Objective: To investigate the responses of dog pulp tissue to the new nano-hydroxyapatite/polyamide 66 biological composites (nHA-PA66) used as direct pulp capping agent.
Methods: Dogs were used in establishing the experimental model. The reparative dentin bridge formation and the histopathological changes at the pulp-exposed site were observed at 7, 30 and 60 days postoperatively. Calcium hydroxide (Dycal) was used as positive control.
Results: After capping with nHA-PA66, some dog teeth were found to have formation of reparative dentin bridge and slight inflammatory response during the pulp healing procedure when compared with the effect of using calcium hydroxide.
Conclusion: The results indicate that nHA-PA66 has good tissue biocompatibility, but its function of inducing reparative dentin bridge formation is not good enough as compared with that of calcium hydroxide. It has the potential to be used as a direct pulp capping agent, but further researches are needed.