Effects of mineral trioxide aggregate mixed with hydration accelerators on osteoblastic differentiation. 
Despite good physical and biological properties, mineral trioxide aggregate (MTA) has a long setting time.  A hydration accelerator could decrease the setting time of MTA.  This study assessed the biocompatibility of MTA mixed with hydration accelerators (calcium chloride and low-dose citric acid) and investigated the effect of these materials on osteoblast differentiation.  Cell viability was evaluated by the EZ-Cytox assay kit (Daeil Lab Service, Seoul, Korea).  The gene expressions of osteocalcin and bone sialoprotein were detected by reverse-transcription polymerase chain reaction and real-time polymerase chain reaction.  The mineralization behavior was evaluated with alizarin red staining.  There was no statistically significant difference in cell viability between experimental groups.  The messenger RNA level of osteogenic genes significantly increased in MTA mixed with hydration accelerators compared with the control and MTA mixed with water.  MTA mixed with the hydration accelerators resulted in similar mineralization compared with MTA mixed with water.  Hydration accelerators increase the osteogenic effect and show a similar effect on the mineralization of MTA, which may have clinical applications.