Effects of preparation techniques on the porosity of acrylic cements.

We investigated four acrylic cement preparation techniques for their effects on cement porosity: hand mixing, pressurization in a pneumatic pistol, centrifugation, and vacuum mixing. All the techniques were tested on three types of cement with different viscosity characteristics. The best results were obtained with vacuum mixing using a newly designed experimental system, yielding porosity reductions of 60-80 percent relative to hand mixing. Vacuum mixing with a commercial system was also effective, but to a somewhat lesser extent. Pressurization and centrifugation had no substantial effect on the overall porosity. Centrifugation led to considerable nonuniformity in the distribution of pores and additives.