Abstract: Objective To investigate the feasibility of transforming growth factor β1 (TGF-β1) combined with iRoot BP Plus for pulp capping, so as to provide experimental reference for improving the success rate of vital pulp preservation. 
Methods A total of 40 upper and mandibular first molars of 4-week-old male SD rats were obtained, their roots were cut off, and the crown and crown pulp tissues of the first molar were retained. They were randomly divided into four groups for pulp capping: the control group, iRoot BP Plus group, TGF-β1 group, and iRoot BP Plus+TGF-β1 group. The experimental teeth after pulp capping were transplanted into the back pockets of 6-week-old male BALB/C nude mice. At 6 weeks after culture, the nude mice were killed and the samples were stained with HE to evaluate the degree of pulpal inflammation and the formation of reparative dentin or mineralized tissue. The expression of dentin matrix protein 1 (DMP-1) in odontoblasts was detected by immunohistochemistry. 
Results The degree of pulp inflammation and the formation of reparative dentin or mineralized tissue in iRoot BP Plus group, TGF-β1 group, and iRoot BP Plus+TGF-β1 group were better than those in the control group (P＜0.05). The degree of formation of reparative dentin or mineralized tissue in iRoot BP Plus+TGF-β1 group was significantly higher than that in iRoot BP Plus group and TGF-β1 group (P＜0.05). The expression of DMP-1 in odontoblasts of iRoot BP Plus group, TGF-β1 group, and iRoot BP Plus+TGF-β1 group was significantly stronger than that of the control group, and the expression of DMP-1 in odontoblasts of iRoot BP Plus+TGF-β1 group was significantly stronger than that of iRoot BP Plus group and TGF-β1 group (P＜0.05). 
Conclusion iRoot BP Plus and TGF-β1 can promote the formation of reparative dentin or mineralized tissue. iRoot BP Plus combined with TGF-β1 can be used in direct pulp capping, and the ability to form reparative dentin or mineralized tissue was superior to iRoot BP Plus or TGF-β1 alone. 

Key words: dental pulp capping, transforming growth factor β1, iRoot BP Plus