Scientists Develop Self-Healing Dental Enamel By Mimicking Epidermal Layers Interview with:
“chipped tooth” by bagaball is licensed under CC BY 2.0 Dr. Ming Yang

Key Laboratory of Microsystems and Microstructures Manufacturing,
Harbin Institute of Technology,
Harbin, China What is the background for this study? What are the main findings?

Response: Self-healing materials and coatings are smart solutions to environmental and energy problems. There are heavy demands for these materials in many productions such as consumer electronics, the automotive industry and healthcare.

Current coatings that can self-heal are typically soft. This means they are not as anti-scratch as rigid surfaces and the benefit of the ability to repair themselves could be overwhelmed by their limited robustness vulnerable to normal mechanical contact. It would be very useful to have a self-healing coating with a hardness that can be comparable or even outperform rigid coatings. This is normally difficult because mechanical hardness and self-healing are two conflicting properties with the opposite dependence on polymer dynamics. One good example in this context is many soft tissues can self-heal, but a notable exception is tooth enamel, which is the hardest part in our body but has no way to recover after decay. A new design will be needed to circumvent the fundamental limitation.

We find that by mimicking the structure of epidermis, it is possible to combine two contradictory properties into an artificial coating, namely, self-healing ability and high hardness. The success relies on the placement of a hard layer containing graphene oxide on top of a soft sublayer with a seamless interface for interlayer diffusion. This allows a similar healing mechanism as that in skin, but the coating is not soft and has a hardness that even approaches tooth enamel. What should readers take away from your report?

Response: Each time when you learn from Nature, you will get something. In this study, we show that a better coating can be obtained via a multilayer design that Nature has used in many living structures such as skin and bones. While nature’s design follows rules of evolution, the artificial creation must have its limitations. Other key characteristics of the coating structure such as adhesive properties need to be verified. Fillers other than graphene oxide may be used instead to improve the transparency of the coating. We will also need to find a more time-efficient and industrially scalable way as a substitute for molecular assembly used in the current study. What recommendations do you have for future research as a result of this work?

Response: I believe the concept we proposed in this study to mimicking the structure of epidermis can be readily used for other polymer systems. When the same design is used for polymers that can response to stimulus such as heat and light, new dental restoratives may become possible. The use of this novel material as medical device coatings may be another possible direction to go especially considering its added antibacterial properties.

No disclosures


An Epidermis-like Hierarchical Smart Coating with a Hardness of Tooth Enamel

Xiaodong Qi†, Dan Zhang‡, Zhongbao Ma†, Wenxin Cao§, Ying Hou†, Jiaqi Zhu§, Yang Gan‡ , and Ming Yang*

Key Laboratory of Microsystems and Micronanostructures Manufacturing, School of Chemistry and Chemical Engineering, and §Center for Composite Materials and Structures, Harbin Institute of Technology, 2 Yikuang Street, Harbin 150080, P. R. China
ACS Nano, Article ASAP
DOI: 10.1021/acsnano.7b05478
Publication Date (Web): January 31, 2018

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