The fundamental units of enamel microstructure which give enamel its remarkable damage tolerance are discrete “rods” roughly 1/10th the size of a hair that extend through the full enamel thickness. However, most previous attempts to quantify the microstructure have been restricted to making inferences from two-dimensional sections of an inherently 3D structure. In this paper, we brought samples to the Advanced Photon Source at Argonne National Lab to perform synchrotron micro-computed tomography to image enamel in 3D. This allowed us to identify patterns and trends in the microstructure that are difficult to see in 2D imaging alone. These findings are essential for mimicking the hard-yet-tough performance of enamel in structural materials through 3D printing.

Fused filament fabrication was performed on commercial and experimental filaments with continuous fibers. The strength of printed carbon fiber filament decreased from 10% to over 60%, with no correlation to fiber volume fraction. For the commercial filaments, those reinforced with Kevlar fibers underwent less degradation than with carbon fibers. Fibers near the filament surface incurred damage during printing that facilitates fiber fracture at extrusion. Damage to the filament and the reduction in reliability depends on material selection, process settings and hardware. 

C. Renteria, J.M. Fernández-Arteaga, J. Grimm, E.A. Ossa, D. Arola

Dental enamel is remarkable for its ability to withstand damage over decades of constant and demanding work. For this reason, there is significant interest in using the microstructure of enamel as a bio-inspiration model for damage tolerant materials. While human teeth have been extensively studied, this paper shows that depending on whether one wants high wear resistance or high damage tolerance, looking at other mammals may provide more useful insight.