Bioactive glass composite for orthodontic adhesives - Formation and characterisation of apatites using MAS-NMR and SEM
Bioactive glass composite for orthodontic adhesives - Formation and characterisation of apatites using MAS-NMR and SEM
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DOI：
10.1016/j.dental.2019.02.010
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发表时间：
2019-04-01
期刊：
影响因子：
5
通讯作者：
Wong, F. S. L.
中科院分区：
文献类型：
--
作者：
Al-eesa, N. A.;Karpukhina, N.;Wong, F. S. L.
目标。用魔角旋转核磁共振(MAS-核磁共振)和扫描电子显微镜(SEM)研究新型生物活性玻璃(BAG)-树脂粘结剂在酸性溶液中的溶解和氟磷灰石(FAP)的形成。用新型含氟袋树脂制备袋式复合片(n=90)。将三组样本(n=30)分别浸入pH=7.3(TB)的Tris缓冲液、pH=7的中性人工唾液(AS7)和pH=4的酸性人工唾液(AS4)中，共10个时间点(6h~6个月)。在每个时间点，一半的浸泡盘被粉碎成粉末，并通过固态MAS-核磁共振进行研究。扫描电子显微镜观察，将另一半浸入盘的另一半置入自固化的聚丙烯酸酯中，观察断裂面的情况。MAS-核磁共振结果表明，BAG复合材料在AS4中的降解速度明显快于TB和AS7。浸泡结束时(6个月)，AS4中约80%的玻璃颗粒已经反应形成磷灰石，P-31信号中2.82ppm的尖锐峰证明了这一点，而TB和AS7中的峰更宽。它还显示了氟磷灰石(FAP)形成的证据，在-103ppm处的F-19信号表明，而在-108ppm附近的信号表明氟化钙是由过量的Ca~(2+)和F-形成的，特别是在较长时间的浸泡中。扫描电子显微镜图像证实了袋复合材料在AS4中具有较高的降解速率，并揭示了时间对更多玻璃颗粒溶解的影响。图像还表明，在TB和AS4的玻璃颗粒周围形成了磷灰石，而在AS7中，磷灰石主要形成在磁盘表面上。BAG复合材料表现出对pH变化的智能反应能力，这对防止脱矿和促进再矿化形成更稳定的氟磷灰石具有潜在的临床益处。(C)2019年牙科材料学院。爱思唯尔公司出版，版权所有。
Objectives. To study the dissolution and fluoroapatite (FAP) formation of a new bioactive glass (BAG)-resin adhesive in an acidic solution in reference to neutral solutions, using the magic angle spinning-nuclear magnetic resonance (MAS-NMR) and the scanning electron microscopy (SEM).Methods. BAG composite disks (n = 90) were prepared from, novel fluoride-containing BAG-resin. Three sample groups (n = 30) of the disks were immersed in Tris buffer pH = 7.3 (TB), neutral artificial saliva pH = 7 (AS7) and acidic artificial saliva pH = 4 (AS4) at ten time points ( from 6 h to 6 months). Half of the immersed disks at each time point were crushed into a powder and investigated by the solid state MAS-NMR. SEM studies were undertaken by embedding the other half of the immersed disk in a self-cure acrylic where the fracture surface was imaged.Results. MAS-NMR results show that the BAG composite degraded significantly faster in AS4 compared to TB and AS7. At the end of the immersion period (6 months), around 80% of the glass particles in AS4 had reacted to form an apatite, evidenced by the sharp peak at 2.82 ppm in P-31 signals compared to a broader peak in TB and AS7. It also shows evidence of fluorapatite (FAP) formation, indicated by F-19 signal at -103 ppm, while signal around -108 ppm indicated the formation of calcium fluoride, from the excess Ca2+ and F- especially on longer immersion. SEM images confirm higher degradation rate of the BAG composite in AS4 and reveal the impact of time on the dissolution of more glass particles. The images also indicate apatite formation around the glass particles in TB and AS4, while it forms predominantly over the disk surface in AS7.Significance. BAG composite demonstrate smart reactivity in response to pH change which has a potential clinical benefit against demineralization and promoting remineralisation to form more stable fluorapatites. (C) 2019 The Academy of Dental Materials. Published by Elsevier Inc. All rights reserved.