The effect of seating pressure and powder/liquid ratio of zinc phosphate cement on the retention of crowns.

The effect of three different powder/liquid ratios of one zinc phosphate cement on the early retention of a standard crown on metal and tooth dies was investigated. Two different seating pressures were evaluated. The results indicate that the effect of variation in the powder/liquid was not significant. The part played by the seating force was significant, the higher seating force resulting in a greater force being required for displacement after 1 h. Greater forces of removal were required when tooth dies were used.