BACKGROUND: This study aimed to assess the cytotoxicity and proliferation effects of cold ceramic (CC) on stem cells from human exfoliated deciduous teeth(SHEDs) compared to mineral trioxide aggregate(MTA). METHODS: In this in vitro study, the cytotoxicity of fresh and set MTA and CC for SHEDs was assessed after 24 and 72 h using the methyl thiazolyl tetrazolium(MTT) assay. The scratch test was used to evaluate cell migration, while cell morphology and adhesion were assessed by scanning electron microscopy (SEM). Data were analyzed by one-way ANOVA and Tukey test (alpha = 0.05). RESULTS: At 24 h, the cell viability percentage was higher in fresh MTA than fresh CC (P <
0.0001), and in set CC than set MTA (P = 0.0003). At 72 h, cell viability in the presence of both fresh and set MTA was similar to the control group (P = 0.871). Set CC showed significantly higher cell viability (P <
0.0001) while fresh CC decreased cell viability. The scratch was completely healed in the control group. Cell density was lower in the MTA group, and the lowest in the CC group. SHEDs preserved their natural morphology and had optimal cytoplasmic attachment to MTA and CC surfaces after 24 and 48 h. CONCLUSION: Cell viability and migration in CC were comparable to those in MTA and even superior in set form after 72 h. CC caused cell proliferation in addition to migration. Cells had a normal morphology and optimal adhesion in both groups. CC may be suitable for use as an alternative to MTA in pulpotomy of primary teeth. CLINICAL TRIAL NUMBER: Not applicable.