Enamel Repair with Amorphous Ceramics

Developing high-performance materials in physiological conditions to clinically repair stiff tissue for long lifespan remains a great challenge. Here, an enamel repair strategy is reported by efficiently growing a biocompatible ZrO2 ceramic layer on defective enamel through controllable hydrolysis of Zr4+ in oral-tolerable conditions. Detailed analysis of the grown layer indicates that the grown ZrO2 ceramic is amorphous without grain boundary and dislocation, which endows the repaired enamel with natural enamel comparable mechanical performance (modulus ≈82.5 GPa and hardness ≈5.2 GPa). Besides, the strong chemical connection between unsaturated coordinated Zr4+ in amorphous structure and PO43- greatly strengthen the crystalline-amorphous interface of the repaired enamel to endure the long-time mastication damage. Moreover, these ZrO2 ceramics provide hydrophilic, electronegative, and smooth surfaces to resist the adhesion and proliferation of cariogenic bacteria. The hybrid amorphous-crystalline interface design with advantages in biomechanical compatibility would promote the evolution of a variety of cutting-edge functional materials for medical and engineering application.