Department of Endodontics and Restorative Dentistry, School of Dental Medicine, University of Zagreb, Gunduliceva 5, Zagreb, Croatia.
Department of Conservative and Preventive Dentistry, Center for Dental Medicine, University of Zurich, Plattenstrasse 11, Zurich, Switzerland.
Sci Rep. 2021 Jun 3;11(1):11806. doi: 10.1038/s41598-021-91279-z.
The aim of this study was to investigate whether experimental and commercial dental restorative materials with functional fillers can exert a protective anti-demineralizing effect on enamel that is not immediately adjacent to the restoration. Four experimental resin composites with bioactive glass and three commercial restorative materials were investigated. Enamel blocks were incubated in a lactic acid solution (pH = 4.0) at a standardized distance (5 mm) from cured specimens of restorative materials. The lactic acid solution was replenished every 4 days up to a total of 32 days. Surfaces of enamel blocks were periodically evaluated by Knoop microhardness measurements and scanning electron microscopy. The protective effect of restorative materials against acid was identified as enamel microhardness remaining unchanged for a certain number of 4-day acid addition cycles. Additionally, the pH of the immersion medium was measured. While enamel microhardness in the control group was maintained for 1 acid addition cycle (4 days), restorative materials postponed enamel softening for 2-5 cycles (8-20 days). The materials capable of exerting a stronger alkalizing effect provided longer-lasting enamel protection. The protective and alkalizing effects of experimental composites improved with higher amounts of bioactive glass and were better for conventional bioactive glass 45S5 compared to a fluoride-containing bioactive glass. Scanning electron micrographs evidenced the protective effect of restorative materials by showing a delayed appearance of an etching pattern on the enamel surface. A remotely-acting anti-demineralizing protective effect on enamel was identified in experimental composites functionalized with two types of bioactive glass, as well as in three commercial ion-releasing restorative materials.
本研究旨在探讨具有功能性填料的实验性和商业性牙科修复材料是否对与修复体不直接相邻的牙釉质具有保护抗脱矿作用。研究了四种具有生物活性玻璃的实验性树脂复合材料和三种商业修复材料。将牙釉质块在乳酸溶液（pH = 4.0）中孵育，与固化的修复材料样本保持标准化距离（5mm）。每 4 天补充一次乳酸溶液，总共持续 32 天。通过 Knoop 显微硬度测量和扫描电子显微镜定期评估牙釉质块表面。通过确定修复材料对酸的保护作用为在一定数量的 4 天酸添加循环中牙釉质显微硬度保持不变来识别。此外，还测量了浸出液的 pH 值。虽然对照组牙釉质的显微硬度在 1 次酸添加循环（4 天）中保持不变，但修复材料将牙釉质软化推迟了 2-5 次循环（8-20 天）。能够发挥更强碱化作用的材料提供了更持久的牙釉质保护。随着生物活性玻璃含量的增加，实验性复合材料的保护和碱化效果得到改善，且常规生物活性玻璃 45S5 优于含氟生物活性玻璃。扫描电子显微镜图像通过显示在牙釉质表面上出现延迟的蚀刻图案，证明了修复材料的保护作用。两种类型的生物活性玻璃功能化的实验性复合材料以及三种商业离子释放性修复材料均在牙釉质上表现出远程抗脱矿保护作用。
