Statement of Problem: Pulpotomoy is considered as one of the most common treatments among primary teeth. Therefore, search for an appropriate and safe material seems necessary. Studies have proved ferosulfate as a therapeutic material in pulpotomy.

Purpose: The goal of the present study was to compare clinical and radiographic changes of pulpotomy using ferosulfate and formocresol in primary molars among 3-8 year old children.

Materials and Methods: In this clinical trial study, fifteen 3-8 years old children, referred to the pedodontics department, faculty of Dentistry, Tehran University of Medical Sciences were selected. All subjects did not show any systemic disease, with at least two clinically and radiographically accepted posterior teeth for pulpotomy technique. Totally, forty- three teeth were studied. For each patient both materials were used. Following treatment, patients were investigated, clinically and radiographically in 3, 6, 9 and 12 month follow-ups. During follow-up periods, teeth with failures were not excluded and investigated. For data analysis, Chi-square and Fisher’s-exact tests were used and treatment success was evaluated, based on clinical as well as radiographic findings.

Results: In all follow-up periods (3, 6, 9 and 12 months after treatment), pulpotomies with formocresol showed more success rate (73.7%) comparing to those with ferosulfate (70.8%), although the difference was not statistically significant (P>0.05). Statistical tests revealed no significant difference between two different treatment techniques regarding pain, external and internal resorption, calcified metamorphosis, abcess, apical root resorption, apical and interradicular radiolucency.

Conclusion: Although ferosulfate, due to its less toxicity, may be considered as a proper substitute for formocresol in primary molars pulpotomies, more studies with longer-term follow up and larger sample size are required to determine its long-term effects.