Additive manufacturing of bone replacement implants from crystallising bioactive glasses

• Applicants: Professor Dr.-Ing. Aldo Boccaccini; Professorin Dr. Andrea de Camargo, since 12/2023
• Subject Area: Biomaterials ; Synthesis and Properties of Functional Materials
• Term: from 2020 to 2024
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 435860394

• Final Report Year: 2024

Final Report Abstract

The project aimed to acquire fundamental knowledge on the influence of glass powder preparation and processing, as well as 3D printing process parameters and sintering conditions on the manufacture and bioactivity of artificial bone replacement materials made of bioactive glass. During the project, the key influencing factors such as the influence of milling conditions, particle size fraction, binder saturation, powder bed temperature and layer thickness on the manufacturing of additively printed compacts and complex structures, as well as their sintering and crystallization behavior, were investigated in a targeted manner. The three investigated bioactive glasses 13-93, the fluoride-containing F3 and its 1-molar copper-doped variation F3-Cu were also fundamentally characterized regarding their thermal behavior and the kinetics of crystallization. In comparison, the glass 13-93 showed a lower crystallization tendency, which enabled the production of glassy bodies for all particle size fractions. However, the particle size limits the achievable complexity. In the F3 and F3-Cu glasses, the grain size-dependent crystallization reduced or limited sintering and generated partially crystalline surface bodies. However, this also shows a potential to stabilize complex fine structures directly after densification without causing significant negative effects on the proven bioactivity with regard to solubility and cell proliferation. All tested glasses formed a superficial hydroxyapatite layer after seven days of exposure to simulated body fluid. Indirect studies with bone-forming cells showed cell adhesion with characteristic morphology and proliferation expected for biocompatible materials after three days of incubation. After an undesired initial toxic effect on the number of cells, the glass F3-Cu showed significantly increased proliferation. In addition, it was generally shown that a lower surface roughness has a positive effect on cell proliferation and that the direction of growth is oriented towards macroscopic defects. The project has succeeded in determining the influence of the process parameters for the successful production of additively manufactured complex bodies for bone replacement implants made of crystallizing bioactive glasses, expanding the range of particle sizes that can be used and investigating limitations.

Publications

• 3D Printed Bioactive Glass Scaffolds: Effect of Structural Design and Composition on in vitro Cytocompatibility. BioCeramics 32 (2022) Venedig, Italien; (Vortrag)
  Q. Nawaz, C. Blaeß, R. Müller & A. R. Boccaccini
  
• 3D printing of crystallizing bioactive glasses. 26th International congress on glass (2022) Berlin, Deutschland; (Vortrag)
  C. Blaeß, J. Wilbig, Q. Nawaz, A. R. Boccaccini & R. Müller
  
• Biological characterization of novel bioactive glasses suitable for 3D printing. 26th International congress on glass (2022) Berlin, Deutschland; (Vortrag)
  Q. Nawaz, C. Blaeß, R. Müller & A. R. Boccaccini
  
• Sintering and foaming of bioactive glasses. Journal of the American Ceramic Society, 105(11), 6616-6626.
  Blaeß, Carsten & Müller, Ralf
  
• Processing and cytocompatibility of Cu-doped and undoped fluoride-containing bioactive glasses. Open Ceramics, 18, 100586.
  Nawaz, Q.; Blaeß, C.; Müller, R. & Boccaccini, A.R.
  
• Sintering and crystallization kinetics of bioactive glass 13–93. Journal of Non-Crystalline Solids, 627, 122790.
  Blaeß, Carsten; Müller, Ralf & Boccaccini, A.R.