Formocresol (FC) is the most universally taught and most widely used pulpotomy medicament in the primary teeth. However, concerns have been raised over the use of FC because of its toxicity and potential carcinogenicity. A substitution for FC has been investigated but evidence is lacking to conclude which is the most appropriate technique for pulpotomies in primary teeth. Sodium hypochlorite (NaOCl) has been used in root canal irrigant for more than 80 years, and it is at present the most popular irrigant in root canal treatment. Studies have showed that NaOCl is biological compatible and is a very good antimicrobial solution without being a pulpal irritant. Recent studies using sodium hypochlorite as pulpotomy medicament in primary molars showed promising results. In this project, the investigators propose a randomized clinical trial, which will be performed in Pediatric Dentistry Department of the National Taiwan University Hospital, to compare the treatment outcomes between NaOCl and FC in human primary molars needing pulpotomy treatment. The aim of this sudy is to determining weather NaOCl is a suitable replacement for FC in the pulpotomy of human primary molar teeth. To assess this aim, 200 healthy children from 2.5 to 9 year-old, who have at least one primary first or second molars diagnosed to receive pulpotomy treatment will be recruited in this project. The involved teeth will be randomly assigned to the control group (dilute 20% Formocresol (DFC)) or experimental group (2.5% NaOCl). At 3, 6, 9, 12, 15, 18, 21 and 24 months post-treatment, the randomly assigned teeth will be clinically and radiographically evaluated by blinded independent evaluators to the treatment group. The differences will be statistically analyzed using chi-square test, Fisher exact test, and t-test, using a statistical significance at p<0.05.