Liang Kunneng, Zhou Han, Weir Michael D, Bao Chongyun, Reynolds Mark A, Zhou Xuedong, Li Jiyao, Xu Hockin H K
State Key Laboratory of Oral Diseases, West China Hospital of Stomatology, Sichuan University, Chengdu 610041, China; Department of Endodontics, Periodontics and Prosthodontics, University of Maryland School of Dentistry, Baltimore, MD 21201, USA.
Department of Endodontics, Periodontics and Prosthodontics, University of Maryland School of Dentistry, Baltimore, MD 21201, USA.
Dent Mater. 2017 Jul;33(7):818-829. doi: 10.1016/j.dental.2017.04.016. Epub 2017 May 16.
Patients with dry mouth often have an acidic oral environment lacking saliva that provides calcium (Ca) and phosphate (P) ions. However, there has been no study on dentin remineralization by placing samples in an acidic solution without Ca and P ions. Previous studies used saliva-like solutions with neutral pH and Ca and P ions. Therefore, the objective of this study was to investigate a novel method of combining poly(amido amine) (PAMAM) with a composite of nanoparticles of amorphous calcium phosphate (NACP) on dentin remineralization in an acidic solution without Ca and P ions for the first time.
Demineralized dentin specimens were tested into four groups: (1) dentin control, (2) dentin coated with PAMAM, (3) dentin with NACP nanocomposite, (4) dentin with PAMAM plus NACP composite. Specimens were treated with lactic acid at pH 4 without initial Ca and P ions for 21 days. Acid neutralization and Ca and P ion concentrations were measured. Dentin specimens were examined by scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS) and hardness testing vs. remineralization efficacy.
NACP composite had mechanical properties similar to commercial control composites (p>0.1). NACP composite neutralized acid and released Ca and P ions. PAMAM alone failed to induce dentin remineralization. NACP alone achieved mild remineralization and slightly increased dentin hardness at 21days (p>0.1). In contrast, the PAMAM+NACP nanocomposite method in acid solution without initial Ca and P ions greatly remineralized the pre-demineralized dentin, restoring its hardness to approach that of healthy dentin (p>0.1).
Dentin remineralization via PAMAM+NACP in pH 4 acid without initial Ca and P ions was demonstrated for the first time, when conventional methods such as PAMAM did not work. The novel PAMAM+NACP nanocomposite method is promising to protect tooth structures, especially for patients with reduced saliva to inhibit caries.
口干患者的口腔环境往往呈酸性，且缺乏能提供钙（Ca）和磷（P）离子的唾液。然而，尚未有研究将样本置于不含Ca和P离子的酸性溶液中观察牙本质再矿化情况。以往研究使用的是具有中性pH值且含有Ca和P离子的类似唾液的溶液。因此，本研究的目的是首次探究一种将聚（酰胺胺）（PAMAM）与无定形磷酸钙纳米颗粒（NACP）复合物相结合的新方法，用于在不含Ca和P离子的酸性溶液中对牙本质进行再矿化。
将脱矿牙本质标本分为四组：（1）牙本质对照组；（2）涂有PAMAM的牙本质组；（3）含NACP纳米复合物的牙本质组；（4）含PAMAM加NACP复合物的牙本质组。标本在初始不含Ca和P离子、pH值为4的乳酸溶液中处理21天。测量酸中和情况以及Ca和P离子浓度。通过扫描电子显微镜（SEM）、能量色散光谱（EDS）以及硬度测试来评估牙本质标本的再矿化效果。
NACP复合物的机械性能与商业对照复合物相似（p>0.1）。NACP复合物能中和酸并释放Ca和P离子。单独使用PAMAM未能诱导牙本质再矿化。单独使用NACP在21天时实现了轻度再矿化且牙本质硬度略有增加（p>0.1）。相比之下，在初始不含Ca和P离子的酸性溶液中，PAMAM+NACP纳米复合物方法能使预脱矿牙本质显著再矿化，其硬度恢复至接近健康牙本质的水平（p>0.1）。
首次证明了在初始不含Ca和P离子、pH值为4的酸性环境中，通过PAMAM+NACP实现牙本质再矿化，而诸如PAMAM等传统方法在此情况下无效。新型PAMAM+NACP纳米复合物方法有望保护牙齿结构，尤其对于唾液分泌减少的患者预防龋齿具有重要意义。
