GYPSUM-BASED MOLD MATERIAL FOR DENTAL USE

PROBLEM TO BE SOLVED: To obtain the subject mold material convertible into a muddy form and capable of preparing a model and, in the process, eliminating the necessity for applying a separating agent onto a boundary surface not only with a wax pattern but also with an impression, etc., by using a silicone oil as a mold releasing agent of an anhydrite powder for dental use. SOLUTION: This mold material is obtained by adding and mixing (A) an anhydrite powder for dental use with (B) a silicone oil as a mold release agent in an amount of 0.01-1 wt.% based on the component A. The component B is a silicone oil good in mold releasability such as dimethyl silicone oil and preferably having about 0.8-1.2 specific gravity (at 25 deg.C). Furthermore, the ingredient B can be dissolved in an organic solvent for use. The mold material is capable of retaining a powdery state similar to that of a conventional anhydrite powder for the dental use. An adequate amount of water, e.g. that in an amount of 17-23 pts.wt. based on 100 pts.wt. of the powder can be added thereto to provide a muddy state, which can be molded into an optional shape and hardened to prepare a gypsum model.