Northwestern University

Bisco Inc.

Steven J Duray

Byoung I Suh

Eugene P Lautenschlager

Richard L Wixson

Jeremy L Gilbert

Peter Monaghan

Methods for reducing the number and/or size of gas bubbles in a material are disclosed. The disclosed methods involve subjecting materials to pressure for a period of time. The methods have been found to be useful in the preparation of dental composites and dental structures prepared from those composites. Materials produced using the disclosed methods can have enhanced structural and/or aesthetic features.

Method of using gas pressure to reduce porosity in composite materials

Orthopedic bone cements of low porosity, prepared by mixing together at least two liquid components under conditions that allow only minimal exposure to air, are disclosed. In a preferred system, each liquid component consists essentially of a solution of a linear (non-crosslinked) polymer or copolymer of methyl methacrylate (PMMA) dissolved in a non-crosslinking methyl methacrylate (MMA) monomer, with one such solution also containing an activator and a polymerization inhibitor and a second solution containing an initiator as well as a polymerization inhibitor. No reinforcing fillers are present, although a small amount (no more than 12% by weight of the total cement composition) of a radiopacifier may be included in the composition. Since polymerization is initiated by mixing together two or more liquid solutions, and such mixing may be performed in a mixing chamber in which no air is required or is introduced during the mixing operation, prior problems of cement porosity and weakness resulting from air entrapment are avoided or greatly reduced while the reliability and reproducibility of the mixing operation are greatly improved.

Bone cement and method of preparation

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Rolling Meadows, IL, United States of America

Steven J Duray