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US 4,306,913 AGranted
Method for preparing microporous glassy filler grains for dental resin composites
AssigneeAmerican Dental Association Health Foundation
InventorsCurtis P. Mabie, Daniel L. Menis
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Abstract
A microporous filler for dental composite resin restorations has been developed which gives greatly improved finishability, system non-toxicity and x-ray opacification. These fillers are prepared from frits obtained by the low temperature calcination of gelled inorganic "polymers" followed by a pulsed high-heat treatment.
Claims16
A method of preparing internally microporous glassy filler grains for dental resin composites comprising:
- (a) preparing a sol comprised of refractory inorganic oxides including silica, alumina, and at least one non-toxic x-ray opacifying oxide;
- (b) gelling said sol;
- (c) pre-calcining the gel by heating it to a temperature between about 350.degree. C. and about 650.degree. C. for a sufficient period of time to defume it;
- (d) calcining said gel by heating it to a temperature between about 500.degree. C. and about 1000.degree. C. for a sufficient period of time to provide a filler having a median refractive index between about 1.51 and about 1.64 and to densify said gel to a density between about 2.37 and about 3.15 grams per cubic centimeter;
- and
- (e) comminuting before or after calcining.
3 more elements
Dependencies are inferred from the claim text.