re and a polymerization accelerator, wherein the content of the inorganic powder in each paste is 75-85% by weight, and the above-mentioned polymerizable monomer mixtures each contain a monomer of the formula (1): ##STR3## wherein R1 and R2 may be the same or different and each is a hydrogen atom or a methyl, and p is an integer of 1-4, and a monomer of the formula (2): ##STR4## wherein R3 and R4