The capability of electrical stimulation (ES) in promoting bone regeneration has already been addressed in clinical studies. However, its mechanism is still being investigated and discussed. This study aims to investigate the responses of macrophages (J774A.1) and pre‐osteoblasts (MC3T3‐E1) to ES and the faradic by‐products from ES. It is found that pH of the culture media was not significantly changed, whereas H2O2 concentration was increased by 3.6 and 5.4 µM after 1 and 2 hours of ES, respectively. The upregulation of Bmp2 and Spp1 mRNAs was observed after 3 days of stimulation, which is consistent among two cell types. It is also found that Spp1 expression of macrophages was also enhanced by faradic by‐products. Osteogenic differentiation of pre‐osteoblasts was not observed during the early stage of ES as the level of Runx2 expression remains unchanged. However, cell proliferation was impaired by the excessive current density from the electrodes, and also faradic by‐products in the case of macrophages. This study shows that macrophages could respond to ES and potentially contribute to the bone formation alongside pre‐osteoblasts. The upregulation of Bmp2 and Spp1 expressions induced by ES and faradic by‐products could be one of the mechanisms behind the electrically stimulated osteogenesis.
Applying electrical stimulation (ES) could affect different cellular mechanisms, thereby producing a bactericidal effect and an increase in human cell viability. Despite its relevance, this bioelectric effect has been barely reported in percolated conductive biopolymers. In this context, electroactive polycaprolactone (PCL) scaffolds with conductive Thermally Reduced Graphene Oxide (TrGO) nanoparticles were obtained by a 3D printing method. Under direct current (DC) along the percolated scaffolds, a strong antibacterial effect was observed, which completely eradicated S. aureus on the surface of scaffolds. Notably, the same ES regime also produced a four-fold increase in the viability of human mesenchymal stem cells attached to the 3D conductive PCL/TrGO scaffold compared with the pure PCL scaffold. These results have widened the design of novel electroactive composite polymers that could both eliminate the bacteria adhered to the scaffold and increase human cell viability, which have great potential in tissue engineering applications.
Electrical stimulation (ES) has potential to be an effective tool for bone injury treatment in clinics. However, the therapeutic mechanism associated with ES is still being discussed. This study aims to investigate the initial mechanism of action by characterising the physical and chemical changes in the extracellular environment during ES and correlate them with the responses of mesenchymal stem/stromal cells (MSCs). Computational modelling was used to estimate the electrical potentials relative to the cathode and the current density across the cell monolayer. We showed expression of phosphorylated ERK1/2, c-FOS, c-JUN, and SPP1 mRNAs, as well as the increased metabolic activities of MSCs at different time points. Moreover, the average of 2.5 μM of H2O2 and 34 μg/L of dissolved Pt were measured from the electrically stimulated media (ES media), which also corresponded with the increases in SPP1 mRNA expression and cell metabolic activities. The addition of sodium pyruvate to the ES media as an antioxidant did not alter the SPP1 mRNA expression, but eliminated an increase in cell metabolic activities induced by ES media treatment. These findings suggest that H2O2 was influencing cell metabolic activity, whereas SPP1 mRNA expression was regulated by other faradic by-products. This study reveals how different electrical stimulation regime alters cellular regenerative responses and the roles of faradic by-products, that might be used as a physical tool to guide and control cell behaviour.
Mouthwashes are used during dental treatments to mitigate the complications caused by poor oral hygiene. However, these solutions also affect the properties of dental appliances, including those used in orthodontics. This point has been investigated in this study focusing on the changes in mechanical properties of polymeric orthodontic ligature ties. Commercial ties from four brands were characterized in terms of their maximum forces and displacement, delivery forces, molecular structures, and microscopic morphology. These properties were compared against the ties, which were rinsed with commercial mouthwashes from three manufacturers. The results showed that mouthwash rinsing significantly reduced the maximum bearable forces of ligature ties by up to 73.1%, whereas the reduction in their maximum displacement was up to 74.5% across all tested brands. Significant changes in microscopic morphology of ligature ties were observed after mouthwash rinsing, but not their molecular structure. Furthermore, mouthwash rinsing also reduced the delivery forces from ligature ties by between 20.9 and 32.9% at their first deformation cycle. It can be concluded from this study that mouthwashes have significant impact on the mechanical properties of polymeric orthodontic ligature ties and could also potentially affect the overall efficacy of orthodontic and other dental treatments.
Biphasic calcium phosphate (BCP)scaffolds comprising hydroxyapatite (HA) and β-tricalcium phosphate (β-TCP) were produced from ultra-pure precursors and processed under an α-TCP–avoiding schedule (1100 °C, 2 h). Quantitative X-ray diffraction (Rietveld/Profex) detected no α-TCP above the ~1 wt% limit of detection and quantified post-sintering phase fractions (wt% HA/β-TCP): 99.26/0.74, 68.51/31.49, and 27.57/72.43. Across compositions, SEM/ImageJ yielded similar mean macropore sizes (≈71–80 µm), while open porosity increased with the HA fraction (27.5 ± 1.8%, 39.1 ± 2.0%, 57.1 ± 2.4%). Compressive strength decreased accordingly (1.07 ± 0.25, 0.24 ± 0.01, 0.05 ± 0.02 MPa), consistent with non-load-bearing use. In ISO-compliant simulated body fluid (28 d), medium pH remained stable (7.33–7.43); mass loss and early Ca2+ depletion increased with β-TCP content, consistent with more extensive surface apatite formation in β-TCP-rich scaffolds. Collectively, these data are consistent with a composition-dependent sequence—β-TCP content → densification/porosity → strength → degradation/apatite kinetics—within the tested conditions and inform parameter-based tuning of BCP scaffolds for non-load-bearing indications (e.g., alveolar ridge preservation, craniofacial void filling).