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Calcium phosphate/Bioglass composite coatings on AISI 316L were investigated with regard to their potential role as a beneficial coating for orthopedic implants. These coatings were realized by the galvanic co-deposition of calcium phosphate compounds and Bioglass particles. A different amount of Bioglass 45S5 was used to study its effect on the performance of the composite coatings. The morphology and chemical composition of the coatings were investigated before and after their aging in simulated body fluid. The coatings uniformly covered the AISI 316L substrate and consisted of a brushite and hydroxyapatite mixture. Both phases were detected using X-ray diffraction and Raman spectroscopy. Additionally, both analyses revealed that brushite is the primary phase. The presence of Bioglass was verified through energy-dispersive X-ray spectroscopy, which showed the presence of a silicon peak. During aging in simulated body fluid, the coating was subject to a dynamic equilibrium of dissolution/reprecipitation with total conversion in only the hydroxyapatite phase. Corrosion tests performed in simulated body fluid at different aging times revealed that the coatings made with 1 g/L of Bioglass performed best. These samples have a corrosion potential of −0.068V vs. Ag/AgCl and a corrosion current density of 8.87 × 10−7 A/cm2. These values are better than those measured for bare AISI 316L (−0.187 V vs. Ag/AgCl and 2.52 × 10−6 A/cm2, respectively) and remained superior to pure steel for all 21 days of aging. This behavior indicated the good protection of the coating against corrosion phenomena, which was further confirmed by the very low concentration of Ni ions (0.076 ppm) released in the aging solution after 21 days of immersion. Furthermore, the absence of cytotoxicity, verified through cell viability assays with MC3T3-E1 osteoblastic cells, proves the biocompatibility of the coatings.

Bioglass 45S5 is widely known for its ability to regenerate bone. However, this glass cannot be fully densified by viscous flow due to its very high tendency for crystallization. In this work, we evaluate the sintering and bioactivity of Bioglass 45S5-based compositions in which Na2O is incrementally replaced by K2O. Our sintering tests demonstrated that the densification of Bioglass 45S5 powders can be significantly enhanced due to a decreased crystallization tendency. The composition in which half of the original Na2O content was substituted by K2O exhibits the highest densification rate, evidencing the mixed alkali effect (MAE) in the viscous-flow-driven sintering process. The replacement of Na2O by K2O significantly improved both the densification rate and the in vitro performance. These results are very relevant for this particular glass and also for the design of new bioactive glasses with improved sinterability.

