Objectives

For dental resin composites, high translucency is important. Therefore, the aim of the study was to create a biocompatible and highly translucent resin-based composite, and to investigate the effect of material thickness on translucency.

Methods

A biocompatible ORMOCER® resin matrix was reinforced with dental glass powder as fillers. To reach a high translucency, refractive index matching of the matrix and fillers was done in the two ways: (1) Highly refractive ZrO₂ nanoparticles were incorporated into the resin. (2) The resin was modified via addition of 4-Methylthiophenol. The corresponding refractive indices were acquired on an Abbe refractometer (n = 5). In both cases, the dental glass powder was added and translucency of the resulting minifilled and nanohybrid composites were measured using spectral photometry (n = 5). Additionally, the translucency of the experimental composites was determined as a function of specimen thickness in the range 10 μm–2 mm (n = 5). One-way ANOVA was performed to determine the significant differences in various optical parameters among different amounts of modifications and thicknesses at α = 0.05. Furthermore, cytotoxicity tests (extract and direct contact tests) were conducted according to ISO 10993 to classify the biocompatibility of the composites (n = 6).

Results

The translucency values of the composites with 47 wt.-% dental glass powder and a specimen thickness of 2 mm, could be increased from 26% up to 71% by increasing the refractive index of the matrix through incorporating ZrO₂ nanoparticles. Moreover, it can also be increased to 67% via addition of 4-Methylthiophenol. Further results showed that the translucency significantly depended on the sample thickness following an exponential function. The effect of all tested parameters was significant among the materials (p < 0.001). The composites did not show any cytotoxic effect.

Significance

Highly translucent and biocompatible resin composites were developed. They show attractive properties for the use as dental enamel material in direct and indirect restorations.

中文翻译：

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高透明度的牙科树脂复合材料，通过使用二氧化锆纳米粒子的折射率适应性和有机功能化实现。

目标

对于牙科树脂复合材料，高半透明性很重要。因此，该研究的目的是创建一种生物相容性和高度半透明的树脂基复合材料，并研究材料厚度对半透明性的影响。

方法

生物相容性ORMOCER®树脂基体用牙科玻璃粉作为填充剂增强。为了达到高半透明性，通过两种方式完成了基体和填料的折射率匹配：（1）将高折射率的ZrO ₂纳米颗粒掺入树脂中。（2）通过加入4-甲基硫代苯酚。相应的折射率在阿贝折射仪上获得（n = 5）。在这两种情况下，都添加了牙科玻璃粉，并使用分光光度法（n = 5）测量了所得的微填充和纳米复合材料的半透明性。此外，确定了实验复合材料的半透明性与样品厚度在10 μm–2 mm（n = 5）范围内的关系。进行单向方差分析以确定在不同光学量之间不同的修饰量和厚度在α= 0.05时的显着差异。此外，根据ISO 10993进行了细胞毒性测试（提取和直接接触测试），以对复合材料的生物相容性进行分类（n = 6）。

结果

通过掺入ZrO ₂纳米粒子，可以通过增加基质的折射率，将47％（重量）的牙科玻璃粉和2mm样品厚度的复合材料的半透明值从26％提高到71％。此外，还可以通过添加4-甲基硫代苯酚将其增加至67％。进一步的结果表明，半透明性主要取决于遵循指数函数的样品厚度。所有测试参数对材料的影响均显着（p <0.001）。该复合材料没有显示任何细胞毒性作用。

意义

开发了高度透明和生物相容性的树脂复合材料。它们在直接和间接修复中用作牙釉质材料显示出诱人的性能。