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oxide-based experimental silane primers enhance shear bond strength between resin composite and zirconia. Eur J Oral Sci 2019; 127: 570-576. © 2019 Eur J Oral SciDespite various mechanical and chemical surface-pretreatment methods, long-term bonding of resin composite to dental zirconia (ZrO 2 ) remains a major concern. In this study, graphene oxide (GO) sheets were infused into two commercially available primers and the enclosed mould shear bond strength (EM-SBS) of resin composite to ZrO 2 was evaluated. Twelve fully sintered ZrO 2 blanks were pretreated and randomly allocated to four groups according to the primers used: RelyX (RX); GO blended RelyX (RXGO); Monobond-S (MB); and GO blended Monobond-S (MBGO). The resin composite stubs were bonded onto the pretreated ZrO 2 surfaces and analysed at baseline and after storage in distilled water for 2 and 4 months. The experimental primers blended with GO sheets influenced the surface morphology, visualized as increased surface roughness, and slightly increased the water contact angle measurements. Moreover, the infusion of primers with GO increased the mass fraction (wt%) of carbon and oxygen. The highest EM-SBS values were found for RXGO, with mean (SD) EM-SBS values of 26.4 (3.7) MPa and 21.5 (5.1) MPa after 2 and 4 months of storage, respectively. Infusion of silane primers with nanometre-to micrometre-size GO sheets enhanced the SBS between resin composite and ZrO 2 .

Graphene is an excellent filler for the development of reinforced composites. This study evaluated bone cement composites of graphene oxide (GO) and poly(methyl methacrylate) (PMMA) based on the proliferation of human bone marrow mesenchymal stem cells (hBMSCs), and the anabolic and catabolic effects of the incorporation of GO on osteoblast cells at a genetic level. Surface wettability and roughness were also evaluated at different GO concentrations (GO1: 0.024 wt% and GO2: 0.048 wt%) in the polymer matrix. Fabricated specimens were tested to (a) observe cell proliferation and (b) identify the effectiveness of GO on the expression of bone morphogenic proteins. Early osteogenesis was observed based on the activity of alkaline phosphatase and the genetic expression of the run-related transcription factor 2. Moreover, bone strengthening was determined by examining the collagen type 1 alpha–1 gene. The surface roughness of the substrate material increased following the addition of GO fillers to the resin matrix. It was found that over a period of ten days, the proliferation of hBMSCs on GO2 was significantly higher compared to the control and GO1. Additionally, quantitative colorimetric mineralization of the extracellular matrix revealed greater calcium phosphate deposition by osteoblasts in GO2. Furthermore, alizarin red staining analysis at day 14 identified the presence of mineralization in the form of dark pigmentation in the central region of GO2. The modified GO–PMMA composite seems to be promising as a bone cement type for the enhancement of the biological activity of bone tissue.

The purpose of this laboratory study was to formulate graphene oxide (GO) nano-sheets and characterize composites of homogenously dispersed GO sheets in poly(methyl methacrylate) (PMMA) acrylic resin of two groups, i.e., with 0.025 wt/wt.% GO (GO1-group) and 0.05 wt/wt.% GO (GO2-group). A large array of surface, mechanical and dynamic mechanical properties, including creep, recovery, stress relaxation behaviour and temperature and frequency sweep of the formulated bone cements were further characterized. Analysis of variance test results (p = 0.05, n = 5) indicated that the nanohardness and elastic modulus of the experimental groups were not significantly different from those of the control. Micro-computed tomography results showed high porosity in the experimental groups. The compressive strength significantly increased both in GO1- and GO2-group under dry and wet storage conditions. The dynamic mechanical properties suggest a desirable role of GO in polymerization with PMMA. The produced GO-PMMA composites exhibited the expected characteristics, so their use in developing low-loading bone cement composites appears to be promising.

The objective of this study was targeted to synthesize and characterize a carbon nanotubes (CNTs) incorporated poly(methyl methacrylate) (PMMA)-based denture polymer. Two experimental denture base polymers were fabricated either by incorporating single-walled CNTs (SWCNTs) (SW-group) or multi-walled CNTs (MWCNTs) (MW-group). In both groups, 0.5 wt% of the CNTs were incorporated into MMA monomer. Using a commercially available heat-cured PMMA (Interacryl Hot, Interdent, Opekarniska, Slovenia), a polymer-to-monomer ratio of 3:1 was used to fabricate the specimens (14 × 14 × 3 mm3 in dimensions) of the control group (without CNTs) (C-group) and the experimental groups (either SWCNT–PMMA or MWCNT–PMMA) ( n = 30, N = 90). Physical, mechanical, thermal, and rheological attributes of the tested materials were assessed. The data were statistically analyzed using SPSS version 21.0 (SPSS®, Chicago, IL, USA) and results were explored with one-way ANOVA. Incorporation of CNTs changed the surface morphology and topography of the PMMA specimens. No thermal changes were observed among C-, SW-, and MW-groups. Conversely, the hardness, elastic modulus and wear resistance were improved in both SW-group and MW-group. Additionally, the dynamic mechanical analyzer showed improvement in storage modulus in SW-group, affirming the load transfer capability of SW–PMMA composite. The CNT–PMMA composite might favorably be used as a potential denture base polymer.