The aim of this work was to obtain porous ceramic parts based on Zirconia stabilized with 5mol.% Yttria (5Y-PSZ), suitable for the infiltration with bioactive glasses, using 3D printed sacrificial polymeric molds. In a first step, honeycomb structured molds were designed with the SolidWorks® software and manufactured by 3D printing using polylactic acid filaments (PLA). These molds were filled with a ceramic mass composed of 5Y-PSZ nanoparticles containing 3wt% polymeric binder and consolidated under pressure of 10MPa and then sintered at 1200 °C-30 min the polymeric molds were consumed. The obtained hexagonal-shaped, porous 5Y-TZP bodies were infiltrated with the bioactive glass 45S5, calcium sodium phosphosilicate, at 1350 °C. The materials were characterized by their relative density, their phase composition by X-ray diffraction analysis, and their microstructure by scanning electron microscopy (SEM-EDS), besides their mechanical properties of hardness and fracture toughness. Pre-sintered 5Y-PSZ substrates exhibit relative density around 75%, and 90% after sintering and Bioglass infiltration. The samples' microstructure is composed of a 5Y-PSZ matrix of sub-micrometric zirconia grains with an average size of 1.0 mm, besides the secondary infiltrated glassy phase homogeneously distributed, with a Ca/P ratio of 1.7, close to the ideal proportion for hydroxyapatite formation. In conclusion, sacrificial molding is an interesting route to obtaining dense Y-PSZ/Bioglass 45S5 composite in a honeycomb format. El objetivo de este trabajo fue obtener piezas cerámicas porosas a base de Zirconia estabilizada con 5mol.% Yttria (5Y-PSZ), aptas para la infiltración con vidrios bioactivos, utilizando moldes poliméricos de sacrificio impresos en 3D. En un primer paso, se diseñaron moldes con estructura de panal con el software SolidWorks® y se fabricaron mediante impresión 3D utilizando filamentos de ácido poliláctico (PLA). Estos moldes se llenaron con una masa cerámica compuesta de nanopartículas de 5Y-PSZ que contenían un 3% en peso de aglutinante polimérico y se consolidaron a una presión de 10 MPa y luego se sinterizaron a 1200ºC-30 min. Se consumieron los moldes poliméricos. Los cuerpos de 5Y-TZP porosos de forma hexagonal obtenidos se infiltraron con el vidrio bioactivo 45S5, fosfosilicato de calcio y sodio, a 1350 °C. Los materiales se caracterizaron por su densidad relativa, su composición de fases por análisis de difracción de rayos X y su microestructura por microscopía electrónica de barrido (SEM-EDS), además de sus propiedades mecánicas de dureza y tenacidad a la fractura. Los sustratos presinterizados de 5Y-PSZ exhiben una densidad relativa de alrededor del 75% y el 90% después de la sinterización y la infiltración de Bioglass. La microestructura de las muestras está compuesta por una matriz 5Y-PSZ de granos de circonio submicrométrico con un tamaño promedio de 1.0 mm, además de la fase vítrea infiltrada secundaria distribuida homogéneamente, con una relación Ca / P de 1.7, cercana a la proporción ideal para formación de hidroxiapatita. En conclusión, el moldeo de sacrificio es una ruta interesante para obtener un compuesto denso Y-PSZ / Bioglass 45S5 en un formato de panal. O objetivo deste trabalho foi a obtenção de peças cerâmicas porosas à base de Zircônia estabilizada com 5mol.% de ítria (5Y-PSZ), adequadas para a infiltração com vidros bioativos, utilizando moldes poliméricos sacrificiais impressos em 3D. Em uma primeira etapa, os moldes estruturados em honeycombs foram projetados com o software SolidWorks® e fabricados por impressão 3D usando filamentos de ácido polilático (PLA). Esses moldes foram preenchidos com uma massa cerâmica composta por nanopartículas 5Y-PSZ contendo 3% em peso de ligante polimérico e consolidados sob pressão de 10MPa e então sinterizados a 1200 ° C-30 min os moldes poliméricos foram consumidos. Os corpos 5Y-TZP porosos de forma hexagonal obtidos foram infiltrados com o vidro bioativo 45S5, fosfosilicato de cálcio e sódio, a 1350 ° C. Os materiais foram caracterizados quanto à densidade relativa, composição de fases por difração de raios X e microestrutura por microscopia eletrônica de varredura (MEV-EDS), além de propriedades mecânicas de dureza e tenacidade à fratura. Substratos pré-sinterizados 5Y-PSZ exibem densidade relativa em torno de 75% e 90% após sinterização e infiltração de Biovidro. A microestrutura das amostras é composta por uma matriz 5Y-PSZ de grãos de zircônia submicrométricos com tamanho médio de 1,0 mm, além do infiltrado secundário fase vítrea distribuída homogeneamente, com relação Ca / P de 1,7, próxima à proporção ideal para formação de hidroxiapatita. Em conclusão, a moldagem sacrificial é uma rota interessante para a obtenção de compósito Y-PSZ / Bioglass 45S5 denso em formato de colmeia.

Lee S., Oh J.Y., Mukaeyama S., et al. Preparation of titanium alloy/bioactive glass composite for biomedical applications via selective laser melting. Materials Transactions 60, 1779 (2019); https://doi.org/10.2320/matertrans.ME201914., Selective laser melting (SLM) is widely used for the additive manufacturing (AM) of metal components, which can produce net shape complex geometries. Novel titanium alloy/bioactive glass composites were successfully fabricated via SLM method for biomedical applications. The fabricated composites contained a Ti₅Si₃ phase, which resulted from the reaction between the titanium alloy and the bioactive glass. The phase can improve the bonding strength between composite and bone. Additionally, the remained amorphous bioactive glass phase could improve bioactivity. The present study opens a new avenue for developing new titanium alloy/bioactive glass composites with optimal bioactivity and bonding strength with the bone.

