PHYSICOCHEMICAL AND BIOLOGICAL PROPERTIES OF REMINERALIZING, POLYMERIC ACP COMPOSITES.
PHYSICOCHEMICAL AND BIOLOGICAL PROPERTIES OF REMINERALIZING, POLYMERIC ACP COMPOSITES.
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发表时间：
2011
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通讯作者：
JM Antonucci;D. Škrtić
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作者：
JM Antonucci;D. Škrtić
无定形磷酸钙(ACP)聚合物复合材料因其具有修复龋损矿物质的潜力和生物相容性，近年来作为新一代生物活性牙科材料在预防牙科、正畸和牙髓治疗等领域受到了广泛关注。ACP填料嵌入聚甲基丙烯酸酯基质，暴露在类似唾液的水环境中，自发转化为热力学稳定的磷灰石，在转化过程中，以持续的方式释放足够水平的再矿化钙和PO4离子，以刺激矿物回收[1-3]。十多年来，我们团队的研究一直集中在结构/组成/性能关系上，以了解各种生物活性ACP填料、其聚合物树脂相和模拟口腔环境之间的相互作用。具体地说，我们努力改善ACP填料在整个聚合物基质中的分散性，并通过微调树脂相来控制复合材料的关键物理化学性能。到目前为止，对ACP复合材料的生物学效应的研究要少得多。聚合反应得到的乙烯基转化率(DVC)是物理化学参数之一，可以方便地用来间接预测材料中残留单体的浸出倾向及其对细胞的潜在有害影响。在这项研究中，评估了基于两种可见光固化甲基丙烯酸酯树脂配方的潜在再矿化ACP复合材料的物理化学和生物学性能，作为正畸粘合剂和根管封闭剂应用于牙科。这两种类型的仿生ACP复合材料都有望在保持理想的再矿化潜力和机械稳定性的同时，在没有过度聚合收缩(PS)和/或聚合收缩应力(PSS)的情况下获得高的DVC。为了验证这一假设，对实验中的正畸和牙髓共聚物及其ACP复合材料进行了DVC、PS和PSS、吸水性、吸湿性、机械强度和离子释放的评估。通过检测材料提取物对成骨样细胞的形态和活性的影响，并与相关的商业对照进行比较，来评估两种制剂的体外细胞毒性。此外，通过1H核磁共振波谱定量评估了牙髓ACP共聚物和复合材料的可浸出性。据推测，由于实验牙髓制剂中获得了高的DVC，因此其可浸出性，进而它们的细胞毒性不会超过商业对照的细胞毒性。
Because of their potential to regenerate mineral lost to tooth decay and their biocompatibility, amorphous calcium phosphate (ACP) polymeric composites have recently attracted attention as a new generation of bioactive dental materials in preventive dentistry, orthodontics and endodontics. Embedded in polymerized methacrylate matrices and exposed to saliva-like, aqueous milieu, ACP fillers convert spontaneously into thermodynamically stable apatite, and during this conversion, release in a sustained manner, sufficient levels of remineralizing Ca and PO4 ions to stimulate mineral recovery [1–3]. For over a decade, research in our group has been focused on structure/composition/property relationships for an appreciation of the interactions between various types of bioactive ACP fillers, their polymeric resin phases and simulated oral environments. Specifically, we strived to improve the dispersion of ACP filler throughout the polymer matrix and control critical physicochemical properties of the composites via fine-tuning of the resin phases. So far, the biological apects of ACP composites were much less explored. One of the physicochemical parameters, the degree of vinyl conversion (DVC) attained upon polymerization, was conveniently used as an indirect predictor of materials’ tendency to leach residual monomers and their potentially harmful effects on cells. In this study, both physicochemical and biological properties of potentially remineralizing ACP composites based on two visible light curable methacrylate resin formulations were evaluated for dental application as orthodontic adhesives and endodontic root canal sealers. Both types of biomimetic ACP composites were expected to attain high DVC without the excessive polymerization shrinkage (PS) and/or polymerization shrinkage stress (PSS) while maintaining desirable remineralizing potential and mechanical stability. To test this hypothesis, the experimental orthodontic and endodontic copolymers and their ACP composites were assessed for DVC, PS and PSS, water sorption, hygroscopic expansion, mechanical strength and ion release. In vitro cytotoxicity of both formulations was evaluated by examining the morphology and viability of osteoblast-like cells exposed to materials’ extracts and compared to the relevant commercial controls. Additionally, leachability of the endodontic ACP copolymers and composites was quantitatively assessed by 1H nuclear magnetic resonance (1H NMR) spectroscopy. It was assumed that, due to the high DVCs attained in the experimental endodontic formulations, the leachability, and in turn, their cytotoxicity will not exceed the cytotoxicity of the commercial control.