Peer-Reviewed Journal Details
Mandatory Fields
McKenna J, Ray N, McKenna G, Burke FM;
International Journal of Dentistry
The effect of variability in the powder/liquid ratio on the strength of zinc phosphate cement
Optional Fields

Aim:  To investigate (a) variability in powder/liquid proportioning (b) effect of the extremes of any such variability on diametral tensile strength (DTS), in a commercial zinc phosphate cement. Statistical analyses (a = 0.05) were by Student¿s t-test in the case of powder/liquid ratio and one-way ANOVA and Tukey HSD for for pair-wise comparisons of mean DTS. The Null hypotheses were that (a) the powder-liquid mixing ratios observed would not differ from the manufacturer¿s recommended ratio (b) DTS of the set cement samples using the extreme powder/liquid ratios observed would not differ from those made using the manufacturer¿s recommended ratio.

Methodology:  Thirty-four undergraduate dental students dispensed the components according to the manufacturer¿s instructions. The maximum and minimum powder/liquid ratios (m/m), together with the manufacturer¿s recommended ratio (m/m), were used to prepare cylindrical samples (n = 3 x 34) for DTS testing.

Results:  Powder/liquid ratios ranged from 2.386 to 1.018.The mean ratio (1.644 (341) m/m) was not significantly different from the manufacturer¿s recommended value of 1.718 (p=0.189). DTS values for the maximum and minimum ratios (m/m), respectively, were both significantly different from each other (p<0.001) and from the mean value obtained from the manufacturer¿s recommended ratio (m/m) (p<0.001).

Conclusions:  Variability exists in powder/liquid ratio (m/m) for hand dispensed zinc phosphate cement. This variability can affect the DTS of the set material.

Grant Details