Objective

Previous studies investigated short-term dentin remineralization; studies on long-term dentin remineralization after fluid challenges mimicking fluids in oral environment are lacking. The objective of this study was to develop a long-term remineralization method to via poly(amido amine) (PAMAM) and rechargeable composite containing nanoparticles of amorphous calcium phosphate (NACP) after fluid challenges for the first time.

Methods

NACP composite was immersed at pH 4 to exhaust its calcium (Ca) and phosphate (P) ions, and then recharged with Ca and P ions, to test the remineralization of the exhausted and recharged NACP composite. Dentin was acid-etched with 37% phosphoric acid. Four groups were prepared: (1) dentin control, (2) dentin with PAMAM, (3) dentin with the recharged NACP composite, and (4) dentin with PAMAM plus recharged NACP composite. PAMAM-coated dentin was immersed in phosphate-buffered saline with shaking for 72 days, because there is fluid flow in the mouth which could potentially detach the PAMAM from dentin. Specimens were treated with a cyclic artificial saliva/lactic acid regimen for 35 days.

Results

After 72 days of immersion plus shaking, the PAMAM still successfully fulfilled its mineralization nucleation. The recharged NACP composite still provided acid-neutralization and ion re-release, which did not decrease with increasing the number of recharge cycles. The immersed-PAMAM plus NACP achieved complete dentin remineralization and restored the hardness to that of healthy dentin.

Signifiance

In conclusion, superior long-term remineralization of the PAMAM plus NACP method was demonstrated for the first time. The immersed-PAMAM plus recharged NACP completely remineralized the pre-demineralized dentin, even after prolonged fluid-challenge similar to that in oral environment. The novel PAMAM plus NACP composite method is promising to provide long-term tooth protection and caries inhibition.

中文翻译：

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流体挑战后，通过聚氨基酰胺和可充电磷酸钙纳米复合材料对牙本质进行长期再矿化

客观的

先前的研究调查了短期牙本质再矿化；缺乏在模仿口腔环境中的液体挑战后进行长期牙本质再矿化的研究。这项研究的目的是开发一种长期再矿化方法，以在首次遇到流体挑战后，通过聚（酰胺胺）（PAMAM）和可充电复合材料包含无定形磷酸钙（NACP）纳米颗粒。

方法

将NACP复合材料浸泡在pH 4下以耗尽其钙（Ca）和磷酸盐（P）离子，然后再添加Ca和P离子，以测试耗尽和重新充电的NACP复合材料的再矿化作用。牙本质用37％的磷酸酸腐蚀。制备了四组：（1）牙本质对照，（2）具有PAMAM的牙本质，（3）具有再充电的NACP复合物的牙本质，和（4）具有PAMAM加上再充电的NACP复合物的牙本质。将PAMAM涂层的牙本质浸泡在磷酸盐缓冲液中并摇晃72天，因为口腔中有液体流动，这有可能使PAMAM与牙本质分离。用循环人工唾液/乳酸方案处理标本35天。

结果

经过72天的浸泡和振动后，PAMAM仍成功完成了其矿化成核作用。充电后的NACP复合材料仍然提供酸中和和离子释放，但不会随着充电循环次数的增加而降低。浸泡的PAMAM加NACP可以使牙本质完全矿化，并使硬度恢复到健康的牙本质。

重要性

总之，首次证明了PAMAM加NACP方法的长期长期矿化作用。浸泡后的PAMAM加上再充盈的NACP完全使矿化前的牙本质矿化，即使在类似于口服环境的长时间液体挑战之后也是如此。新颖的PAMAM加NACP复合方法有望提供长期的牙齿保护和龋齿抑制。