Objective

Although polymethyl methacrylate (PMMA) is widely used as a dental material, a major challenge of using this substance is its poor antimicrobial (anti-adhesion) effects, which increase oral infections. Here, graphene-oxide nanosheets (nGO) were incorporated into PMMA to introduce sustained antimicrobial-adhesive effects by increasing the hydrophilicity of PMMA.

Methods

After characterizing nGO and nGO-incorporated PMMA (up to 2 wt%) in terms of morphology and surface characteristics, 3-point flexural strength and hardness were evaluated. The anti-adhesive effects were determined for 4 different microbial species with experimental specimens and the underlying anti-adhesive mechanism was investigated by a non-thermal oxygen plasma treatment. Sustained antimicrobial-adhesive effects were characterized with incubation in artificial saliva for up to 28 days.

Results

The typical nanosheet morphology was observed for nGO. Incorporating nGO into PMMA roughened its surface and increased its hydrophilicity without compromising flexural strength or surface hardness. An anti-adhesive effect after 1 h of exposure to microbial species in artificial saliva was observed in nGO-incorporated specimens, which accelerated with increasing levels of nGO without significant cytotoxicity to oral keratinocytes. Plasma treatment of native PMMA demonstrated that the antimicrobial-adhesive effects of nGO incorporation were at least partially due to increased hydrophilicity, not changes in the surface roughness. A sustained antimicrobial-adhesive property against Candida albicans was observed in 2% nGO for up to 28 days.

Significance

The presence of sustained anti-adhesion properties in nGO-incorporated PMMA without loading any antimicrobial drugs suggests the potential usefulness of this compound as a promising antimicrobial dental material for dentures, orthodontic devices and provisional restorative materials.

中文翻译：

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纳米氧化石墨烯掺入PMMA树脂以防止微生物粘附

客观的

尽管聚甲基丙烯酸甲酯（PMMA）被广泛用作牙科材料，但使用该物质的主要挑战是其不良的抗菌（抗粘连）效果，这会增加口腔感染。在此，将氧化石墨烯纳米片（nGO）掺入PMMA中，以通过增加PMMA的亲水性来引入持续的抗微生物粘附作用。

方法

在形态和表面特性方面表征nGO和掺入nGO的PMMA（最高2 wt％）后，评估了三点弯曲强度和硬度。用实验样品确定了4种不同微生物的抗粘连作用，并通过非热氧等离子体处理研究了潜在的抗粘连机理。通过在人工唾液中孵育长达28天来表征持续的抗微生物粘附作用。

结果

对于nGO观察到典型的纳米片形态。将nGO掺入PMMA会使其表面变粗糙并增加其亲水性，而不会影响抗弯强度或表面硬度。在含有nGO的标本中，在人造唾液中暴露于微生物物种1小时后，观察到了抗粘连作用，随着nGO含量的增加而加速，而对口腔角质形成细胞没有明显的细胞毒性。天然PMMA的等离子处理表明，nGO掺入的抗微生物粘附作用至少部分是由于亲水性的提高，而不是表面粗糙度的变化。在2％nGO中观察到长达28天的针对白色念珠菌的持续抗菌粘合特性。

意义

在不添加任何抗微生物药物的情况下，在掺入nGO的PMMA中存在持续的抗粘连特性表明，该化合物作为一种有前景的抗微生物牙科材料，可用于假牙，正畸器械和临时修复材料的潜在用途。