Abstract: Objective: To observe calcific bridge formation, pulp inflammation and the color change of the teeth capped with iRoot BP plus in beagle dogs. Methods: Two 10-month old beagle dogs were selected. A total of 72 teeth in the two dogs were randomly assigned into iRoot BP plus group, MTA group and control group (glass ionomer group). Eight weeks and 12 weeks after direct pulp capping with iRoot BP plus, MTA or glass ionomer, the teeth were extracted. Then histological sections were made and stained with hematoxylin eosi. Calcified bridge formation and dental pulp inflammation were graded, and the change of tooth color was evaluated. Wilcoxon rank sum test was used for statistical analysis. Results: In the iRoot BP Plus or MTA group, most of the specimens formed a complete calcification bridge without pulp inflammation. While in the glass ionomer group, no obvious calcified bridge formation was observed, but the inflammatory reaction, reticular atrophy of the pulp and vacuolar degeneration of the odontoblastic layer appeared. Tooth discoloration was observed in MTA group but not in iRoot BP Plus group. Conclusion: 1) Both iRoot BP Plus and MTA can induce the formation of calcified bridge. 2) iRoot BP Plus and MTA have a good resistance to inflammation. 3) iRoot BP Plus is a better pulp capping agent than MTA.