Three-dimensionally printed polycaprolactone/multicomponent bioactive glass scaffolds for potential application in bone tissue engineering

Over the last years, three-dimensional (3D) printing has been successfully applied to produce suitable substitutes for treating bone defects. In this work, 3D printed composite scaffolds of polycaprolactone (PCL) and strontium (Sr)- and cobalt (Co)-doped multi-component melt-derived bioactive glasses (BGs) were prepared for bone tissue engineering strategies. For this purpose, 30 of as-prepared BG particles (size <38 μm) were incorporated into PCL, and then the obtained composite mix was introduced into a 3D printing machine to fabricate layer-by-layer porous structures with the size of 12 � 12 � 2 mm3. The scaffolds were fully characterized through a series of physico-chemical and biological assays. Adding the BGs to PCL led to an improvement in the compressive strength of the fabricated scaffolds and increased their hydrophilicity. Furthermore, the PCL/BG scaffolds showed apatite-forming ability (i.e., bioactivity behavior) after being immersed in simulated body fluid (SBF). The in vitro cellular examinations revealed the cytocompatibility of the scaffolds and confirmed them as suitable substrates for the adhesion and proliferation of MG-63 osteosarcoma cells. In conclusion, 3D printed composite scaffolds made of PCL and Sr- and Co-doped BGs might be potentially-beneficial bone replacements, and the achieved results motivate further research on these materials. © 2020 Amirhosein Fathi et al., published by De Gruyter 2020

Hardness Evaluation of Porous Hydroxyapatite Coating

International audienceThe extensive use of appropriate coatings to improve wear resistance, friction coefficient, electrical properties, corrosion resistance and biomedical application has stimulated a growing interest in their mechanical properties and especially hardness testing that is routinely used for coating evaluation. In this study Jönsson and Hogmark model is applied for the porous hydroxyapatite produced by plasma spraying on Ti6A14V substrate. Firstly, the effect of indentation load on hardness values of coating and substrate are studied. The modified Jönsson and Hogmark model is used to explain the composite hardness behavior and the effect of coating porosity

Metronidazole-loaded glass ionomer dental cements

The incorporation of antibiotics in glass ionomer cements (GICs) for the treatment of periodontal diseases has been considered as an effective therapeutic strategy. In this research, metronidazole was added to silanized glass fiber-reinforced GICs. The fiber-reinforced cements containing antibiotic were made by adding 6.0 w silanized E-glass fibers and 3.0 w metronidazole to the GIC powder. The GIC reinforced with 6.0 w silanized fibers showed maximum values of 57 MPa, 2.1 GPa, and 1.3 MPa�m0.5 for the flexural strength, flexural modulus, and fracture toughness, respectively. The release of metronidazole showed a two-step release in which about 65 of total amount was released in the first 24 hours. Antibacterial test exhibited no bacteria number (CFU/mL) in the presence of GIC containing metronidazole. In addition, gene expression of Streptococcus mutans was performed by real-time PCR method. Based on PCR results, metronidazole significantly reduced the gtfB and gtfC genes expression, related to adherence and biofilm formation, up to 98 after 7 days in comparison to the control one (P &lt;.001). According to the obtained results, GICs reinforced with silanized fibers containing metronidazole are effective in inhibiting bacteria associated with caries and also acceptable mechanical properties for the development of the next generation of restoration dental materials. © 2020 The American Ceramic Societ

Manufacturing of biodegradable polyurethane scaffolds based on polycaprolactone using a phase separation method: physical properties and in vitro assay

Azadeh Asefnejad1, Mohammad Taghi Khorasani2, Aliasghar Behnamghader3, Babak Farsadzadeh1, Shahin Bonakdar4 1Department of Biomedical Engineering, Science and Research Branch, Islamic Azad University, Tehran, Iran; 2Iran Polymers and Petrochemical Institute, Tehran, Iran; 3Materials and Energy Research Center, Tehran, Iran; 4National Cell Bank of Iran, Pasteur Institute of Iran, Tehran, Iran Background: Biodegradable polyurethanes have found widespread use in soft tissue engineering due to their suitable mechanical properties and biocompatibility. Methods: In this study, polyurethane samples were synthesized from polycaprolactone, hexamethylene diisocyanate, and a copolymer of 1,4-butanediol as a chain extender. Polyurethane scaffolds were fabricated by a combination of liquid&amp;ndash;liquid phase separation and salt leaching techniques. The effect of the NCO:OH ratio on porosity content and pore morphology was investigated. Results: Scanning electron micrographs demonstrated that the scaffolds had a regular distribution of interconnected pores, with pore diameters of 50&amp;ndash;300 &amp;micro;m, and porosities of 64%&amp;ndash;83%. It was observed that, by increasing the NCO:OH ratio, the average pore size, compressive strength, and compressive modulus increased. L929 fibroblast and chondrocytes were cultured on the scaffolds, and all samples exhibited suitable cell attachment and growth, with a high level of biocompatibility. Conclusion: These biodegradable polyurethane scaffolds demonstrate potential for soft tissue engineering applications. Keywords: polyurethane, tissue engineering, biodegradable, fibroblast cell

