Abstract: The online pH value evolutions of a novel Sr-containing calcium phosphate cement (Sr-CPC) pastes together with the extracts of their hardened bodies immersed in the culture medium
were measured and the cytotoxicities of various hardened bodies were evaluated by MTT assay. Results obtained from the XRD and FTIR analyses
show that most of the Sr-CPC has transformed into Sr-containing apatite solid solution after subjected an immersion process in SBF for 24h.
CO₃^2- ion can be detected in the final set product, which is similar to the bone-like apatite. The pH values of various cement pastes basically
vary in the range of 6.5～7.8. All extracts exhibit no or low cytotoxicity with a score of 0 or 1 grade according to the six-grade criterion in GB/T
16175-1996. A slight relevance exists among the cytotoxicity and concentration of extracts and acting time.

Key words: Sr-containing calcium phosphate cement （Sr-CPC）, cytotoxicity, MTT assay, bioma-terials