Chen Mei, Yang Jiaojiao, Li Jiyao, Liang Kunneng, He Libang, Lin Zaifu, Chen Xingyu, Ren Xiaokang, Li Jianshu
College of Polymer Science and Engineering, Sichuan University, Chengdu 610065, China.
State Key Laboratory of Oral Diseases, West China School of Stomatology, Sichuan University, Chengdu 610041, China.
Acta Biomater. 2014 Oct;10(10):4437-46. doi: 10.1016/j.actbio.2014.05.016. Epub 2014 May 27.
In the bioinspired repair process of tooth enamel, it is important to simultaneously mimic the organic-matrix-induced biomineralization and increase the binding strength at the remineralization interface. In this work, a fourth-generation polyamidoamine dendrimer (PAMAM) is modified by dimethyl phosphate to obtain phosphate-terminated dendrimer (PAMAM-PO3H2) since it has a similar dimensional scale and peripheral functionalities to that of amelogenin, which plays important role in the natural development process of enamel. Its phosphate group has stronger affinity for calcium ion than carboxyl group and can simultaneously provide strong hydroxyapatite (HA)-binding capability. The MTT assay demonstrates the low cytotoxicity of PAMAM-PO3H2. Adsorption tests indicate that PAMAM-PO3H2 can be tightly adsorbed on the human tooth enamel. Scanning electron microscopy and X-ray diffraction are used to analyze the remineralization process. After being incubated in artificial saliva for 3weeks, there is a newly generated HA layer of 11.23μm thickness on the acid-etched tooth enamel treated by PAMAM-PO3H2, while the thickness for the carboxyl-terminated one (PAMAM-COOH) is only 6.02μm. PAMAM-PO3H2 can regulate the remineralization process to form ordered new crystals oriented along the Z-axis and produce an enamel prism-like structure that is similar to that of natural tooth enamel. The animal experiment also demonstrates that PAMAM-PO3H2 can induce significant HA regeneration in the oral cavity of rats. Thus PAMAM-PO3H2 shows great potential as a biomimetic restorative material for human tooth enamel.
在牙釉质的仿生修复过程中，同时模拟有机基质诱导的生物矿化并提高再矿化界面的结合强度非常重要。在这项工作中，第四代聚酰胺 - 胺树枝状大分子（PAMAM）用磷酸二甲酯进行修饰，以获得磷酸端基树枝状大分子（PAMAM-PO3H2），因为它具有与釉原蛋白相似的尺寸规模和外围功能，釉原蛋白在牙釉质的自然发育过程中起重要作用。其磷酸基团对钙离子的亲和力比羧基更强，并且可以同时提供强大的羟基磷灰石（HA）结合能力。MTT试验证明了PAMAM-PO3H2的低细胞毒性。吸附试验表明，PAMAM-PO3H2可以紧密吸附在人牙釉质上。使用扫描电子显微镜和X射线衍射分析再矿化过程。在人工唾液中孵育3周后，经PAMAM-PO3H2处理的酸蚀牙釉质上有一层新生成的厚度为11.23μm的HA层，而羧基端基的（PAMAM-COOH）厚度仅为6.02μm。PAMAM-PO3H2可以调节再矿化过程，形成沿Z轴取向的有序新晶体，并产生类似于天然牙釉质的釉柱样结构。动物实验还表明，PAMAM-PO3H2可以在大鼠口腔中诱导显著的HA再生。因此，PAMAM-PO3H2作为人牙釉质的仿生修复材料具有巨大潜力。