The efficacy of using a 45S5 Bioglass paste as a remineralizing temporary filling material was compared to fluoride gel (1.23% acidulated-phosphate-fluoride, Gelato Gel, NJ, USA) applied for 24 h and for 4 min and to a temporary filling material (Caviton; GC, Tokyo, Japan).66 extracted human premolars were used. All specimens were sectioned mesio-distally. All specimens were challenged by a demineralization solution (pH4.5) for 4 days. The specimens were divided into 4 groups: (Bioglass), (Fluoride 4-minutes), (Fluoride 24-Hours), and (Temp) (n = 33). 10 specimens were examined by TMR (Transversal Microradiography)to test remineralization capacity of each agent. 8 specimens were assigned to determine the acid resistance of a bonded resin-enamel interface after the various treatment methods. 15 samples were assigned to determine the effect of each agent on the shear bond strength of a single bottle self-etch adhesive system. One way ANOVA was used to compare the obtained results (p 0.05).Specimens treated with 45S5 bioglass showed statistically significant reductions in (delta z) values when compared to the other three groups (p 0.05). Treatment of demineralized enamel by fluoride prior to bonding significantly decreased shear bond strength values, however 45S5 bioglass treatment did not affect the shear bond strength of adhesive system to enamel (p 0.05). The acid-resistance of the interface between resin-enamel was significantly improved when fluoride or bioglass were applied onto the enamel surface prior to demineralization.45S5 bioglass paste has high potential to be used as a remineralizing temporary filling material.

Made available in DSpace on 2021-06-25T10:13:22Z (GMT). No. of bitstreams: 0 Previous issue date: 2021-01-01 Objective: This study evaluates the mechanical, physical, and biological properties of resin-based dental cement (RelyX ARC, 3M ESPE) incorporated with hydroxyapatite and 45S5 bioactive glass. Methods: Bioactive glass (45S5) and hydroxyapatite (HA) were added to cement in different proportions (10 wt% and 20 wt%). Three-point flexural strength, microhardness, surface roughness, film thickness, contact angle, and color were evaluated. Cytotoxicity in human osteoblasts culture (MG63) was evaluated. Statistical analysis was performed using one-way and two-way ANOVA and Tukey tests (α

Bioglass® 45S5 (BG) has an outstanding ability to bond with bones and soft tissues, but its application as a load-bearing scaffold material is restricted due to its inherent brittleness. BG-based composites combine the amazing biological and bioactive characteristics of BG with structural and functional features of other materials. This article reviews the composites of Bioglass® in combination with metals, ceramics and polymers for a wide range of potential applications from bone scaffolds to nerve regeneration. Bioglass® also possesses angiogenic and antibacterial properties in addition to its very high bioactivity; hence, composite materials developed for these applications are also discussed. BG-based composites with polymer matrices have been developed for a wide variety of soft tissue engineering. This review focuses on the research that suggests the suitability of BG-based composites as a scaffold material for hard and soft tissues engineering. Composite production techniques have a direct influence on the bioactivity and mechanical behavior of scaffolds. A detailed discussion of the bioactivity, in vitro and in vivo biocompatibility and biodegradation is presented as a function of materials and its processing techniques. Finally, an outlook for future research is also proposed. © 2017 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 105A: 3197-3223, 2017.

As an inorganic bone graft, the traditional bioglass 45S5 can offer good bioactivity for osteogenesis. Type I collagen (Col-1) can mimic the organic components of natural bone in hybrid materials. Hence, in this study, biomimetic hybrid materials [CBGM (Collagen Bioactive Glass Morsels), CBGM1, CBGS (Collagen Bioactive Glass Strips) and CBGS1] were fabricated using 45S5 granules and high purity Col-1 at a proportion of 8.5:1.5. The surface features of these materials were observed using scanning electron microscopy and element energy dispersive spectroscopic (EDS). The activity of MC3T3-E1 cells, including adhesion, proliferation and gene expression, was significantly improved in the CBGS and CBGS1 groups compared with the 45S5 group. Additionally, X-ray, micro computed tomography, EDS and histomorphology showed that these hybrid materials had significantly enhanced osteogenesis and degradation 6 and 12 weeks after implantation in rabbit femoral condylar defects compared with 45S5. CBGS and CBGS1 were significantly better than CBGM and CBGM1 in terms of osteogenesis and degradability. Consequently, with the improved osteogenesis and the faster degradation rate, the hybrid materials CBGS and CBGS1 are promising bone graft candidates for clinical application. Keywords: Hybrid materials, Bioglass, Collagen I, Osteogenesis, Degradability

