| 摘要 |
333,325. Simon, O. May 27, 1929. Cements containing silicates or zinc phosphate.-With dental cements of the silicate or zinc phosphate types, water-repelling substances such as wax, paraffin oil, bitumen are incorporated by the aid of acid or salts of aluminium, calcium, magnesium etc. This may be done in the course of grinding the cement, or when mixing it for use, and may be aided by the use of solvents such as alcohol. Examples: (1) Hydrochloric acid, calcium chloride and paraffin oil are mixed with powdered silicate cement to a paste, which is then mixed with a further quantity of the silicate cement. (2) Castor oil is treated with sulphuric acid, the free acid is neutralized, and the product added with or without water-glass to powdered silicate cement. In the examples quoted the amount of oil etc. in the final product is 5 per cent or less. |
