OBJECTIVE: This study is to compare the dentin bridge thickness achieved using calcium hydroxide and MTA using radiographs. METHODOLOGY: Single blinded randomized controlled trial conducted in the Operative Dentistry department at Fatima Jinnah Dental College and Hospital, Karachi. A total of 100 premolar and molar teeth with class I and II cavities were included in this study. The study participants were assigned into two groups, A and B of 50 participants each. Under local anesthesia, Group A was indirectly pulp capped with Calcium hydroxide (Dycal) and Group B received Mineral Trioxide Aggregate as an indirect pulp capping material. Both groups were then restored with Glass Ionomer Cement. Radiographic follow up was carried out at three and six months to determine mean dentin thickness of reparative dentin bridge. RESULTS: Statistical analysis was performed using SPSS v 23. Independent Sample t-test was applied to evaluate the formation of dentin bridge formation using Ca(OH)2 and MTA at 3 months & 6 months, the outcomes were highly significant (p-value<0.001). Paired sample t-test was applied to evaluate the difference in dentin bridge formation at three months and 6 months, the results were highly significant (p-value <0.001). CONCLUSION: Statistically significant difference was observed in the dentin thickness of reparative dentin bridge amongst the two groups after three months and six months. A greater success rate was noted in the MTA group as compared to the Ca(OH)2 group after 6 months. KEYWORDS: Dentin bridge, Endodontic treatment, Indirect pulp capping, Reparative dentin, randomized controlled trial.