The effect of variability in the powder/liquid ratio on the strength of zinc phosphate cement

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McKenna, Jill E.
Ray, Noel J.
McKenna, Gerald
Burke, Francis M.
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Hindawi Publishing Corporation
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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.
Dentistry materials , Diametral tensile strength , Zinc phosphate cement , Set cement , Powder-liquid cements
Jill E. McKenna, Noel J. Ray, Gerald McKenna, and Francis M. Burke, “The Effect of Variability in the Powder/Liquid Ratio on the Strength of Zinc Phosphate Cement,” International Journal of Dentistry, vol. 2011, Article ID 679315, 4 pages, 2011. doi:10.1155/2011/679315