The goal of the study was to investigate the level of zinc oxide nanoparticles (ZnO NPs) release from polymethyl methacrylate (PMMA)–ZnO nanocomposites (2.5%, 5%, and 7.5% w/w), as well as from the ZnO NPs layer produced on pure PMMA, and the impact of the achieved final ZnO NPs concentration on cytotoxicity, before the potential use as an alternative material for denture bases. The concentration of ZnO nanoparticles released to the aqueous solution of Zn2+ ions was assessed using optical emission spectrometry with inductively coupled plasma (ICP-OES). In the control group (pure PMMA), the released mean for ZnO was 0.074 mg/L and for individual nanocomposites at concentrations of 2.5%, 5%, and 7.5% was 2.281 mg/L, 2.143 mg/L, and 3.512 mg/L, respectively. The median for the ZnO NPs layer produced on PMMA was 4.878 mg/L. In addition, in vitro cytotoxicity of ZnO NPs against the human HeLa cell line was determined through the reduction of 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) dye. The cytotoxicity studies demonstrate that ZnO nanoparticles in the concentrations up to 20 mg/L have no adverse effect on HeLa cells. When compared with the released and cytotoxic concentrations of ZnO NPs, it can be expected that ZnO released from dental prostheses to the oral cavity environment will have no cytotoxic effect on host cells.
Aim: The aim of this study was to investigate the selected properties of zinc oxide- polymethyl methacrylate (ZnO-PMMA) nanocomposites that can influence the microorganism deposition on their surface. Materials and Methods: Non-commercial ZnO-NPs were prepared, characterized and used for the preparation of PMMA nanocomposite. Roughness, absorbability, contact angle and hardness of this new nanomaterial were evaluated. PMMA without ZnO-NPs served as control. Outcomes: Compared to unenriched PMMA, incorporation of ZnO-NPs to 7.5% for PMMA nanocomposite increases the hardness (by 5.92%) and the hydrophilicity. After modification of the material with zinc oxide nanoparticles the roughness parameter did not change. All tested materials showed absorption within the range of 1.82 to 2.03%, which meets the requirements of International Organization for Standardization (ISO) standards for denture base polymers. Conclusions: The results showed no significant deterioration in the properties of acrylic resin that could disqualify the nanocomposite for clinical use. Increased hydrophilicity and hardness with absorbability within the normal range can explain the reduced microorganism growth on the denture base, as has been proven in a previous study.
Porenczuk A, Grzeczkowicz A, Maciejewska I, et al. An initial evaluation of cytotoxicity, genotoxicity and antibacterial effectiveness of a disinfection liquid containing silver nanoparticles alone and combined with a glass-ionomer cement and dentin bonding systems.
Introduction. The aging of the population, as is currently observed, has wide-ranging implications. One of them is an increasing demand for prosthetic treatment of old people with missing teeth using acrylic partial or complete dentures. A denture base made of polymethyl metacrylate (PMMA) creates specific conditions in the oral cavity that predispose patients to develop denture stomatitis complicated by fungal infection. Attempts have recently been made to modify the surface of polymerized acrylic resin by a hydrophilic layer that disrupts the adhesion of microorganisms or to modify the whole chemical composition. In the era of nanotechnology it is reasonable to look for chemical nanocompounds with the intention of incorporating tchem into PMMA and to use their microbiological properties.
Aim of the study. Characteristics of nanoparticles (NPs) of titanium dioxide (TiO2) before their potential use as a modifier for PMMA as an alternative material for denture bases.
Material and methods. TiO2 nanoparticles (Lot No: SHY-179, Promethean Particles Ltd., UK) were used as the experimental material. The average size and size distribution of the crystallites were determined by X-ray powder diffraction (XRD). The density of NPs was determined by helium pycnometer and a specific area using the linear equation form isotherm BET (Brunauer-Emmett-Teller). The average particle size was determined by the calculation results of the specific surface area and density. The NP. morphology is based on images from a scanning electron microscope (SEM).
Results. Tested TiO2 – NPs had an average particle size of about 9 nm, a mean crystallite size of 5-6 nm, a density of 3.16 g/cm3 and a surface area of 215 m2/g. SEM studies showed high homogeneity of the nanoparticles, both in size and shape.
Conclusions. Properties of characterized NPs and the research results of other authors presented in this publication give us a reason to believe that a possible incorporation of NPs into polymethyl methacrylate will activate the antifungal function.
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