Biopex acquires anti-washout properties by adding sodium alginate into its liquid phase.

Biopex sets upon mixing with its liquid phase due to chelate reaction between sodium succinate and calcium phosphate, then gradually transforms to apatite. As a result of apatite formation, set Biopex shows excellent tissue responses and good osteoconductivity. However, Biopex would be washed out when the paste is exposed to body fluid before its setting reaction. Washed out cement causes an inflammatory response. In this investigation, therefore, sodium alginate was added to the liquid phase of Biopex and its effects on washout properties and transformation to apatite were studied. We found that cement remaining ratio, an index of the anti-washout property, of the Biopex increased by increasing the amounts of added sodium alginate to reach 100% when the liquid phase of Biopex contained 0.6% or more sodium alginate. Biopex gradually transformed to apatite regardless of the amount of added sodium alginate at least when the concentration of the sodium alginate in the liquid phase was 1.0% or less. It is concluded therefore, that addition of sodium alginate is very useful for Biopex to acquire the anti-washout property.