The physical properties of the low-fusing porcelain contructed by the use of inorganic reagents on the market.

porcelain seems to have much better special quality, abrasion wear resistance, corrosive resistance and so forth, which are considered the most important as dental restorative materials. But on the other side, porcelain materials have several defects at the same time, because they cannot be processed so easily as metallic or synthetic resin materials, and in addition, they have no elasticity in their physical properties and in addition, they have no elasticity in their physical properties and are fragile to an accidental impact. Generally, dental porcelains are classified according to their fusing temperatures in the following three types; high-fusing porcelain (1280•‹-1371 •Ž), medium-fusing porcelain (1093•‹-1260 •Ž) and low-fusing porcelain (871•‹-1066 •Ž), and each type, the main constituents are feldspar (KA1Si/0/, NaAlSiO/), quartz and kaolin, moreover several kinds of metal oxides-such as CaO, B/0/, ZnO, etc., which are added to the main constituents. Since the medium-fusing porcelain and low-fusing porcelain contain so many kinds of constituents, the technique of constructing porcelains of superior physical properties is said to be hardly to acquire, and especially the main constituent, feldspar has to be of natural superior quality; therefore it is very difficult and limited to get. Few reports of basic research on the composition of dental