On November 24, 2024, Nature Communications published an article, titled “Hierarchically mimicking outer tooth enamel for restorative mechanical compatibility,” reporting huge progresses in the production and mechanical performance of the hierarchical enamel analog achieved by Prof. Guo Lin and Academician Jiang Lei’s team as well as their collaborators.

Lu Junfeng, a PhD candidate from the School of Chemistry of Beihang University, is the first author of the article. Co-first authors include the postdoctoral researcher Deng Jingjing and Prof. Wei Yan from Peking University School and Hospital of Stomatology, and the postdoctoral researcher Yang Xiuyi from the School of Chemistry of Beihang University. Co-corresponding authors include Prof. Guo Lin, Academician Jiang Lei, and Prof. Zhao Hewei from the School of Chemistry of Beihang University and Prof. Deng Xuliang from Peking University School and Hospital of Stomatology. Beihang University is listed as the primary completing institution.

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.

This study successfully synthesized a hierarchical enamel analog (HEA) with the same hierarchical structure and similar inorganic components as that of outer tooth enamel using a sequential three-step strategy. As a result, the HEA possesses comparable outer enamel stiffness (84.3 GPa), hardness (3.9 GPa), and viscoelasticity (4.2 GPa) for restorative mechanical comparability, as well as outstanding toughness (19.8 MPa m1/2) for long-term durability, showing great potential for enamel restoration. The outer enamel-like hierarchical structure and hierarchical fracture resistance contribute to the excellent mechanical performance of HEAs. This hierarchical design can facilitate a new path for synthesizing mechanically comparable enamel-restorative materials and mechanical property optimization.

Fig. 1: Structure and mechanical properties of HEA

Fig. 2: Mechanical properties of enamel, hierarchical enamel analog (HEA), and enamel analog (EA)

Fig. 3: Comparison of the durability between enamel, hierarchical enamel analog (HEA), and enamel analog (EA)

The specific toughness of HEAs (15.2 MPa/m1/2/(g/cm3)) is the highest among engineering ceramics, polymers and metals, while the value of specific strength for HEAs (101 MPa/(g/cm3)) is relatively high, further substantiating the superiority of the hierarchical design of HEAs and endowing HEA with potential applications for building materials, vehicles, aerospace, etc.

Fig. 4: Fracture resistance properties of HEA

The work was supported by the National Key R&D Program of China, the National Natural Science Foundation of China, and the Beijing Municipal Science & Technology Commission.

Original article link: https://doi.org/10.1038/s41467-024-54576-5

Written by: Kang Jianxin

Reviewed by: Liu Kesong

Edited by: Jia Aiping

Translated by: Hu Xueyang