Amorphous bioactive glasses such as 45S5 have been successfully used in bone‐filling therapy in non‐load bearing biomedical applications for decades. In this study, we challenge the predilection to amorphous over crystalline ceramics by investigating the effect of synthesis route on surface texture, in vitro dissolution, and mineral formation on powders produced by sol–gel and glass melt‐casting methods. Many reports have indicated bulk crystalline bioactive glass‐ceramics to be less bioactive than their amorphous counterparts as measured by the onset time for mineral formation. Bioactive glass 45S5 was synthesized using the sol–gel method followed by heat treatment to produce a semi‐crystalline structure and was compared against commercially available amorphous melt‐cast 45S5 powder. Gel‐derived samples were stabilized at 700°C making more than 80% of the structure crystalline. Dissolution of 45S5 glass‐ceramic in powder form(particle diameter 12 μm) was studied by in vitro immersion in simulated body fluid solution for various periods of time. The immersed powders were then analyzed through X‐ray diffraction (XRD), Scanning electron microscopy (SEM), energy dispersive X‐ray analysis (EDS), Differential scanning calorimetry (DSC), and thermogravimetric analysis (DSC/TGA), and Fourier transform infrared spectroscopy (FTIR) to determine the onset time for surface mineralization, and were compared with the melt‐cast powder as a control. The rates of dissolution and onset time for mineral formation were similar for the gel‐derived powder as compared with the melt‐cast control; it is proposed that the higher surface area of the sol–gel powder overcame the penalty usually associated with lower dissolution rates of crystalline materials, implicating surface texture as a much more important determinant of dissolution and mineralization behavior than mere crystallinity.

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Despite its medical applications, the mechanisms responsible for the osseointegration of bioactive glass (45S5) have yet to be fully understood. Evidence suggests that the strongest predictor for osseointegration of bioactive glasses, and ceramics, with bone tissue as the formation of an apatitic calcium phosphate layer atop the implanted material, with osteoblasts being the main mediator for new bone formation. Most have tried to understand the formation of this apatitic calcium phosphate layer, and other bioresponses between the host and bioactive glass 45S5 using Simulated Body Fluid; a solution containing ion concentrations similar to that found in human plasma without the presence of proteins. However, it is likely that cell attachment is probably largely mediated via the adsorbed protein layer. Plasma protein adsorption at the tissue bioactive glass interface has been largely overlooked. Herein, we compare crystalline and amorphous bioactive glass 45S5, in both melt-derived as well as sol-gel forms. Thus, allowing for a detailed understanding of both the role of crystallinity and powder morphology on surface ions, and plasma protein adsorption. It was found that sol-gel 45S5 powders, regardless of crystallinity, adsorbed 3-5 times as much protein as the crystalline melt-derived counterpart, as well as a greater variety of plasma proteins. The devitrification of melt-cast 45S5 resulted in only small differences in the amount and variety of the adsorbed proteome. Surface properties, and not material crystallinity, play a role in directing protein adsorption phenomena for bioactive glasses given the differences found between crystalline melt-cast 45S5 and sol-gel derived 45S5.