McKenna Jill E, Ray Noel J, McKenna Gerald, Burke Francis M
Restorative Dentistry, Cork University Dental School and Hospital, University College Cork, Ireland.
Int J Dent. 2011;2011:679315. doi: 10.1155/2011/679315. Epub 2011 Dec 8.
Aim. To investigate (a) variability in powder/liquid proportioning and (b) effect of variability on diametral tensile strength (DTS), in a zinc phosphate cement. Statistical analyses (α = 0.05) were by Student's t-test in the case of powder/liquid ratio and one-way ANOVA and Tukey HSD for pair-wise comparisons of mean DTS. The Null hypotheses were that (a) the powder-liquid mixing ratios would not differ from the manufacturer's recommended ratio (b) DTS of the set cement samples using the extreme powder/liquid ratios would not differ from those made using the recommended ratio. Methodology. 34 dental students dispensed the components according to the manufacturer's instructions. The maximum and minimum powder/liquid ratios, together with the manufacturer's recommended ratio, were used to prepare samples for DTS testing. Results. Powder/liquid ratios ranged from 2.386 to 1.018. The mean ratio (1.644) was not significantly different from the recommended value of 1.718 (P = 0.189). DTS values for the maximum and minimum ratios were both significantly different from each other (P < 0.001) and from the mean value obtained from the recommended ratio (P < 0.001). Conclusions. Variability exists in powder/liquid ratio for hand dispensed zinc phosphate cement. This variability can affect the DTS of the set material.
目的。研究磷酸锌水门汀中（a）粉液配比的变异性，以及（b）变异性对径向拉伸强度（DTS）的影响。对于粉液比，采用学生t检验进行统计分析（α = 0.05）；对于平均DTS的两两比较，采用单因素方差分析和Tukey HSD检验。无效假设为：（a）粉液混合比与制造商推荐的比例无差异；（b）使用极端粉液比制备的凝固水泥样品的DTS与使用推荐比例制备的样品无差异。方法。34名牙科学生按照制造商的说明调配成分。使用最大和最小粉液比以及制造商推荐的比例来制备用于DTS测试的样品。结果。粉液比范围为2.386至1.018。平均比例（1.644）与推荐值1.718无显著差异（P = 0.189）。最大和最小比例的DTS值彼此之间以及与从推荐比例获得的平均值均有显著差异（P < 0.001）。结论。手工调配的磷酸锌水门汀的粉液比存在变异性。这种变异性会影响凝固材料的DTS。
