Powder enrichment effects on film thickness of zinc phosphate cement.

The effects of powder erichment and subambiant mixing temperatures on the film thickness of three zinc phosphate cements were measured by two methods. A decrease in film thickness accompanied reduced mixing temperatures and standard powder-liquid ratios. Increased powder-liquid ratios with reduced mixing temperatures showed a decreased film thickness when measured according to ADA Material Specification No. 8. Both Fleck's and S. S. White cement showed an increased film thickness when measured by a tapered-die system. Because of the geometry of the preparations, small increases in cement film thickness can be clinically significant when cementing complete veneer crowns.