Tougher, lighter dental implant crowns

A research group from VTT Technical Research Center of Finland, in collaboration with Nanyang Technological University, developed a sustainable, multiphase nanocomposite mimicking the peachick mantis shrimp, using it to manufacture dental implant crowns. This bioinspired material is an intermixing of birch-cellulose and a set of genetically engineered proteins. The outcome is a material that’s stronger, tougher, and substantially lighter than man-made technical ceramics, having the potential to become a next-generation material for a range of applications.

The research group was able to create an impact- resistant material inspired by the dactyl club of the mantis shrimp. The material could be used in applications that require withstanding repetitive, high strain-rate impacts while maintaining structural integrity.

“These mesmerizing shrimps are one of nature’s deadliest killing machines. In relation to their small size, they pack the strongest punch in the animal kingdom. They smash their prey by throwing a pair of hammer-like raptorial appendages with a tremendous speed and force greater than rifle bullets during close-range hunting,” explains Dr. Pezhman Mohammadi, research scientist at VTT. “The mantis shrimp’s primary sources of food are hard-shell marine organisms, such as mollusks. To get to the soft, nutritious part they obliterate straight through these highly mineralized exoskeletons.”

Earlier studies showed the shrimp club is a multiphase, hierarchically ordered nanocomposite with graded mechanical properties.

“The club has a soft interior layer providing energy dissipation and a stiff, hard, and impact-resistant exterior layer. Together, the layers enhance the overall damage tolerance of the shrimp. Both layers have similar building blocks, but in different relative content, polymorphic form, and organization. The main building block is helicoidally ordered chitin nano-fibrils that are glued together by a protein-rich matrix,” Mohammadi explains.

Combining cellulose nanocrystals, proteins

The research group replicated this structure by using similar building blocks and processing conditions, assembling a new composite consisting of cellulose nanocrystals and two types of genetically engineered proteins. One protein was designed to increase the interfacial strength of the material and the other to mediate nucleation and growth of hydroxyapatite crystals.

This composite was processed into intricate shapes by manufacturing it into a dental implant crown with periperiodic patterns of micro-reinforcement orientation, and a bilayer architecture similar to human teeth. With further investigation, the proteins could be engineered to provide new characteristics to the material.

VTT Technical Research Center of Finland LLC: https://www.vttresearch.com; Nanyang Technological University: https://www.ntu.edu.sg