Objectives Despite the excellent properties of both pure bioglasses (BG) and BG doped with therapeutic ions (such as Li) in hard tissue applications, there is not enough information about their role in the remineralization and bacterial-growth in oral diseases. The aim of this contribution is to evaluate the effect of both pure BG and BG doped with 5-wt% of Li (BGLi) on both the remineralization of in vitro demineralized human-teeth and the antimicrobial behavior against strains from caries and periodontitis. Methods Bioglass® 45S5 (BG) and BGLi were synthesized by the sol-gel method. The remineralization tests were carried out using in vitro demineralized enamel teeth and evaluated by Electron Microscopy (SEM) and Vickers micro-hardness (HV). The antimicrobial behavior of the particles was evaluated against S. mutans, A. actinomycetemcomitans, and P. gingivalis, representing pathogens from caries and periodontitis. Results Enamel lesion was partially remineralized when both bioglasses (BG and BGLi) were applied on its surface with micro-hardness recoveries around 45 %. They further inhibited the growth of S. mutans and P. gingivalis, at 50 and 200 mg/mL, respectively. BGLi presented a higher toxicity against A. actinomycetemcomitans than BG, with inhibition concentrations of 20 mg/mL and 100 mg/mL, respectively. Conclusions Bioglasses could be used in the treatment of two of the most prevalent oral diseases: caries and periodontitis, promoting the remineralization of the teeth and killing the main pathogens. The presence of Li did not affect the bioactivity of the bioglass and improved the antibacterial effect over A. actinomycetemcomitans strain.

In this study, the best equilibrium among adherence, micro-mechanical properties and coating bioactivity of bioactive glasses (45S5 and 1393) on porous titanium substrates has been explored and their potential uses for bone tissue implants. Porous titanium discs with different porosities (30 and 60 vol.%) and pore size distributions (100–200 and 355–500 µm) were utilized to rationalize their influence on both properties and performance. It was corroborated that porous samples produced a reduction in micro-hardness (~ 2000–4000 N/mm2) and the elastic modulus (~25–50 GPa), obtaining values closer to those of human bones, as well as induced a beneficial role to integrate the coatings. On one hand, bioglass 1393 presented greater capacity for pore infiltration while 45S5 was more bioactive. The results explained the better adherence and microhardness for bioglass 1393 and the significant formation of hydroxyapatite and calcium phosphates of bioglass 45S5, confirmed by 29Si MAS NMR.

Immersion experiments in acellular media are a key step in characterising bioactive glass ion release and apatite precipitation. We show that apatite formation of Bioglass 45S5 and two other glasses is delayed in simulated body fluid (SBF) compared to Tris-HCl buffer, likely owing to high magnesium concentrations in SBF. In addition, FTIR and XRD results suggest apatite formed in SBF to be more disordered owing to higher substitution (e.g. by carbonate). 2.5% Zn for Ca substitution reduced ion release, while 2.5% Mg for Ca substitution showed no such effect, but both substitutions delayed apatite formation in either medium.

Objective To evaluate the effect of load-cycle aging and/or 6 months artificial saliva (AS) storage on bond durability and interfacial ultramorphology of resin-modified glass ionomer cement (RMGIC) applied to dentine air-abraded using Bioglass 45S5 (BAG) with/without polyacrylic acid (PAA) conditioning.Methods RMGIC (Ionolux, VOCO) was applied onto human dentine specimens prepared with silicon-carbide abrasive paper or air-abraded with BAG with or without the use of PAA conditioning. Half of bonded-teeth were submitted to load cycling (150,000 cycles) and half immersed in deionised water for 24 h. They were cut into matchsticks and submitted immediately to microtensile bond strength (μTBS) testing or 6 months in AS immersion and subsequently μTBS tested.Results were analysed statistically by two-way ANOVA and Student–Newman–Keuls test (α = 0.05). Fractographic analysis was performed using FE-SEM, while further RMGIC-bonded specimens were surveyed for interfacial ultramorphology characterisation (dye-assisted nanoleakage) using confocal microscopy. Results RMGIC applied onto dentine air-abraded with BAG regardless PAA showed no significant μTBS reduction after 6 months of AS storage and/or load cycling (p > 0.05). RMGIC–dentine interface showed no sign of degradation/nanoleakage after both aging regimens. Conversely, interfaces created in PAA-conditioned SiC-abraded specimens showed significant reduction in μTBS (p ConclusionsDentine pre-treatment using BAG air-abrasion might be a suitable strategy to enhance the bonding performance and durability of RMGIC applied to dentine. The use of PAA conditioner in smear layer-covered dentine may increase the risk of degradation at the bonding interface.Clinical significanceA combined dentine pre-treatment using bioglass followed by PAA may increase the bond strength and maintain it stable over time. Conversely, the use of PAA conditioning alone may offer no significant contribute to the immediate and prolonged bonding performance of modern RMGICs.

