Improving biodegradation behavior of calcium sulfate bone graft tablet by using water vapor treatment.

The biodegradation rate of calcium sulfate hemihydrate (CSH) tablets is extremely rapid. This study adopts a water vapor treatment to modify the surface structure of a CSH tablet. After the treatment, a small amount of calcium sulfate dihydrate (CSD) forms on the surface; the porosity near the surface region decreases, consequently enhancing tablet strength and surface hardness. Because of the decrease in porosity at the surface, the time for complete disintegration increases from 1.2 h to 7.2 h; the time for complete dissolution increases from 7 days to 25 days.