College of Dentistry, Imam Abdulrahman Bin Faisal University, Dammam, Saudi Arabia.
Department of Biophysics, Institute for Research and Medical Consultations (IRMC), Imam Abdulrahman Bin Faisal University, Dammam, Saudi Arabia.
J Prosthodont. 2023 Apr;32(4):298-308. doi: 10.1111/jopr.13561. Epub 2022 Jul 22.
To introduce a new technique, denture base layering, for the addition of titanium dioxide nanoparticles (TiO NPs) to polymethylmethacrylate (PMMA) and to investigate the effects of the layering technique on Candida albicans (C. albicans) adhesion and on surface roughness, hardness, translucency, and flexural strength.
In total, 210 heat-polymerized acrylic resin specimens were prepared as discs (15 × 2 mm) for testing C. albicans adhesion (n = 70) and surface roughness, hardness, and translucency (n = 70); and as acrylic plates (65 × 10 × 2.5 mm) for testing flexural strength (n = 70). Specimens were divided into 4 groups: control (n = 30), one-layer (n = 60), double-layer (n = 60), and dotted-layer (n = 60) according to the packing and layering technique. Each group was divided according to the concentration of TiO NPs 1% and 2.5% (n = 10). The control group comprised one layer of unmodified resin. The one-layer group comprised one layer of a mixture of PMMA/TiO NPs packed conventionally. The double-layer group consisted of two different layers packed in two steps, as follows: unmodified resin first, followed by a continuous thin layer of the PMMA/TiO NPs mixture. Similarly, the dotted-layer group consisted of two different layers packed in two steps, as follows: unmodified resin first, followed by a thin layer of the PMMA/TiO NPs. However, the second mixture was added in a dotted manner. The direct culture method for C. albicans adhesion before and after ultraviolet light activation, and surface roughness, hardness, translucency, and flexural strength were measured. An analysis of variance and Tukey's post hoc test were used for data analysis (α = 0.05).
The addition of TiO NPs reduced C. albicans adhesion (p < 0.001). However, no significant difference was found between both concentrations within the same group before and after ultraviolet light activation (p > 0.05), except in the 1% dotted-layer (p = 0.022). Surface roughness and hardness were not affected by the additions of different concentrations of TiO NPs (p = 0.905) and (p = 0.059), respectively. Translucency was significantly reduced in all the groups (p < 0.001) except in the 1% dotted-layer (p = 0.332). Flexural strength decreased as the TiO NPs concentration increased, with the greatest reduction in strength observed in the one-layer group (p < 0.001).
The double and dotted layering techniques were effective in reducing C. albicans adhesion, without affecting surface roughness, hardness, or flexural strength. However, translucency was reduced in all the groups, except the 1% dotted-layer group.
介绍一种新的技术，义齿基托分层，将二氧化钛纳米粒子（TiO NPs）添加到聚甲基丙烯酸甲酯（PMMA）中，并研究分层技术对白色念珠菌（C. albicans）黏附的影响以及对表面粗糙度、硬度、半透明度和弯曲强度的影响。
共制备 210 个热聚合丙烯酸树脂试件，作为用于测试白色念珠菌黏附的圆盘（n = 70）和用于测试表面粗糙度、硬度和半透明度的圆盘（n = 70）；以及作为用于测试弯曲强度的丙烯酸板（n = 70）。根据包装和分层技术，将试件分为 4 组：对照组（n = 30）、单层组（n = 60）、双层组（n = 60）和点状层组（n = 60）。根据 TiO NPs 的浓度，每个组进一步分为 1%和 2.5%（n = 10）。对照组包括一层未改性树脂。单层组包括一层传统方法混合的 PMMA/TiO NPs。双层组由两步分层组成，如下所示：首先是未改性树脂，然后是一层连续的 PMMA/TiO NPs 混合物。同样，点状层组由两步分层组成，如下所示：首先是未改性树脂，然后是一层 PMMA/TiO NPs。然而，第二种混合物以点状方式添加。在紫外线激活前后通过直接培养法测量白色念珠菌黏附，并测量表面粗糙度、硬度、半透明度和弯曲强度。采用方差分析和 Tukey 事后检验进行数据分析（α = 0.05）。
添加 TiO NPs 降低了白色念珠菌黏附（p < 0.001）。然而，在紫外线激活前后，同一组内两种浓度之间没有发现显著差异（p > 0.05），除了 1%点状层（p = 0.022）。不同浓度 TiO NPs 的添加对表面粗糙度和硬度没有影响（p = 0.905）和（p = 0.059）。除 1%点状层外（p = 0.332），所有组的半透明度均显著降低（p < 0.001）。随着 TiO NPs 浓度的增加，弯曲强度降低，单层组的强度降低最大（p < 0.001）。
双层和点状分层技术可有效降低白色念珠菌黏附，而不影响表面粗糙度、硬度或弯曲强度。然而，除 1%点状层组外，所有组的半透明度均降低。
