Preparation and Characterization of CaO/ZnO Core-shell Structured Nanoparticles

Residual bacteria and microleakage in a complicated root canal can often result in reinfection of the periapical tissues. To promote the antibacterial and sealing effects of a root canal filling, core-shell structured CaO/ZnO nanospheres were synthesized using a precipitation method based on a traditional root canal sealer, zinc oxide-eugenol(ZOE). The obtained CaO/ZnO particles had a size of 80-90 nm and a core-shell structure. The film thickness, flow rate, pH, and calcium ion release of the core-shell structured CaO/ZnO nanospheres-eugenol paste were tested. The pH and calcium ion release results showed a slight increase in the prepared nanospheres, with a flow rate of 24.22 mm and a formed film thickness of 30 mu m, which are basically consistent with ISO 6876:2001 standards(regarding dental root canal sealing materials). Cytotoxicity tests showed that the cytocompatibility of the CaO/ZnO nanospheres-eugenol paste was much higher than that of the ZOE or iRoot SP groups(P<0.05). A comparison of the sealing ability and antibacterial activity showed that the core-shell structured CaO/ZnO nanospheres-eugenol paste had significantly better effects than the ZOE and iRoot SP sealers(P<0.05). The core-shell structured CaO/ZnO nanosphere paste displayed excellent sealing and antibacterial properties, and it has promising application potential in endodontics.