Background and Aims: Formocresol is one of the most common pulpotomy medicaments for primary teeth. Because of its systemic and local side effects, it may be essential to use another material instead of formocresol. The aim of this study was to evaluate the histopothalogy of pulp after pulpotomy teeth with sodium hypochlorite and formocresol.

Materials and Methods: In this randomized clinical trial, 22 canine teeth that must be extracted because of orthodontic treatment were selected. The teeth were randomly divided into 2 groups (n=11) and pulpotomized with formocresol or sodium hypochlorite. These teeth were extracted after 2 months and pulpal response was evaluated according to the degree of inflammation and extent of pulpal involvement. Dentinal bridge formation was also evaluated. The data were analyzed by Mann-Whitney test.

Results: In formocresol group, mild inflammation was seen in 4 and moderate inflammation in 3 and severe inflammation in 4 cases. In sodium hypochlorite group mild inflammation was seen in 6 cases and moderate inflammation in 4 cases and severe inflammation in 1 case. Mann-Whitney test revealed that this difference was not statistically significant (P>0.05). In formocresol group, necrosis was seen in 5 cases, but abscess and internal resorption were not seen in any cases. In sodium hypochlorite group, internal resorption was seen in 3 cases; but necrosis and abscess were not seen in any cases.  Mann-Whitney test showed that the difference between two groups was significant in terms of necrosis (P=0.02). In sodium hypochlorite group, dentinal bridge was formed in 3 cases; however, no dentinal bridge formation was seen in formocresol group. Mann-Whitney test showed that this difference was not significant statistically (P>0.05).

Conclusion: Based on the results of this study, sodium hypochlorite can be used as a pulpotomy agent in primary teeth.