Rodent Teeth: Ingenious Architecture of Natural Functional Materials to Inspire Human Dentistry

Teeth are an excellent example of natural composite materials with optimally designed architectures composed of simple inorganic and organic compounds. Constantly growing, elongated rodent incisors show adaptations and optimizations that exceed those of human teeth. Rodent incisors can be recognized by their orange-brown color and their specific architecture, in which hard enamel selectively covers only the labial surface of the incisors, making them a self-sharpening device.

This study reveals the biological processes and architectural design of rodent incisors from seven species (beavers, coypus, marmots, squirrels, voles, rats, mice) inhabiting different habitats. The infusion of iron-containing ferrihydrite-like material into the interstices between the elongated hydroxyapatite crystals in the outer enamel, together with the formation of the transition zone (TZ) and surface layer (SL), represents a substantial enhancement of the outer iron-rich enamel (Fe-EN). Although the filled pockets account for less than 2% of its volume, they are believed to play a critical role in improving mechanical properties and increasing resistance to acid attack. Most importantly, Fe-EN is not the primary source of the characteristic color observed on the surface of rodent incisors, as was previously thought. Instead, the typical orange-brown coloration results primarily from the overlying SL (and TZ). The functional significance of acid-resistant Fe-EN and the understanding of the coloration generation have far-reaching implications for human health, restorative dentistry, and the development of an entirely new class of dental biomaterials with improved properties.

Publication

Srot, V., S. Houari, G. Kapun, B. Bussmann, F. Predel, B. Pokorny, E. Bužan, U. Salzberger, B. Fenk, M. Kelsch and P. A. van Aken. Ingenious Architecture and Coloration Generation in Enamel of Rodent Teeth. ACS Nano 18, 11270–11283 (2024).

https://doi.org/10.1021/acsnano.4c00578

Media appearance

Highlighted by the American Chemical Society (ACS)

ACS Newsroom, 17^th April 2024

Study finds iron-rich enamel protects, but doesn’t color, rodents’ orange-brown incisors

https://www.acs.org/pressroom/presspacs/2024/april/iron-rich-enamel-protects-but-doesnt-color-rodents-orange-brown-incisors.html

Highlight on the page of MPI for Solid State Research, 9^th May 2024

Rodent teeth inspire advances in human dentistry

https://www.fkf.mpg.de/8276889/2024_05_Srot

Highlight on the page of Max-Planck-Gesellschaft, 7^th June 2024

Rodents inspire dentistry

https://www.mpg.de/22034748/rodents-dentistry