Natural tooth enamel and its analogs

Tooth enamel, the outer shell of the tooth measuring several millimeters, is the hardest tissue of human body to masticate food and protect the inner dentin. The all-around mechanical properties and multiscale-oriented aligned nanoprism structure of tooth enamel have attracted wide interests from both clinical applications and materials scientists. Here, we focus on analyzing the structure-property relationship of tooth enamel and summarize the tooth-enamel analogs based on detailed mimicking of their hierarchy. The underlying principles relating to the formation process and hierarchical structure to excellent mechanical properties in enamel are first introduced to explain the design concept of enamel analogs. Based on this, the synthesis of enamel analogs by biomimetic remineralization and physical-chemical processes-assisted assembly are discussed. Furthermore, the promising applications of these enamel analogs are exhibited. Finally, a brief summary of present enamel analogs and perspective for the next generation of enamel analogs are proposed.