Bioactive glasses, particularly Bioglass® 45S5, have been used to clinically regenerate human bone since the mid-1980׳s, owing to their ability to degrade in physiological solutions, release ions and form an apatite surface layer, which cells adhere to and proliferate on. Although low pH conditions do occur in the human body, e.g. during bacterial infections, in vitro dissolution experiments are usually performed at a physiological pH of 7.3 exclusively. Here, we investigated the dissolution behaviour of 45S5 at low pH (5) and high pH (9) in addition to pH 7.3. The results show that ion release occurs significantly faster at low pH, resulting in significantly faster apatite formation (3 h vs. 6 h at pH 7.3). By contrast, at pH 9 low ion exchange rates were observed, resulting in no significant apatite formation during the time period studied. Results suggest that low pH caused by bacterial infection is unlikely to inhibit apatite formation and, thus, bioactive glass clinical performance.

Evaluating microtensile bond strength (μTBS) and Knoop micro-hardness (KHN) of resin bonded-dentine interfaces created with two methacrylate-based systems either incorporating Bioglass 45S5 (3-ERA/BG) or MTA (3-ERA/WMTA).Solvated resins (50% ethanol/50% co-monomers) were used as primers while their neat counterparts were filled with the two calcium-silicate compounds. Application of neat resin adhesive with no filler served as control (3-ERA). μTBS, KHN analysis and confocal tandem scanning microscopy (TSM) micropermeability were carried out after 24 h and 10 months of storage in phosphate buffer solution (DPBS). Scanning electron microscopy (SEM) was also performed after debonding.High μTBS values were achieved in all groups after 24 h of DPBS storage. On the contrary, solely the specimens created using 3-ERA/BG and 3-ERA/WMTA agents showed no significant reduction in terms of μTBS even after 10 months in DPBS; similarly, they did not restore the average superficial micro-hardness to the level of sound dentine, but maintained unchanged KHN values, and no statistical decrease was found following 10 months of DPBS storage. The only statistically significant changes occurred in the resin-dentine interfaces bonded with 3-ERA that were subjected to a reduction of both μTBS and KHN values with ageing. In terms of micropermeability, adverse results were obtained with 3-ERA while 3-ERA/BG and 3-ERA/WMTA demonstrated a beneficial effect after prolonged DPBS storage.Calcium-silicate filled composite resins performed better than a current etch-and-rinse adhesive and had a therapeutic/protective effect on the micro-mechanical properties of mineral-depleted resin-dentine interfaces.The incorporation of calcium-silicates into dental restorative and bonding agents can create more biomimetic (life-like) restorations. This will not only enable these materials to mimic the physical characteristics of the tooth structure, but will also stabilize and protect the remaining dental hard tissues.

