OBJECTIVEThis study aims to investigate the effects of mineral trioxide aggregate (MTA) and calcium hydroxide on proliferation and differentiation of human pulp cells from primary and permanent teeth.

METHODSCell proliferation was detected by methyl thiazolyl tetrazolium (MTT) assay. The mRNA expression levels of dentinogenesis-related factors, including alkaline phosphatase (ALP) and dentin sialophosphoprotein (DSPP), and odontoclastogenesis-related factors, such as osteo- protegerin (OPG) and receptor activator of NF-κB ligand (RANKL), were determined by real time polymerase chain reac- tion (PCR).

RESULTSPrimary and permanent pulp cells treated with calcium hydroxide exhibited significantly lower proli- feration rates than the control cells (P<0.01). By contrast, the MTA-treated group showed significantly higher proliferation rates than the control group (P<0.01). Real time PCR results showed that calcium hydroxide-treated primary pulp cells exhi- bited significantly decreased ALP, DSPP, and OPG expression compared with the control group (P<0.01). Conversely, the MTA-treated group displayed significantly increased ALP, DSPP, and OPG expression (P<0.01). Calcium hydroxide-treated primary pulp cells also exhibited significantly upregulated RANKL expression (P < 0.01); by contrast, MTA-treated cells did not show any change in RANKL expression (P>0.05). Likewise, MTA-treated permanent pulp cells showed significantly upregulated ALP and DSPP expression (P < 0.01). However, the calcium hydroxide-treated group remained almost the same as the control group (P > 0.05). Neither MTA nor calcium hydroxide affected OPG and RANKL expression in per- manent pulp cells (P > 0.05).

CONCLUSIONMTA is more suitable as a pulp-capping agent, particularly in primary teeth, than calcium hydroxide.