Resin-modified glass ionomer containing calcium glycerophosphate: physico-mechanical properties and enamel demineralization

Abstract Sources of calcium and phosphate have been added to dental restorative materials to improve their anticaries effect. Objective This study evaluated the effect of adding calcium glycerophosphate (CaGP) to resin-modified glass ionomer cement (RMGIC) on the physico-mechanical properties, ion release, and enamel demineralization. Material and Methods: Specimens were fabricated for each experimental group: RMGIC without CaGP (Control), RMGIC with 1, 3 and 9% CaGP. To determine the release of fluoride (F), calcium (Ca) and phosphorus (P), six specimens were immersed in demineralization and remineralization solutions for 15 days. In another experimental trial, the following physico-mechanical properties were evaluated at time intervals of 1 and 7 days after fabrication: compressive strength (n=12), diametral tensile strength (n=12), surface hardness of material (n=6) and the degree of conversion of monomers (n=8). To study enamel demineralization, specimens (n=12) were attached to enamel blocks and submitted to pH-cycling. Subsequently, surface and cross-sectional hardness and the concentration of F, Ca and P in enamel were determined. Results The addition of CaGP to RMGIC led to higher mean release of F, Ca and P when compared with control (p<0.001). Mechanical properties were within the range of those of the ionomer cements after addition of 1% and 3% CaGP. The degree of conversion did not differ between groups at the 1st and the 7th day (p>0.439). The addition of 3% and 9% CaGP reduced mineral loss and increased F, Ca and P in the enamel when compared with control (p<0.05). Conclusion The addition of 3% CaGP in RMGIC increased the release of F, P and Ca, reduced enamel demineralization, and maintained the physico-mechanical properties within the parameters for this material.

摘要：为改善牙科修复材料的防龋性能，已有研究向其中添加钙与磷的来源物质。目的：本研究旨在评估向树脂改性玻璃离子水门汀（resin-modified glass ionomer cement, RMGIC）中添加甘油磷酸钙（calcium glycerophosphate, CaGP）对其物理机械性能、离子释放特性及牙釉质脱矿情况的影响。
材料与方法：设置如下实验组：未添加CaGP的RMGIC（对照组），以及分别添加1%、3%、9% CaGP的RMGIC。为检测氟（F）、钙（Ca）与磷（P）的释放量，将6个试件置于脱矿与再矿化溶液中浸泡15天。在另一项实验中，于试件制备后1天和7天两个时间点评估以下物理机械性能：抗压强度（n=12）、径向拉伸强度（n=12）、材料表面硬度（n=6）以及单体转化率（n=8）。为研究牙釉质脱矿情况，将12个试件粘贴于牙釉质块上并进行pH循环处理。随后检测牙釉质的表面与截面硬度，以及其中F、Ca、P的浓度。
结果：与对照组相比，向RMGIC中添加CaGP可显著提升F、Ca、P的平均释放量（p<0.001）。当添加1%与3% CaGP时，材料的机械性能处于该类离子水门汀的正常范围之内。在制备后第1天与第7天，各组的单体转化率无显著差异（p>0.439）。与对照组相比，添加3%与9% CaGP可减少矿物流失，提升牙釉质中F、Ca、P的浓度（p<0.05）。
结论：向RMGIC中添加3% CaGP可提升F、P与Ca的释放量，减轻牙釉质脱矿程度，并将该材料的物理机械性能维持在其正常参数范围内。