Dental News - Parrotfish tooth research may ring in new era of biomaterial development

Dental Tribune International

Fri. 10. November 2017

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SINGAPORE/BERKELEY, Calif., U.S.: The achievements of science are evolving constantly. However, there are many natural wonders that humanity has not been able to mimic yet. Among these are parrotfish teeth, which are one of the strongest and most abrasion-resistant in the animal world. Investigating their structural make-up, a team of researchers has now determined the underlying properties that make the fish’s teeth strong enough to even bite stony corals.

“Parrotfish teeth are really good all-round biters of hard things, and few other teeth in nature are harder or stiffer,” said lead author Dr Matthew Marcus from the Lawrence Berkeley National Laboratory in California. To feed, the investigated steephead parrotfish Chlorurus microrhinos bite off corals and assimilate the organic material within it. To do so, these fish have two sets of teeth: one for biting corals and a pharyngeal set for grinding and chewing the bitten-off material.

Aiming to find out what makes the fish’s teeth so resistant, the researchers first measured their mechanical properties in nano-indentation experiments. Afterwards, they performed chemical analysis with a variety of techniques, including scanning electron microscopy with energy-dispersive X-ray analysis and electron probe micro-analysis.

As reported by nanotechweb.org, the results showed that it is not the material of parrotfish teeth that is special, but the arrangement of the crystals of the teeth. Studying the structure, the researchers found that the enameloid nanocrystals co-orient and assemble into bundles interwoven like the warp and weft threads in fabric. The fibres gradually decrease in size from 5 μm at the back to 2 μm at the tip, and according to Marcus, it is this size decrease that makes the tooth structure so hard.

“The results also show that in nature, complex structures have evolved to carry out specialized extraordinary functions, like biting coral, using simple, unsophisticated materials,” Marcus told nanotechweb.org. “Man-made materials, in contrast, usually do the opposite—that is, we use high-tech materials with a very basic structure.”

According to the researchers, the techniques used in the study could be employed to study human bone and teeth more thoroughly and help in the development of new biomimetic materials.

The study, titled “Parrotfish teeth: Stiff biominerals whose microstructure makes them tough and abrasion-resistant to bite stony corals”, was published online ahead of print on 20 October in the ACS Nano journal.