Effect of grain orientation and magnesium doping on β-tricalcium phosphate resorption behavior

Marta Gallo (1) , Bastien Le Gars Santoni (2) , Thierry Douillard (1, 3) , Fei Zhang (1) , Laurent Gremillard (1) , Silvia Dolder (4) , Willy Hofstetter (4) , Sylvain Meille (1) , Marc Bohner (2) , Jérome Chevalier (1) , Solene Tadier (1)

1 MATEIS - Matériaux, ingénierie et science [Villeurbanne]
2 RMS Foundation
3 CLYM - Consortium Lyon Saint-Etienne de Microscopie
4 UNIBE - Universität Bern / University of Bern

The efficiency of calcium phosphate (CaP) bone substitutes can be improved by tuning their resorption rate. The influence of both crystal orientation and ion doping on resorption is here investigated for beta-tricalcium phosphate (β-TCP). Non-doped and Mg-doped (1 and 6 mol%) sintered β-TCP samples were immersed in acidic solution (pH 4.4) to mimic the environmental conditions found underneath active osteoclasts. The surfaces of β-TCP samples were observed after acid-etching and compared to surfaces after osteoclastic resorption assays. β-TCP grains exhibited similar patterns with characteristic intra-crystalline pillars after acid-etching and after cell-mediated resorption. Electron BackScatter Diffraction analyses, coupled with Scanning Electron Microscopy, Inductively Coupled Plasma–Mass Spectrometry and X-Ray Diffraction, demonstrated the influence of both grain orientation and doping on the process and kinetics of resorption. Grains with c-axis nearly perpendicular to the surface were preferentially etched in non-doped β-TCP samples, whereas all grains with simple axis (a, b or c) nearly normal to the surface were etched in 6 mol% Mg-doped samples. In addition, both the dissolution rate and the percentage of etched surface were lower in Mg-doped specimens. Finally, the alignment direction of the intra-crystalline pillars was correlated with the preferential direction for dissolution.

Mots clés: Electron backscatter diffraction (EBSD); Dissolution behavior; Osteoclastic resorption; Crystal orientation; Calcium phosphate

Domaines: Matériaux; Biomatériaux

Marta Gallo, Bastien Le Gars Santoni, Thierry Douillard, Fei Zhang, Laurent Gremillard, et al.. Effect of grain orientation and magnesium doping on β-tricalcium phosphate resorption behavior. Acta Biomaterialia, 2019, 89, pp.391-402. ⟨10.1016/j.actbio.2019.02.045⟩. ⟨hal-02063696⟩