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Objectives This study evaluated the effect of embedding simvastatin (SIM) on the osteoinductive capacity of PLGA + HA/βTCP scaffolds in stem cells from human exfoliated deciduous teeth (SHED). Materials and methods Scaffolds were produced by PLGA solvent dissolution, addition of HA/βTCP, solvent evaporation, and leaching of sucrose particles to impart porosity. Biphasic ceramic particles (70% HA/30% βTCP) were added to the PLGA in a 1:1 (w:w) ratio. Scaffolds with SIM received 1% (w:w) of this medication. Scaffolds were synthesized in a disc-shape and sterilized by ethylene oxide. The experimental groups were (G1) PLGA + HA/βTCP and (G2) PLGA + HA/βTCP + SIM in non-osteogenic culture medium, while (G3) SHED and (G4) MC3T3-E1 in osteogenic culture medium were the positive control groups. The release profile of SIM from scaffolds was evaluated. DNA quantification assay, alkaline phosphatase activity, osteocalcin and osteonectin proteins, extracellular calcium detection, von Kossa staining, and X-ray microtomography were performed to assess the capacity of scaffolds to induce the osteogenic differentiation of SHED. Results The release profile of SIM followed a non-liner sustained-release rate, reaching about 40% of drug release at day 28. Additionally, G2 promoted the highest osteogenic differentiation of SHED, even when compared to the positive control groups. Conclusions In summary, the osteoinductive capacity of poly(lactic-co-glycolic) acid and biphasic ceramic scaffolds was expressively enhanced by embedding simvastatin. Clinical relevance Bone regeneration is still a limiting factor in the success of several approaches to oral and maxillofacial surgeries, though tissue engineering using mesenchymal stem cells, scaffolds, and osteoinductive mediators might collaborate to this topic.

The objective of this study was to develop a replica method for producing zirconia-reinforced bioactive glass (ZRBG) porous structures for bone repair. Four different types of porous structures were produced: zirconia (G1), 58S BG-coated zirconia (G2), zirconia-reinforced BG (G3) and 58S BG-coated zirconia-reinforced BG (G4). A complete characterization of the specimens was performed via SEM-EDS, Archimedes method, 3D X-ray micro-tomography, micro-indentation, compressive strength tests and SBF immersion tests. G3 and G4 specimens presented a BG matrix (~ 33% glassy phase) with dispersed zirconia particles. The porosity of the specimens ranged from 86% up to 93%. BG58S-zirconia groups G3 and G4) exhibited lower YM (38.76 ± 11.20 GPa and 43.49 ± 2.16 GPa) than that of G1 monolithic zirconia specimens (94.39 ± 12.62 GPa), which were more compatible to that of the bone. No significant difference in compressive strength between BG58S-zirconia (G3: 0.41 ± 0.20 MPa; G4: 0.45 ± 0.11 MPa) and zirconia (G1: 0.32 ± 0.11 MPa) was detected observed (p > 0.05). In vitro SBF tests showed a potential bioactivity for ZRBG porous structures.

Grinding wheel content characterization is still mainly based on empirical tests, lacking the necessary scientific approach. To further develop the current existing methodology, this study introduces a method to characterize the grinding wheel structure and content, using microscale X-ray tomography allied with image processing techniques. An X-ray tomography characterization was performed on four different conventional grinding wheels, each containing a specific mixture of electro-fused and sol-gel aluminum oxide abrasives as grits. The grinding wheels were evaluated in terms of volumetric phase fraction, representative elementary volume, phase, and pore size distribution. The results showcased that even though the grinding wheels presented the same manufacturing label (in terms of mechanical properties), the volumetric phase fraction between the grinding wheels was significantly different. This study aggregates the empirical knowledge used to characterize grinding wheels, opening possibilities for academic and industrial research.

The aim of this study is to apply gamma ray transmission (GRT), a non destructive technique, in the structural characterization of low-porosity ceramic samples. GRT technique is based on the attenuation that photons of an incident radiation beam undergo when passing through the material. With this technique the porosity of alumina (Al2O3) and boron carbide (B4C) ceramic samples, was determined. The equipment employed comprises a 241Am (Americium) gamma ray source (59.6 keV and 100 mCi), a 50.8 mm × 50.8 mm NaI (Tl) scintillation detector coupled to a standard Gamma Ray Transmission system and a micrometric automated table for sample movement. The porosity profile of the samples shows a homogeneous porosity distribution, within the spatial resolution of the employed transmission system. The mean porosity values determined for Al2O3 and B4C were 17.8 (±1.3 %) and 3.87 (±0.43 %), respectively. Statistical treatment of these results was performed and showed that the mean porosity values determined by Gamma Ray Transmission technique are the same as those supplied by the manufacturer.