Lithium-doped β-tricalcium phosphate: Effects on physical, mechanical and in vitro osteoblast cell-material interactions.

In this work, we have investigated the effects of lithium (Li) dopant at different concentrations and sintering temperatures on the physical and mechanical properties of β-tricalcium phosphate (β-TCP). Our results showed that Li addition at concentrations of 0.65 and 1.0 wt % inhibits the β-TCP to α-TCP phase transformation. 0.15 wt % Li addition resulted in grain growth and extensive liquid phase was formed at higher concentrations. At 1150°C, compressive strength of β-TCP increased from 138.7 ± 19.9 MPa to 170.9 ± 29.8 MPa with the addition of 0.15 wt % Li. Addition of higher amounts of Li decreased the compressive strength and the lowest compressive strength of 99.8 ± 13.7 MPa was found in samples containing 1.0 wt % Li. After 3 days of culture, osteoblast cells grew to confluence on samples containing 0.65 and 1.0 wt % Li. Cells grew to confluence on all doped samples after 11 days of culture and optical cell density was 4-5 folds higher on 0.15 and 1.0 wt % Li-doped TCP samples. Our results show that both Li content and sintering temperature have significant influence toward physicochemical and mechanical properties of β-TCP which affects the osteoblast cell-materials interaction in Li-doped TCP scaffolds.