The effect of reduced glutathione on the toxicity of silver diamine fluoride in rat pulpal cells

Abstract Introduction Due to its ability to arrest untreated dental caries, silver diamine fluoride (SDF) has been advocated for indirect pulp capping procedures. However, the high concentrations of silver and fluoride in SDF raise concerns about its biocompatibility to pulpal tissues. Objectives This study aimed to investigate the effect of SDF on the viability, alkaline phosphatase (ALP) activity, and morphology of pulpal-like cells (RPC-C2A) and to evaluate the influence of reduced glutathione (GSH) on SDF-induced cytotoxicity and deposit formation on dentin. Methodology The cytotoxicity of diluted 38% SDF solutions (10-4 and 10-5), with or without the addition of 5 mM or 50 mM GSH, was evaluated at 6 and 24 hours. Cell viability was detected using WST-8 and the effect on ALP activity was performed using an ALP assay kit. Cell morphology was observed using a phase-contrast microscope. Scanning electron microscopy analysis was conducted to evaluate the effect of GSH incorporation or conditioning on SDF-induced deposit formation on dentin discs. Cytotoxicity data were analyzed by two-way analysis of variance (ANOVA) and Tukey post hoc tests (p<0.05). Results There were significant differences between the groups. The results demonstrated that all tested SDF dilutions caused a remarkable cytotoxic effect, while the addition of GSH prevented SDF-induced damage at 6-hour exposure time in the higher dilution of SDF. Dentin treated with plain SDF or GSH-incorporated SDF solution showed deposit formation with occluded dentinal tubules, unlike the other groups. Conclusion SDF severely disturbed the viability, mineralization-ability, and morphology of pulpal-like cells, while controlled concentrations of GSH had a short-term protective effect against SDF-induced damage. GSH showed an inhibitory effect on SDF-induced dentinal deposit formation. Further research is warranted to evaluate the effect of GSH on caries-arresting, anti-hypersensitivity, and antibacterial functions of SDF.

摘要：氟化氨银（silver diamine fluoride, SDF）能够阻滞未治疗的龋病，因此被推荐用于间接盖髓术。然而，SDF中高浓度的银与氟离子引发了学界对其牙髓组织生物相容性的担忧。
研究目的：本研究旨在探讨氟化氨银（SDF）对牙髓样细胞（RPC-C2A）的存活率、碱性磷酸酶（alkaline phosphatase, ALP）活性及形态的影响，并评估还原型谷胱甘肽（reduced glutathione, GSH）对SDF诱导的细胞毒性及牙本质沉积物形成的影响。
研究方法：本研究评估了稀释至10⁻⁴、10⁻⁵的38%氟化氨银溶液（分别添加或不添加5 mM、50 mM GSH）在培养6小时与24小时后的细胞毒性。采用WST-8法检测细胞存活率，使用碱性磷酸酶检测试剂盒检测ALP活性变化，通过相差显微镜观察细胞形态。采用扫描电子显微镜分析GSH添加或预处理对SDF诱导的牙本质圆盘沉积物形成的影响。细胞毒性数据采用双因素方差分析（ANOVA）及Tukey事后检验进行统计分析（P<0.05）。
研究结果：各组间存在显著性差异。结果显示，所有受试SDF稀释液均表现出显著的细胞毒性；而在稀释度更高的SDF组中，添加GSH可在6小时暴露时间内阻断SDF诱导的细胞损伤。与其他组不同，单纯SDF处理或添加GSH的SDF处理的牙本质样本均出现沉积物形成且牙本质小管闭塞。
研究结论：氟化氨银可显著干扰牙髓样细胞的存活率、矿化能力及形态；适宜浓度的GSH对SDF诱导的细胞损伤具有短期保护作用。GSH可抑制SDF诱导的牙本质沉积物形成。未来仍需开展进一步研究，以评估GSH对SDF龋病阻滞、抗牙本质敏感及抗菌功能的影响。