Tooth enamel: hard, and hard to replace
The hardest substance in our body is tooth enamel. That makes good design sense given the rugged and abrasive forces our teeth often have to withstand during a lifetime of biting and chewing.
The natural biomineralization process that produces tooth enamel’s “complicated and well-aligned apatite structure”1 involves cells called ameloblasts. They produce special proteins that harden into the famously tough external coating of our teeth.2
But ameloblasts are only present during tooth development.3 So, mature enamel is “scarcely self-repaired after damage”.1 Thus if we are slack in our dietary habits and mouth hygiene, then caries (dental decay) can strike, with lasting consequences! Sure, dentists currently use various materials as fillings (e.g. amalgam, composite resins, and ceramics). However, these foreign materials do not always adhere well to the native enamel or dentine, and can become loose.
Hence the scientific quest to copy tooth enamel. But even after many years of research effort, no-one could satisfactorily mimic natural enamel’s complicated hierarchical structure in the lab. Now, however, a research team co-led by biomimeticist Zhaoming Liu of Zhejiang University, China, claims to have made a breakthrough.1,4 By an ingenious method involving the coating of volunteers’ teeth with a gel containing calcium phosphate ion clusters, they managed to generate a thin (2.7 microns) layer of enamel over a 48-hour period (as shown in the pictures). Of course, to match natural tooth enamel’s thickness and to tackle cavities, the researchers must improve on this by several hundredfold. They are working on this and hope to clinically trial “tooth enamel regrowth without using fillings” within two years.3
In the meantime? “Prevention is the best approach,” advised biomedical researcher Haifeng Chen, of Peking University. “We should never wait until the damage is done. Our teeth are a miracle of nature. Artificial replacement will never do the job as well.”3 Good practical advice; however our teeth are not a miracle of nature, but of God, actually.
References and notes
- Shao, C., and 11 others, Repair of tooth enamel by a biomimetic mineralization frontier ensuring epitaxial growth, Sciences Advances 5(8):eaaw9569, 2019. ‘Apatite’ is the name of the group of phosphate minerals (enamel consists of phosphate minerals). Return to text.
- Although extremely hard, enamel is actually as brittle as glass, but the external covering of our teeth has a number of design features that prevent propagation of any cracks. See Sarfati, J., Tooth enamel: sophisticated materials science; creation.com/enamel, 14 May 2009. Return to text.
- Dockrill, P., Scientists have developed a genius method that actually regenerates tooth enamel; sciencealert.com, 3 September 2019. Return to text.
- Davis, N., Scientists discover way to ‘grow’ tooth enamel; theguardian.com, 31 Aug 2019. Return to text.