Federal University of Goiás, Dental School, Restorative Dentistry Area, Goiânia, GO, Brazil.
J Appl Oral Sci. 2010 Dec;18(6):577-84. doi: 10.1590/s1678-77572010000600008.
Clinicians tend to make reductions in glass ionomer power/liquid (P/L) ratios since some materials are difficult to mix and flow into small cavities, grooves or pits. In general, changing the P/L ratio decreases the physical and mechanical properties of conventional glass ionomer cements (GICs) and resin modified glass ionomer cements (RMGICs), but alterations seem to depend on their composition.
To determine the influence of P/L ratio on the radiodensity and diametral tensile strength (DTS) of glass ionomer cements.
There were 2 factors under study: P/L ratio (manufacturer's recommended P/L ratio and a 50% reduced P/L ratio), and materials (Vitro Molar, Vitro Fil, Vitro Cem conventional GICs and Vitro Fil LC, Ortho Glass LC RMGICs. Five 1-mm-thick samples of each material-P/L ratio were produced for radiodensity evaluation. Samples were x-ray exposed onto Digora phosphor plate and radiodensity was obtained using the software Digora for Windows 2.5 Rev 0. For DTS, five (4.0 x 8.0 mm) cylinder samples of each material were tested (0.5 mm/min). Data were subjected to one- and two-way ANOVA (5x2) followed by Tukey's HSD test, or Kruskal-Wallis and Dunn's method. For paired comparisons, t-test or Mann-Whitney test were used (α=0.05).
There was a significant interaction (P=0.001) for the studied factors (materials vs. P/L ratio). Reduced P/L ratio resulted in significantly lower DTS for the RMGICs, but radiodensity was affected for all materials (P<0.05).
Reduced P/L ratio affected properties of the tested glass ionomer cements. RMGICs were more susceptible to lower values of DTS, but radiodensity decreased for all materials following P/L ratio reduction.
由于某些材料难以混合并流入小的腔隙、凹槽或凹坑，临床医生往往会降低玻璃离子体粉液（P/L）比例。一般来说，改变 P/L 比例会降低传统玻璃离子体水泥（GICs）和树脂改性玻璃离子体水泥（RMGICs）的物理和机械性能，但这些变化似乎取决于它们的成分。
确定 P/L 比例对玻璃离子体水泥的放射密度和直径拉伸强度（DTS）的影响。
有 2 个因素在研究中：P/L 比例（制造商推荐的 P/L 比例和降低 50%的 P/L 比例）和材料（Vitro Molar、Vitro Fil、Vitro Cem 传统 GICs 和 Vitro Fil LC、Ortho Glass LC RMGICs）。每种材料-P/L 比例制作 5 个 1 毫米厚的样本用于放射密度评估。将样本暴露于 Digora 荧光板上的 X 射线，并使用 Digora for Windows 2.5 Rev 0 软件获取放射密度。对于 DTS，每种材料制作 5 个（4.0 x 8.0 毫米）圆柱体样本进行测试（0.5 毫米/分钟）。数据采用单因素和双因素方差分析（5x2），然后进行 Tukey HSD 检验，或 Kruskal-Wallis 和 Dunn 方法。对于配对比较，使用 t 检验或 Mann-Whitney 检验（α=0.05）。
研究因素（材料与 P/L 比例）之间存在显著的相互作用（P=0.001）。对于 RMGICs，降低 P/L 比例导致 DTS 显著降低，但所有材料的放射密度均受影响（P<0.05）。
降低 P/L 比例会影响所测试的玻璃离子体水泥的性能。RMGICs 对较低的 DTS 值更敏感，但所有材料的放射密度均随 P/L 比例降低而降低。
