To provide a phosphate-based buried material that makes the surface of press ceramics smooth, and a phosphate-based buried material that can be rapidly heated for use of press ceramics, can obtain sufficient curing expansion, and in which the buried material can be easily removed after press molding.SOLUTION: There is provided a dental phosphate-based buried material contains: a powder material that contains (a) 5 to 20 wt.% of magnesium oxide and (b) 8 to 25 wt.% of ammonium primary phosphate； and a liquid material that contains (c) aqueous solution containing cation-treated colloidal silica. The cation treatment is alumina compound treatment, the aqueous solution containing cation-treated colloidal silica contains 0.001 to 0.30 wt.% of alkaline metal in terms of an oxide, and pH of the aqueous solution is 8.0 to 10.0.SELECTED DRAWING: None【課題】プレスセラミックスの表面を滑沢にする燐酸塩系埋没材、及び、プレスセラミックス用として急速加熱が可能であり、十分な硬化膨張が得られ、プレス成型後に埋没材を容易に除去可能な燐酸塩系埋没材の提供。【解決手段】粉材が、酸化マグネシウム5～20wt%、第一燐酸アンモニウム8～25wt%を含み、液材が、(c)カチオン処理されたコロイダルシリカを含む水溶液を含む歯科用燐酸塩系埋没材。カチオン処理がアルミナ化合物処理であり、カチオン処理されたコロイダルシリカを含む水溶液がアルカリ金属を酸化物換算で０．００１～０．３０ｗｔ％含有し、ｐＨ８．０～１０．０である、歯科用燐酸塩系埋没材。【選択図】なし
