Background and Aim: Vital pulpotomy in primary teeth is performed to maintain the vitality of the pulp and tooth until normal exfoliation. Different materials such as zinc oxide- eugenol, calcium hydroxide and formocresol are used in this procedure. The aim of this study was to evaluate the application of formocresol (FC) and mineral trioxide aggregate (MTA) in pulpotomy of primary molars.

Materials and Methods: In this clinical trial, one hundred and twenty six children (aged 5 to 9 years old) with dental caries that were candidate for pulpotomy were selected and randomly divided into two groups. After removing the roof of the pulp chamber, coronal pulp was cut at the orifices and bleeding controlled. In control group, formocresol was applied for 5 minutes. In case group, MTA paste was used as pulpotomy agent. The crowns of both groups were restored with amalgam and the teeth were evaluated clinically and radiographically after 3 and 6 months follow up. Data were analyzed by Fisher test with p<0.05 as the limit of significance.

Results: No sign of clinical failure was observed after 3 and 6 months follow-up. Comparison between the two methods revealed no significant difference in radiographic findings of the teeth and surrounding tissues after 3 months follow-up. However, after 6 months follow-up, internal resorption was observed radiographically in four cases of formocresol group.

Conclusion: Based on the results of this study, pulpotomy with MTA showed more successful results than formocresol radiographically. MTA is recommended as a good substitute for formocresol in pulpotomy of primary molars.