Abstract
Whether the addition of different antifungal nanoparticles to denture base materials may affect physical or esthetic properties of the resulting nanocomposite is unclear.
The purpose of this in vitro study was to determine how a new method of adding antifungal nanofiller affects the properties of the processed nanocomposite denture base material.
Heat-polymerized acrylic resin specimens were prepared according to each test specification. Zirconium dioxide nanoparticles (ZrO2NPs) and silver nanoparticles (AgNPs) were added in 0.5, 1.0, and 1.5% of acrylic resin powder. The specimens were divided into 2 groups according to the acrylic resin packing method: 1 layer packed conventionally in one step and 2 layers packed in 2 steps, first with unmodified acrylic resin and then by a thin layer of modified acrylic resin before the final closure. The control group was made of unaltered acrylic resin in 1 step. Flexural strength (FS), translucency, and surface roughness (Ra) were measured. A microbial assay was performed by using the direct culture and slide count methods. Three-way ANOVA and Tukey post hoc tests were used to identify statistical differences among groups (α=.05).
The addition of ZrO2NPs and AgNPs in the 1- or 2-layer specimens reduced Candida albicans adhesion (P<.001). In the 1- and 2-layer specimens, FS significantly increased with ZrO2NPs. AgNPs decreased FS only in the 1-layer specimen (P<.001). Surface roughness was not changed for the 1- and 2-layer specimens with ZrO2NPs or the 1-layer specimen with 0.5% AgNPs (P>.05), while other AgNP groups exhibited increased surface roughness (P<.001). AgNPs significantly lowered translucency in the 1- and 2-layer specimens (P<.001), while ZrO2NPs decreased translucency only in the 1-layer specimen (P<.001).
The addition of ZrO2NPs in the double-layer technique decreased Candida adhesion and improved FS without affecting surface roughness, while AgNPs decreased Candida adhesion and FS and increased surface roughness. Both nanofillers decreased the translucency except 0.5% ZrO2NPs, which did not change translucency when applied in 2 layers.