The Effect On Zinc Phosphate Cement Volume Change Of Minute Film Thickness

To understand the influence of minute film thickness on the volume changes after the solidification of zinc phosphate cement. Metal ingot with a highly smooth and clean surface was used to produce zinc phosphate cement into thin plates of different given thicknesses under parallel pressure. Changes in thickness were observed continuously using an inductive micrometer after the adhesive agent solidified. The resulted data were statistically analyzed. After the zinc phosphate cement plate of 10μm and 20μm in thickness solidified, it first shrank and then dilated in volume. The dilation was greater than the shrinkage. Generally, it tended to increase in volume. No more changes were observed after 24 hrs. After the zinc phosphate cement plates of 40μm, 60μm and 80μm in thickness solidified, they first dilated, and then shrank in volume. The dilation was greater than the shrinkage. Generally, it tended to increase in volume. No more changes were observed after 24 hrs. When the thickness was 100μm and 120μm, the plate tended to shrink slowly from its initial solidification through the 7th day. As a permanent adhesive agent for fixing prosthesis, zinc phosphate cement tends to dilate in the clinically applicable sizes, allowing interference fit between the inner surface of the crown and the abutment surface for reinforced mechanic interlock and fixation.