Fluidity and high thermal conductivity of gutta-percha composites increased by two-dimensional boron nitride and rod-like ZnO for root canal therapy

Boron nitride is a two-dimensional (2D) plate-like material with excellent thermal conductivity and lubricity. In this study, BN is introduced into Gutta-Percha (GP)/zinc oxide (ZnO) composites, and after orientation treatment, the GP@ZnO/BN composites with high TC and excellent fluidity are prepared. Moreover, the “skateboard effect” between BN plates and rod-like ZnO particles is proposed in this paper and confirmed, affording oriented GP@ZnO/5-BN lower shear viscosity (371.88 Pa·s) and higher thermal conductivity (1.65 Wm −1 K −1 ) than those of GP/ZnO composites. Specifically, in vitro experiments, with the assistance of the “skateboard effect,” the lateral root canals filling depth (0.980 mm) of oriented GP@ZnO/5-BN composites exhibit 69.55, 49.62, and 49.16% deeper than that of commercial Bio Gutta-Percha points, MTWO Gutta-Percha points (VP), and PROTAPER universal Gutta-Percha points, respectively. Furthermore, the cytotoxicity level of the GP@ZnO/5-BN composites manifest 0–1 and the X-ray image of the GP@ZnO/5-BN composites depict similar radiopacity effect with DPP point, indicating that the oriented GP@ZnO/5-BN composites are safe and qualified as the commercial GP point materials. Graphical abstract