In Vitro Assessment of Bioactive Glass Coatings on Alumina/Zirconia Composite Implants for Potential Use in Prosthetic Applications

Abstract

Achieving the stable osteointegration of prosthetic implants is one of the great challenges of modern orthopedic surgery. The fixation of ceramic acetabular cups of hip joint prostheses is usually achieved using a metal shell provided with screws or pegs that penetrate into the host pelvic bone. The deposition of bioactive coatings on the implant surface to be put in contact with bone could be a valuable strategy to promote a more “physiological” osteointegration. In this work, bioactive glass porous coatings were manufactured on the top of alumina/zirconia composite implants by two different methods, i.e., sponge replication and laser cladding. The coated samples underwent immersion studies in Kokubo’s simulated body fluid (SBF) to assess in vitro bioactivity and were found to exhibit an excellent hydroxyapatite-forming ability, which is key to allow bonding to bone. Biological tests using mesenchymal stem and osteoblast-like cells revealed the good biocompatibility of both types of materials. Furthermore, a higher level of mineralization was induced by the sponge-replicated coatings at 10 days. Overall, these results are highly promising and encourage further research on these materials.

Modelling the relationship between tensile strength and porosity in bioceramic scaffolds

“…The surface roughness of the scaffold walls can be attributable to the presence of crystalline phases (Figure 1) that develop during the sintering stage. 30 Figure 2B also shows that the scaffold macropores have a diameter well above 100 µm and are interconnected, which are key properties to allow body fluids to flow into the scaffold and cells to migrate inside it. 26 Early studies carried out in the 1990s have provided a first evidence that osteoblastic cells attach and proliferate preferably on surfaces that exhibit a diffused micrometric roughness.…”

“…Preliminary in vitro biological tests on the glass-ceramic material investigated in this work revealed a good biocompatibility with mesenchymal stem cells and osteoblast-like cells (osteosarcoma Saos-2 line). 30 Figure 2B also shows that the scaffold macropores have a diameter well above 100 µm and are interconnected, which are key properties to allow body fluids to flow into the scaffold and cells to migrate inside it. 3 The total porosity of the scaffolds varies in the range of 0.40-0.79 depending on the solid load used in the slurry during the fabrication process (Table 1): in general, higher the solid load, lower the porosity and higher the tensile strength.…”

Laser Surface Texturing of Alumina/Zirconia Composite Ceramics for Potential Use in Hip Joint Prosthesis

“…The sintering curve contained a 2 h stop at 160 °C that yielded the final mechanical properties, i.e., ceramic cup samples to be utilized in the subsequent steps, as shown in Figure 1d. The details of the process for obtaining the discs required for testing are fully described in [21]. Comparing with the process for the cups, all steps (hydrostatic pressing, machining, and heat treatments) were analogous, taking into consideration that the dimensions of the initial cylinders were much smaller in the discs' case.…”

“…Comparing with the process for the cups, all steps (hydrostatic pressing, machining, and heat treatments) were analogous, taking into consideration that the dimensions of the initial cylinders were much smaller in the discs' case. Also, the machining operations for the discs were simpler, as they could be undertaken simply via turning operations in a Multitask Centre [21]. The subjection methods utilized for fixing the green cylinders to be machined in the milling center were those described in [29].…”

“…Recently, porous bioactive glass coatings have also been manufactured by sponge replication [17][18][19] or laser cladding [20,21] on the outer surface of the alumina/zirconia monolithic cup in order to take advantage from both the trabecular bone-like morphology of the coating and the inherent bioactivity of the glass used.…”