BackgroundAlthough multiple materials have been suggested for pulpotomized primary molars, there is no reliable evidence of the superiority of one particular type. AimTo compare the effectiveness of formocresol (FC), mineral trioxide aggregate (MTA), ferric sulphate, and sodium hypochlorite (NaOCl) as pulp dressing agents in primary molars after 2years. DesignOne hundred primary molars requiring pulp treatment were allocated randomly to the control (FC) and experimental groups (MTA, ferric sulphate, and NaOCl). Clinical and radiographic evaluations were performed at 6, 12, 18, and 24months. Statistical analysis using Fischer's exact test was performed to determine the significant differences between groups. ResultsIn the FC and MTA groups, 100% of the available teeth were clinically successful at all follow-up appointments. In the NaOCl group, one clinical failure was found at 18months, and two clinical failures in the ferric sulphate group were noted at 12 and 24months, but no significant differences were found among the groups (P=0.41). No significant differences in radiographic success were found among all the groups at 24months of follow-up (P=0.303). ConclusionsNo statistically significant differences among the four materials were found at 24months suggesting that NaOCl may be an appropriate substitute for FC.