Properties of Dental Adhesives Incorporated with Boehmite Nano-particles

The incorporation of boehmite nano-particles and its effects on the mechanical properties and bond strength of an experimental dental adhesive were studied.An adhesive solution containing ethanol, Bis-GMA, TMPTMA, HEMA and photo-initiator system (camphorquinone and DMAEMA) was prepared. Silanized boehmite nano-particles were incorporated into the adhesive in different concentrations of 0, 0.2, 0.5, 1, 2, and 5 weight percentages. The suspensions were ultrasonocated to facilitate the nano-particle dispersion. Degree of conversion of the adhesive under visible light irradiation was determined using FT-IR spectroscopy. Depth of cure, diametral tensile strength, flexural strength, and micro-shear bond strength of the adhesives were measured. Scanning electron electron microscopy was utilized to observe the fracture surface topography. The results were compared using one-way ANOVAand Tukey posthoc test at the significance level of 0.05. The results indicated that the diametral tensile strength, flexural strength, and micro-shear bond strength increased at nano-particle contents of 0.2-0.5 wt.% and beyond this range  there was a declining trend (p<0.05) observed in all these properties because of the nano-particle agglomeration.  No significant difference was observed in flexural moduli of the adhesives with different filler contents. The study revealed that the incorporation of boehmite nanoparticles may improve the properties of dental adhesives

Synergistic reinforcement of glass-ionomer dental cements with silanized glass fibres

The purpose of this study is to evaluate the general function and properties of a new class of reinforced glass-ionomer cements (GICs). In this regard, GIC powders based on a molar composition of 4.5SiO2.3Al2O3.1.5P2O5.3CaO.2CaF2 were synthesised via a melt-quenching method. The cement reinforced with silanized fibers (CSFs) were made by adding silanized E-glass fibers to the glass powder, before mixing with FUJI II LC, and then cured. The CSFs achieved maximum values of mechanical properties and showed a lower increase in roughness value compare to the other tested groups. Additionally, the CSFs demonstrated acceptable biocompatibility to fibroblast cells. Reinforcing the GICs with silanized glass fibers could improve the mechanical properties and toughening behavior of the final products, making them a promising biomaterial for dental restorative applications. © 2019, © 2019 Informa UK Limited, trading as Taylor & Francis Group

3D-printed barium strontium titanate-based piezoelectric scaffolds for bone tissue engineering

In order to promote bone healing, new generations of biomaterials are under development. These biomaterials should demonstrate proper biological and mechanical properties preferably similar to the natural bone tissue. In this research, 3D-printed barium strontium titanate (BST)/β-tricalcium phosphate (β-TCP) composite scaffolds have been synthesized as an alternative strategy for bone regeneration to not only induce appropriate bioactive characteristics but also piezoelectric behavior. The physical, chemical and biological performance of the scaffolds have been examined in terms of mechanical, dielectric properties, apatite-forming ability, Alizarin Red Staining (ARS), Alkaline Phosphatase activity (ALP), and cytotoxicity. The samples composed of 60 BST and 40 β-TCP showed the highest compressive strength, bending module, elastic modulus and the Young's modulus. The dielectric constant increased with further addition of the BST phase in the constructs. Scanning Electron Microscope (SEM) and energy dispersive X-ray (EDX) analyses showed that 60 BST/40 β-TCP sample had the highest amount of bone-like apatite formation after 28 days in simulated body fluid (SBF). Moreover, the results of ARS proved that 60 BST/40 β-TCP composite could present higher quantities of mineral deposition. The ALP activity of osteosarcoma cells on 60 BST/40 β-TCP sample showed higher activities compare with the other composites. None of the samples demonstrated any sign of toxicity using MTT test. It can be suggested that BST/β-TCP composite scaffolds can be potentially used as the next generation of bone tissue engineering scaffold materials. © 2019 Elsevier Ltd and Techna Group S.r.l