enamel color were of the same elastic modulus. 3). Porcelain of opaque color for metal bond was 3.22 times 10(11) dyn/cm2 by air firing 3.97 approximately 4.22 times 10(11) dyn/cm2 by vacuum firing. When dentin color was added to opaque color elastic modulus was low (3.90 times 10(11) dyn/cm2). 4). Alumina porcelain of opaque color was 5.42 times 10(11) dyn/cm2 by air firing, 6.50 approximately 6.80 times 10(11) dyn/cm2 by vacuum firing. When dentin color was added to opaque color elastic modulus was very low (3.90 times 10(11) dyn/cm2). 5). Elastic modulus to various kinds porcelain changes according to temprature of fusing. And the highest elastic modulus is at the temperature which is 50 approximately 100 degrees C lower than final firing temperature.