Hierarchically mimicking outer tooth enamel for restorative mechanical compatibility
Junfeng Lu, Jingjing Deng, Yan Wei, Xiuyi Yang, Hewei Zhao, Qihan Zhao, Shaojia Liu, Fengshi Li, Yangbei Li, Xuliang Deng, Lei Jiang, Lin Guo
Abstract
Tooth enamel, and especially the outer tooth enamel, is a load-resistant shell that benefits mastication but is easily damaged, driving the need for enamel-restorative materials with comparable properties to restore the mastication function and protect the teeth. Synthesizing an enamel analog that mimics the components and hierarchical structure of natural tooth enamel is a promising way to achieve these comparable mechanical properties, but it is still challenging to realize. Herein, we fabricate a hierarchical enamel analog with comparable stiffness, hardness, and viscoelasticity as natural enamel by incorporating three hierarchies of outer tooth enamel based on hierarchical assembly of enamel-like hydroxyapatite hybrid nanowires with polyvinyl alcohol as a matrix. This enamel analog possesses enamel-similar inorganic components and a nanowire-microbundle-macroarray hierarchical structure. It exhibits toughness of 19.80 MPa m1/2, which is 3.4 times higher than natural tooth enamel, giving it long-term fatigue durability. This hierarchical design is promising for scalable production of enamel-restorative materials and for optimizing the mechanical performance of engineering composites. Mechanical compatibility is highly desirable for enamel restorative materials. Here, the authors engineer a hierarchical enamel analog with comparable mechanical properties as outer enamel, showing great potential for enamel restoration.