Objective: The present study determined whether primary molar pulpotomies showed equal in vitro and clinical success when restored with sandwich restoration with a bulk-fill flowable composite (BFRBC) liner versus a stainless steel crown (SSC) restoration. Study design: Sixty extracted human primary second molars with proximo-occlusal cavities were selected for in vitro test. The specimens were randomly divided into three groups (n = 20) and restored with sandwich restoration with a BFRBC liner, composite (RBC) restoration and SSC. In addition, sixty teeth were selected from 20 children and each child had at least three primary molars (first and/or second primary molar) requiring pulpotomy. The patients were recalled for clinical and radiographic evaluation at approximately 6- and 12-month intervals. Results: The SSC restoration had significantly higher microleakage than the others. Although there was a significant difference between the RBC and the SSC (P = 0.02), the differences between the BFRBC and the RBC, as well as between the BFRBC and the SSC, were not statistically significant at the 12-month radiographic evaluation (P = 0.33 and P = 0.11, respectively). Conclusion: In laboratory conditions, sandwich restoration with BFRBC liner showed a superior seal margins of pulpotomized primary molars. Based clinical and radiographical evaluation, teeth treated with formocresol pulpotomy and restored with sandwich restoration with BFRBC liner were as successful as those restored with a SSC.