ABSTRACT
PURPOSE: The aim of this preliminary study was to investigate, for the first time, the effects of addition of titania nanotubes (n-TiO2) to poly methyl methacrylate (PMMA) on mechanical properties of PMMA denture base. MATERIALS AND METHODS: TiO2 nanotubes were prepared using alkaline hydrothermal process. Obtained nanotubes were assessed using FESEM-EDX, XRD, and FT-IR. For 3 experiments of this study (fracture toughness, three-point bending flexural strength, and Vickers microhardness), 135 specimens were prepared according to ISO 20795-1:2013 (n of each experiment=45). For each experiment, PMMA was mixed with 0% (control), 2.5 wt%, and 5 wt% nanotubes. From each TiO2:PMMA ratio, 15 specimens were fabricated for each experiment. Effects of n-TiO2 addition on 3 mechanical properties were assessed using Pearson, ANOVA, and Tukey tests. RESULTS: SEM images of n-TiO2 exhibited the presence of elongated tubular structures. The XRD pattern of synthesized n-TiO2 represented the anatase crystal phase of TiO2. Moderate to very strong significant positive correlations were observed between the concentration of n-TiO2 and each of the 3 physicomechanical properties of PMMA (Pearson's P value ≤.001, correlation coefficient ranging between 0.5 and 0.9). Flexural strength and hardness values of specimens modified with both 2.5 and 5 wt% n-TiO2 were significantly higher than those of control (P≤.001). Fracture toughness of samples reinforced with 5 wt% n-TiO2 (but not those of 2.5% n-TiO2) was higher than control (P=.002). CONCLUSION: Titania nanotubes were successfully introduced for the first time as a means of enhancing the hardness, flexural strength, and fracture toughness of denture base PMMA.
Subject(s)
Denture Bases , Dentures , Hardness , Nanotubes , Polymethyl MethacrylateABSTRACT
Objective: The diminished ovarian reserve [DOR] is a condition characterized by a reduction in the number and/or quality of oocytes. This primary infertility disorder is usually accompanied with an increase in the follicle-stimulating hormone [FSH] levels and regular menses. Although there are many factors contributing to the DOR situation, it is likely that many of idiopathic cases have genetic/epigenetic bases. The association between the FMR1 premutation [50-200 CGG repeats] and the premature ovarian failure [POF] suggests that epigenetic disorders of FMR1 can act as a risk factor for the DOR as well. The aim of this study was to analyze the mRNA expression and epigenetic alteration [histone acetylation/methylation] of the FMR1 gene in blood and granulosa cells of 20 infertile women
Materials and Methods: In this case-control study, we analyzed the mRNA expression and epigenetic altration of the FMR1 gene in blood and granulosa cells of 20 infertile women. These women were referred to the Royan Institute, having been clinically diagnosed as DOR patients. Our control group consisted of 20 women with normal antral follicle numbers and serum FSH level. All these women had normal karyotype and no history of genetic disorders. The number of CGG triplet repeats in the exon 1 of the FMR1 gene was analyzed in all samples
Results: Results clearly demonstrated significantly higher expression of the FMR1 gene in blood and granulosa cells of the DOR patients with the FMR1 premutation compared to the control group. In addition, epigenetic marks of histone 3 lysine 9 acetylation [H3K9ac] and di-metylation [H3K9me2] showed significantly higher incorporations in the regulatory regions of the FMR1 gene, including the promoter and the exon 1, whereas tri-metylation [H3K9me3] mark showed no significant difference between two groups
Conclusion: Our data demonstrates, for the first time, the dynamicity of gene expression and histone modification pattern in regulation of FMR1 gene, and implies the key role played by epigenetics in the development of the ovarian function