Calcium phosphate exhibits excellent biocompatibility, and with particle size in the nanoscale, calcium phosphate nanoparticles (CPNPs) were explored to replace the hydroxyapatite lost in the nanoporous teeth due to dental erosion. CPNPs (2% w/v) colloidally stabilised by sodium citrate were synthesised via co-precipitation. They were characterised in terms of particle size, morphology, crystallinity, Ca/P ratio and calcium ion release. To ensure uniformity of the substrate, hydroxyapatite (HA) discs were examined as an alternative substrate model to enamel. They were eroded in acetate buffer (0.5 M; pH 4.0) at various timepoints (1, 5, 10, 30 min, and 2, 4 h), and their physical differences compared to enamel were assessed in terms of surface microhardness, surface roughness and step height. The remineralisation properties of the synthesised CPNPs on eroded HA discs at different pH levels were investigated. It was established that CPNPs were heterogeneously deposited on the HA discs at pH 9.2, whereas newly precipitated minerals from CPNPs were potentially formed at pH 6.2.

中文翻译：

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磷酸钙纳米粒子作为牙釉质再矿化剂的潜在应用在羟基磷灰石盘上进行测试

磷酸钙表现出优异的生物相容性，并且具有纳米级的粒径，探索了磷酸钙纳米颗粒 (CPNP) 来替代由于牙齿侵蚀而在纳米多孔牙齿中丢失的羟基磷灰石。CPNPs（2％W / V）胶体由柠檬酸钠稳定合成通过共沉淀。它们的特征在于粒度、形态、结晶度、Ca/P 比和钙离子释放。为了确保基材的均匀性，羟基磷灰石 (HA) 圆盘被检查作为搪瓷的替代基材模型。它们在不同时间点（1、5、10、30 分钟和 2、4 小时）在醋酸盐缓冲液 (0.5 M；pH 4.0) 中被侵蚀，并在表面显微硬度、表面粗糙度方面评估它们与牙釉质的物理差异和台阶高度。研究了合成的 CPNP 在不同 pH 水平下腐蚀的 HA 盘上的再矿化特性。已确定 CPNP 在 pH 9.2 时异质沉积在 HA 圆盘上，而来自 CPNP 的新沉淀矿物质可能在 pH 6.2 时形成。