Objectives

To develop dental composites incorporating fluorapatite (FA) crystals as a secondary filler and to characterise degree of conversion, key mechanical properties and fluoride release.

Methods

FA rod-like crystals and bundles were hydrothermally synthesised and characterised by scanning electron microscopy/energy dispersive X-ray spectroscopy (SEM/EDS), X-ray diffraction (XRD) and ¹⁹F MAS-NMR. Composites were formulated containing BisGMA/TEGDMA/BisEMA and barium-aluminium-silicate glass (0FA). FA crystals were incorporated at 10 (10FA), 20 (20FA), 30 (30FA) and 40 wt% (40FA) maintaining a filler content of 80 wt% (63–67 vol%). Degree of conversion (DC), flexural strength (FS), flexural modulus (FM), fracture toughness (K_1C), Vickers hardness (HV) and 2-body wear were measured. Fluoride release was measured in neutral and acidic buffers.

Results

XRD and ¹⁹F MAS-NMR confirmed that only FA was formed, whilst SEM revealed the presence of single rods and bundles of nano-rods. DC ranged between 56–60% (p > 0.05). FA composites showed lower FM and lower FS (p < 0.05), but comparable wear resistance and HV (p > 0.05) to 0FA. 30FA and 40FA showed similar K_1C to 0FA (p > 0.05), with SEM showing evidence of toughening mechanisms, whereas 10FA and 20FA showed lower K_1C (p < 0.05). FA containing composites released fluoride that was proportional to the amount of FA incorporated (p < 0.05) but only under acidic conditions.

Significance

The addition of FA to the experimental composites reduced strength and stiffness but not the DC, hardness or wear rate. 30FA and 40FA had a higher K_1C compared to other FA groups. Fluoride release occurred under an accelerated acidic regime, suggesting potential as a bioactive ‘smart’ composite.

中文翻译：

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包含各向异性氟磷灰石束和棒的牙科复合材料的开发和表征。

目标

开发含有氟磷灰石（FA）晶体作为辅助填料的牙科复合材料，并表征转化度，关键机械性能和氟化物释放。

方法

水热合成FA棒状晶体和束，并通过扫描电子显微镜/能量色散X射线光谱（SEM / EDS），X射线衍射（XRD）和¹⁹ F MAS-NMR进行表征。配制的复合材料包含BisGMA / TEGDMA / BisEMA和钡铝硅酸盐玻璃（0FA）。FA晶体的加入量为10（10FA），20（20FA），30（30FA）和40 wt％（40FA），保持填充物含量为80 wt％（63-67 vol％）。测量了转化度（DC），弯曲强度（FS），弯曲模量（FM），断裂韧性（K _{1 C}），维氏硬度（HV）和2体磨损。在中性和酸性缓冲液中测量氟的释放。

结果

XRD和¹⁹ F MAS-NMR证实仅形成了FA，而SEM则显示了单个棒和纳米棒束的存在。DC介于56-60％之间（p  > 0.05）。FA复合材料显示出较低的FM和较低的FS（p  <0.05），但与 0FA相比具有相当的耐磨性和HV（p > 0.05）。30FA和40FA的K _{1 C}与0FA相似（p  > 0.05），SEM显示增韧机理的证据，而10FA和20FA的K _{1 C}较低（p  <0.05）。含FA的复合材料释放的氟化物与掺入的FA的量成正比（p <0.05），但仅在酸性条件下。

意义

在实验复合物中添加FA会降低强度和刚度，但不会降低DC，硬度或磨损率。30FA和40FA的K _{1 C}高于其他FA组。氟化物的释放是在加速的酸性条件下发生的，这表明它具有生物活性“智能”复合材料的潜力。