Abstract: In order to produce a dental cast product having the flat surface, by blending a dispersant with a phosphate-based investing material to improve the dispersability of an aggregate powder and a binder powder so as to prevent a agglomeration of the aggregate powder and the binder powder thereby forming a wall surface of an cavity in a mold to be flat, and also to make more various kinds of powders available for the aggregate powder without restriction to quartz, cristobalite and tridymite, the phosphate-based dental investing material comprising a mixed powder including an aggregate powder and a phosphate-based binder powder, and a liquid, with an alkaline metal salt of phosphoric acid being added to at least one of the mixed powder and the liquid.

Abstract: In order to produce a dental cast product having the flat surface, by blending a dispersant with a phosphate-based investing material to improve the dispersability of an aggregate powder and a binder powder so as to prevent a agglomeration of the aggregate powder and the binder powder thereby forming a wall surface of an cavity in a mold to be flat, and also to make more various kinds of powders available for the aggregate powder without restriction to quartz, cristobalite and tridymite, the phosphate-based dental investing material comprising a mixed powder including an aggregate powder and a phosphate-based binder powder, and a liquid, with an alkaline metal salt of phosphoric acid being added to at least one of the mixed powder and the liquid.

Abstract: A method for using dental acrylic resins, the method comprising mixing a liquid monomer of methyl methacrylate with a polymer powder of methyl methacrylate, forming the mixture into an arbitrary shape by molding, filling, applying or other means, and then polymerizing and curing the formed mixture, wherein organic compounds selected from acryloyl morpholine, a coumarone resin, vinyl stearate, polyvinyl acetate, and alcoholic surfactants are previously added to the liquid monomer as a shrinkage controlling agent for lowering a curing shrinkage caused by the polymerization, is disclosed. According to the invention, not only the curing shrinkage rate of the curing shrinkage generated at the time of polymerization can be readily lowered to 0.3% or less, but also the method of the invention can be applied to a denture, a denture base, a casting pattern, fillers or cements as in the conventional techniques.

Abstract: A dental investing material is disclosed which comprises a combination of: (a) quartz and/or cristobalite, (b) a phosphate binder, and (c) aluminous cement, wherein said dental investing material is further added with tridymite and magnesium silicate. The disclosed dental investing material shows minimized expansion during hardening, significant expansion during heating and develops no cracks when heated at a conventional heating rate.

Abstract: A method of making a wax pattern by using a dental gypsum model is provided, which comprises the steps of applying a release agent on said gypsum model, coating on the thus applied surface a coating material which leaves no ash upon incinerated at 700.degree. C., and applying a wax melt on said surface. When the wax melt is applied on the gypsum model, the wax is in no direct contact with the release agent, and it is unlikely that gaps may be formed between the wax pattern and the gypsum model or a pad of the wax pattern may warp; that is, the additional operation so far needed for correcting such warpage can be dispensed with, so making precise casting possible. In addition, the presence of the release agent enables removal of the wax pattern to be done as conventional. Furthermore, when the thus removed wax pattern is invested in a investment material to incinerate the wax pattern, no ash of the above coating material remains in the cavity, so that metal can be cast with no defect.

Abstract: A dental refractory model material comprises as powdery components 5 to 20% by weight of a soluble phosphate, 5 to 20% by weight of magnesium oxide and 10 to 50% by weight of at least one selected from the group of alumina, zirconia, fused quartz, mullite, spinel and cordierite with the balance being crystalline quartz and crystobalite. The refractory model material also includes a liquid component such as a colloidal silica dispersion.