Poly(vinylphosphonic acid) glass ionomer cement
AssigneeNational Research Development Corporation
InventorsJohn Ellis, Alan D. Wilson
Life of this patent
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Abstract
A glass ionomer cement composition comprises poly(vinyl phosphonic acid) dissolved in its own mass of water; and (in treble the total mass of the solution) a powder, being glass or MgO or a cement. The powder has to be deactivated so that the setting reaction with the acid is not too fast, and this is achieved either by a raised Si:Al ratio or by heat-treating. The glass contains heavy ions such as La, Ba or Sr.
Claims14
A cement composition, comprising an intimately blended mixture of a water-containing liquid, a cation-crosslinkable polymeric acid containing on average one phosphonic acid group per one to three backbone carbon atoms, and a cation-leachable surgically acceptable glass powder containing Si and Al in the mol proportions 0.6 to 0.2:1 if previously heat-treated, otherwise exceeding 1.6:1, in the mass proportions (1 minus x) polymeric acid:
- (1 minus 5) glass:
- x liquid, where x is from 0.3 to 0.7, said glass containing at least 10% by weight (as the oxide or salt) of a polyvalent metal of atomic number exceeding 37.
A cement composition, comprising an intimately blended mixture of a water-containing liquid, a cation-crosslinkable polymeric acid containing on average one phosphonic acid group per one to three backbone carbon atoms, and a metal oxide powder, in the mass proportions (1 minus x) polymeric acid:
- (1 minus 5) oxide:
- x liquid, where x is from 0.3 to 0.7, wherein the atomic number of said metal exceeds 37, except Cu, Co, Sn, Bi, Pb, Hg, Cd, Y, La or Mo.
Dependencies are inferred from the claim text.