Sauro S, Watson TF, Thompson I, Toledano M, Nucci C, Banerjee A. Influence of air-abrasion executed with polyacrylic acid-Bioglass 45S5 on the bonding performance of a resin-modified glass ionomer cement. Eur J Oral Sci 2012; 120: 168–177. © 2012 Eur J Oral Sci The aim of this study was to test the microtensile bond strength (μTBS), after 6 months of storage in PBS, of a resin-modified glass ionomer cement (RMGIC) bonded to dentine pretreated with Bioglass 45S5 (BAG) using various etching and air-abrasion techniques. The RMGIC (GC Fuji II LC) was applied onto differently treated dentine surfaces followed by light curing for 30s. The specimens were cut into matchsticks with cross-sectional areas of 0.9 mm2. The μTBS of the specimens was measured after 24 h or 6 months of storage in PBS and the results were statistically analysed using two-way anova and the Student–Newman–Keuls test (α = 0.05). Further RMCGIC-bonded dentine specimens were used for interfacial characterization, micropermeability, and nanoleakage analyses by confocal microscopy. The RMGIC–dentine interface layer showed no water absorption after 6 months of storage in PBS except for the interdiffusion layer of the silicon carbide (SiC)-abraded/polyacrylic acid (PAA)-etched bonded dentine. The RMGIC applied onto dentine air-abraded with BAG/H2O only or with BAG/PAA-fluid followed by etching procedures (10% PAA gel) showed no statistically significant reduction in μTBS after 6 months of storage in PBS. The abrasion procedures performed using BAG in combination with PAA might be a suitable strategy to enhance the bonding durability and the healing ability of RMGIC bonded to dentine.

19 Made available in DSpace on 2019-09-11T20:51:31Z (GMT). No. of bitstreams: 0 Previous issue date: 2015 The aim of this study was to evaluate the influence of air-abrasion executed with Bioglass 45S5 on the bonding performance of total and self-etching techniques. Human molars were divided into four groups (n = 5) according to the surface treatment: G1: self-etching without air-abrasion; G2: total-etching without air-abrasion; G3: self-etching with air-abrasion Bioglass 45S5 for 1 min; and G4: total-etching with air-abrasion Bioglass 45S5 for 1 min. The Single Bond Universal (3 M ESPE, St. Paul, Minnesota, USA) was used in both etching techniques. The adhesive was photo-activated by a LED with 800 mW/cm2 irradiance (Ultralume 5, Ultradent Products, South Jordan, UT, USA). Composite resin blocks were made on the dentin using Filtek Z100 (3M ESPE, St. Paul, MN, USA). Then, the samples were cut to obtain sticks attached to a jig in a universal testing machine (EZ Test, Shimadzu, Kyoto, Kansai, Japan) for testing microtensile bond strength (μTBS). The values μTBS of microtensile bond strength were submitted to two-way ANOVA and means were compared by Tukey test (p

Biomaterials are widely used in clinical practice as bone graft substitutes for treating patients with bone defects. A molecular level understanding of the chemical processes at the interface betwe ...

Ion release of Mg- and Zn-substituted Bioglass 45S5 (46.1 SiO2-2.6 P2O5-26.9 CaO-24.3Na2O; mol%; with 0, 25, 50, 75 or 100% of calcium replaced bymagnesium/zinc) was investigated at pH 7.4 (Tris buffer) and pH 4 (acetic acid/sodium acetate buffer) in static and dynamic dissolution experiments. Despite Mg2+ and Zn2+ having the same charge and comparable ionic radii, they influenced the dissolution behaviour in very different ways. In Tris, Mgsubstituted glasses showed similar ion release as 45S5, while Zn-substituted glasses showed negligible ion release. At low pH, however, release behaviour was similar, with all glasses releasing large percentages of ions within a few minutes. Precipitation of crystalline phases also varied, as Mg- and Zn-substitution inhibited apatite formation, and Zn-substitution resulted in formation of zinc phosphate phases at low pH. These results are relevant for glasses used in aluminium-free glass ionomer bone cements, as they show that Zn/Mg-substituted glasses release ions similarly fast as glasses containing no Zn/Mg, suggesting that these ions are no prerequisite for ionomer glasses. Zn-substituted glasses may potentially be used as controlled-release materials, which release antibacterial zinc ions when needed only, i.e. at low pH conditions (e.g. bacterial infection), but not at normal physiological pH conditions.

Critical-sized bone defects have, in many cases, posed challenges to the current gold standard treatments. Bioactive glasses are reported to be able to stimulate more bone regeneration than other bioactive ceramics; however, the difficulty in producing porous scaffolds made of bioactive glasses has limited their extensive use in bone regeneration. On the other hand, calcium phosphate ceramics such as synthetic hydroxyapatite and tricalcium phosphate are widely used in the clinic, but they stimulate less bone regeneration. This paper gives an overview of the recent developments in the field of bioactive nanoparticles, with a focus on nanohydroxyapatite and bioactive glasses for bone repair and regeneration. First, a brief overview of the chemical structure and common methods used to produce synthetic nanohydroxyapatite and bioactive glasses has been presented. The main body of the paper covers the physical and biological properties of these biomaterials, as well as their composites with biodegradable polymers used in bone regeneration. A summary of existing challenges and some recommendations for future directions have been brought in the concluding section of this paper.

