Institute of Oral Science, Chung Shan Medical University, Taichung City, Taiwan.
Int Endod J. 2013 Mar;46(3):234-41. doi: 10.1111/j.1365-2591.2012.02112.x. Epub 2012 Aug 17.
To investigate the effect of two solutions differing by pH (7.4 and 4.0) on the physicochemical properties of a radiopaque dicalcium silicate cement.
The cement was prepared by hand-mixing the dicalcium silicate powder with distilled water in a liquid-to-powder ratio of 0.4 mL g(-1) . A total of 253 cement specimens with dimension of 6 mm (diameter) × 3 mm (height) were used. The morphology, weight loss, porosity and diametral tensile strength of the cement were evaluated after soaking in a solution for different time intervals, in addition to pH changes in the cement-immersed solutions.
After soaking in a pH 7.4 solution for 1 day, the particle size of precipitated apatite spherulites on the cement surfaces was greater than that obtained in a pH 4.0 solution. Solution pH did not result in a significant difference (P > 0.05) in diametral tensile strength of cement specimens at the same soaking time-point. On day 30, the sample was associated with a weight loss of 0.8% in a pH 4.0 solution, whereas in a pH 7.4 solution, a weight increase of 0.2% occurred. A greater porosity of the cement soaked in a pH 4.0 was found compared with that in the solution with pH 7.4. Soaking time affected significantly (P < 0.05) the porosity, weight change and strength of the cements in an acidic environment more than at pH 7.4.
High apatite-forming activity and low degradation were the characteristics of a radiopaque dicalcium silicate cement.
研究两种 pH 值（7.4 和 4.0）不同的溶液对放射阻射硅酸二钙水泥理化性能的影响。
将硅酸二钙粉末与蒸馏水以液固比 0.4 mL/g 在手中混合制备水泥。使用总共有 253 个尺寸为 6mm（直径）×3mm（高度）的水泥试件。浸泡在溶液中不同时间间隔后，评估水泥的形态、失重、孔隙率和直径拉伸强度，以及水泥浸泡溶液的 pH 值变化。
浸泡在 pH 值为 7.4 的溶液中 1 天后，水泥表面沉淀的磷灰石球晶的粒径大于在 pH 值为 4.0 的溶液中获得的粒径。在相同浸泡时间点，溶液 pH 值对水泥试件的直径拉伸强度没有显著差异（P＞0.05）。在第 30 天，在 pH 值为 4.0 的溶液中，样品的失重为 0.8%，而在 pH 值为 7.4 的溶液中，重量增加了 0.2%。在 pH 值为 4.0 的溶液中浸泡的水泥的孔隙率较大，而在 pH 值为 7.4 的溶液中浸泡的水泥的孔隙率较小。浸泡时间对酸性环境中的水泥孔隙率、重量变化和强度的影响比在 pH 值为 7.4 时更为显著（P＜0.05）。
放射阻射硅酸二钙水泥的特点是高磷灰石形成活性和低降解。
