PROBLEM TO BE SOLVED: To provide high-strength gypsum being a material for a dental model, and having proper hiding power, improved scanning accuracy and little linear expansion at hardening.SOLUTION: The dental gypsum contains 12-40 pts.wt. of a high-refractive index material having ≥1.70 of the refractive index based on 100 pts.wt. of calcium sulphate hemihydrate. The high-refractive index material to be added to a powder material is preferably rutile type titanium oxide made by a sulfuric acid method, rutile type titanium oxide made by a chlorine method, zirconium oxide, aluminum oxide, zirconium silicate, yttrium oxide, zinc oxide, basic carbonate, basic copper carbonate, white lead, lead titanate, zinc telluride, chrome yellow, chromium oxide, aluminum, cadmium oxide, graphite, tungsten, ferric oxide, iron oxide-hydroxide, diiron trioxide, copper oxide, copper sulfate, antimony, barium titanate, silicon, germanium or silicon carbide.COPYRIGHT: (C)2013,JPO&INPIT【課題】歯科用の模型材であって適度な隠蔽性を有し、スキャン精度を向上させ、なおかつ線硬化膨張が少なく、高強度の石膏の提供。【解決手段】硫酸カルシウム半水塩100重量部に対して屈折率が1.70以上の高屈折率材を12~40重量部含む歯科用石膏。粉材に添加する高屈折率材は、硫酸法ルチル型酸化チタン、塩素法ルチル型酸化チタン、酸化ジルコニウム、酸化アルミニウム、ケイ酸ジルコニウム、酸化イットリウム、酸化亜鉛、塩基性炭酸塩、塩基性炭酸銅、鉛白、チタン酸鉛、テルル化亜鉛、黄鉛、酸化クロム、アルミニウム、酸化カドミウム、グラファイト、タングステン、酸化第二鉄、酸化水酸化鉄、三酸化二鉄、酸化銅、硫酸銅、アンチモン、チタン酸バリウム、シリコン、ゲルマニウム、炭化ケイ素が好ましい。【選択図】なし