Using the microindentation technique, micro-indentations were made on bioglass 45S5 by a spherical diamond indenter for the indentation loads in the range of 50–500 mN at room temperature. Complete anelastic recoveries of the indentation depths and the impression marks were observed for the first time. The recovery rate of the indentation depth decreased with increasing the indentation load. A phenomenological model was proposed to explain the indentation recovery. It found that the recovery rate of the indentation depth was a power-function of the indentation load as supported by the experimental results.

In physiological fluid, a layer of hydroxycarbonate apatite, similar to bone mineral, develops on the surface of Bioglass 45S5. Collagen from the surrounding tissue is adsorbed on this layer that attracts osteoblasts, and favors bone regrowth. Bioglass is therefore an osteoinductive material. Still, due to its brittleness, the glass alone cannot be used to heal large bone defects. To overcome this issue, Bioglass is used to form a composite scaffold with poly(D,L-lactide) (PDLLA), a biodegradable polymer. The goal of this work is to understand Bioglass reactivity throughout scaffold fabrication via a low-temperature route, the solvent casting and particulate leaching technique. Changes in Bioglass (especially its surface) are susceptible to occur both while in contact with the processing fluids and potentially through a reaction with the surrounding polymeric matrix. Here we analyzed the surface changes of three different Bioglass samples: (i) as-received, (ii) treated in solutions that parallel those used in scaffold fabrication, and (iii) extracted from the scaffolds. We showed that extracted, just like treated, Bioglass deviates from the as-received, but to a larger extent. X-ray photoelectron and infrared spectroscopy support the theory that Bioglass surface was modified not just through contact with the solutions in scaffold fabrication, but upon an interaction with the polymeric matrix. The polymer network slows down the Na(+)/H(+) exchange between Bioglass and water used to leach salt particles to create pores within the scaffold. Changes in surface properties affect the bioactivity of Bioglass and thus of the composite scaffolds, and are therefore critical to identify.

The reactivity of bioglasses, which is related to the dissolution of cations and orthosilicate groups in the physiological fluid, strongly depends on the key structural features present at the glass surfaces. On the basis of the composition and the synthetic routes employed to make the glass, surfaces with very different characteristics and thus presenting different mechanisms of dissolution can be observed. In this paper, the surface structures of two very different bioglass compositions, namely 45S5 (46.1 SiO2, 24.4 Na2O, 26.9 CaO, and 2.6 P2O5 mol %) and 77S (80.0 SiO2, 16.0 CaO, and 4.0 P2O5 mol %), have been investigated by means of periodic DFT calculations based on a PBE functional and localized Gaussian basis set as encoded in the CRYSTAL code. Our calculations show that the two glass surfaces differ by the relative amount of key structural sites such as NBOs, exposed ions, orthosilicate units, and small rings. We have demonstrated how the number of these sites affects the surface stability and reactivity (bioactivity).

The present study examined the elemental distribution with depth from the surface of Bioglass 45S5 immersed in simulated body fluid (SBF) in the presence or absence of proteins derived from foetal calf serum for 960 h using energy dispersive spectroscopy (EDS). The changes in elemental composition of the surface of Bioglass were also analysed with EDS for different immersion times (10 min to 960 h) before and after immersion in SBF with or without proteins. The presence of proteins consistently altered the elemental composition of Bioglass with depth from the surface, although the development of a silica rich layer was similar in both the presence or absence of proteins. In the presence of proteins the accumulation of calcium phosphate at the surface of Bioglass was slower, formed a narrower layer and had lower concentrations of calcium and phosphate than the calcium phosphate rich layer that developed in SBF alone.

