Bone Cement 骨水泥

Biphasic Calcium Sulphate 硫酸钙（石膏 ）

The raw material, medical grade calcium sulfate is clinically used in 2 different forms differing in their individual (crystal) water content: (Anusavice 2003)

a) Calcium sulfate hemihydrate (CaSO4 · ½ H2O), also known as "Plaster of Paris"

b) Calcium sulfate dihydrate (CaSO4 · 2 H2O), also known as "Gypsum"

When the CS-hemihydrate is mixed with water, it forms a moldable paste (cement) that sets after a certain time interval. By that, the other CS form, the respective dihydrate is formed: CaSO4 · ½H2O + 1½H2O --> CaSO4 · 2H2O

The complete setting process of CS Hemihydrate needs approx. 20 min and is controlled by the formation and growth of CS dihydrate crystals. In an in vivo scenario, proteins and other biological macromolecules may further retard the setting time to up to 200 min. This is impeding the application procedure as well as the clinical performance of a typical dental application significantly. (Ricci 2000) 

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Xin Wei, DDS, PhD, MS 1st edition 04/11/2020, last revision 04/11/2020