Abstract: Objective: To investigate the ability for pulp to form hard tissue when PRF membrane combined with MTA was used as a new compound pulp capping agent for direct pulp capping. Methods: 32 New Zealand rabbits were randomly divided into 4 groups with 8 experimental rabbits in each group and central mandibular incisors of each rabbit were used as experimental teeth and received the same treatment. According to the different capping materials, they were divided into three experimental groups (PRF+MTA group, MTA group, PRF group) and blank control group; establishment the dental pulp exposure model and direct pulp capping. The experimental teeth were filmed with CBCT immediately before and after surgery, on the 7th and 28th day, and Mimics19.0 software was used to reconstruct the experimental teeth and calculate the volume of dentine bridge formed at the perforating pulp hole. Results: On 7th day after surgery, the dentine bridge volumes in three experimental groups were all larger than those in the blank control group (P<0.05), but there was no significant difference among three experimental groups (P>0.05). On 28th day after surgery, the dentine bridge volume of PRF+MTA group was larger than that of PRF group and blank control group (P<0.05), but there was no statistically significant difference between the PRF+MTA group and MTA group (P>0.05). Conclusion: From the perspective of imaging, the level of PRF combined with MTA in promoting the formation of restorative dentin was not different from that of MTA, both of which were at a high level. However, the nature of the generated restorative dentin and the state of dental pulp required more study by histological observation.

Key words: platelet-rich fibrin, MTA, direct pulp capping, Mimics