The aim of this study was to test the microtensile bond strength (μTBS), after 6 months of storage in PBS, of a resin-modified glass ionomer cement (RMGIC) bonded to dentine pretreated with Bioglass 45S5 (BAG) using various etching and air-abrasion techniques. The RMGIC (GC Fuji II LC) was applied onto differently treated dentine surfaces followed by light curing for 30 s. The specimens were cut into matchsticks with cross-sectional areas of 0.9 mm(2). The μTBS of the specimens was measured after 24 h or 6 months of storage in PBS and the results were statistically analysed using two-way anova and the Student-Newman-Keuls test (α = 0.05). Further RMCGIC-bonded dentine specimens were used for interfacial characterization, micropermeability, and nanoleakage analyses by confocal microscopy. The RMGIC-dentine interface layer showed no water absorption after 6 months of storage in PBS except for the interdiffusion layer of the silicon carbide (SiC)-abraded/polyacrylic acid (PAA)-etched bonded dentine. The RMGIC applied onto dentine air-abraded with BAG/H(2)O only or with BAG/PAA-fluid followed by etching procedures (10% PAA gel) showed no statistically significant reduction in μTBS after 6 months of storage in PBS. The abrasion procedures performed using BAG in combination with PAA might be a suitable strategy to enhance the bonding durability and the healing ability of RMGIC bonded to dentine.

A series of Ga-containing phospho-silicate glasses based on Bioglass 45S5, having molar formula 46.2SiO2·24.3Na2O·26.9CaO·2.6P2O5·xGa2O3 (x=1.0, 1.6, 3.5), were prepared by fusion method. The reference Bioglass 45S5 without gallium was also prepared. The synthesized glasses were immersed in simulated body fluid (SBF) for 30 days in order to observe ion release and hydroxyapatite (HA) formation. All Ga-containing glasses maintain the ability of HA formation as indicated by main X-ray diffractometric peaks and/or electronic scanning microscopy results. HA layer was formed after 1 day of SBF soaking in 45S5 glass containing up to 1.6% Ga2O3 content. Moreover, gallium released by the glasses was found to be partially precipitated on the glass surface as gallium phosphate. Further increase in gallium content reduced the ion release in SBF. The maximum of Ga(3+) concentration measured in solution is ~6 ppm determined for 3.5% Ga2O3 content. This amount is about half of the toxic level (14 ppm) of gallium and the glasses release gallium till 30 days of immersion in SBF. Considering the above results, the studied materials can be proposed as bioactive glasses with additional antimicrobial effect of gallium having no toxic outcome.

The purpose of this study was to investigate the effects of Bioglass 45S5 and Biosilicate, on bone defects inflicted on the tibia of rats. Fifty male Wistar rats were used in this study, and divided into five groups, including a control group, to test Biosilicate and Bioglass materials of two different particle sizes (180-212 microm or 300-355 microm). All animals were sacrificed 15 days after surgery. No significant differences (P > 0.05) were found when values for Maximal load, Energy Absorption and Structural Stiffness were compared among the groups. Histopathological evaluation revealed osteogenic activity in the bone defect for the control group. Nevertheless, it seems that the amount of fully formed bone was higher in specimens treated with Biosilicate (granulometry 300-355 microm) when compared to the control group. The same picture occurred regarding Biosilicate with granulometry 180-212 microm. Morphometric findings for bone area results (%) showed no statistically significant differences (P > 0.05) among the groups. Taken together, such findings suggest that, Biosilicate exerts more osteogenic activity when compared to Bioglass under subjective histopathological analysis.

The IR spectrum of the Bioglass 45S5 (of composition 46.1 SiO2, 24.4 Na2O, 26.9 CaO, and 2.6 P2O5 mol %) has been simulated by means of periodic ab initio B3LYP calculations. The initial glass structure unit cell envisaging 78 atoms was generated through a melt quench process by means of classical molecular dynamics simulations. The molecular mechanics optimized unit cell has then been fully reoptimized (both unit-cell parameters and internal coordinates) at B3LYP level in a periodic approach using Gaussian basis sets of double-ζ quality by means of the CRYSTAL06 code. Although long-range structural properties cannot be modeled by using this ab initio approach because of the intrinsic amorphous nature of the glass, the quantum mechanical simulation proved to be extremely effective in predicting and analyzing the vibrational features of this biomaterial. The effect of modifiers Na and Ca cations on the network dynamics has been assessed by comparing the 45S5 vibrational spectrum with that of amorphous v-Si...