Abstract
Objectives
This study aims to develop a bio-inspired nacre-like glass flake/polymer composite with enhanced mechanical properties, antibacterial function, and aesthetic appearance for potential dental applications.
Methods
Self-assembly via vacuum filtration was used to align glass flakes into a layered structure. After heat treatment, monomers containing methyl methacrylate (MMA), acrylic acid (AA) and dimethylaminohexadecyl methacrylate (DMAHDM) were infiltrated into the glass flake scaffold and polymerised in situ. The nacre-like microstructure of the composites was characterised and mechanical tests, including flexural strength, elastic modulus and fracture toughness, were conducted to optimise the DMAHDM content (0, 1.5wt%, and 3 wt%). The antibacterial function of the optimised composite with 1.5 wt% DMAHDM was measured by viable colony-forming unit (CFU) count. Finally, the translucency of the composite with 1.5 wt% DMAHDM was determined.
Results
The glass flake/polymer composites with different DMAHDM contents all exhibited nacre-like layered microstructures. Adding 3 wt% DMAHDM was shown to significantly lower the flexural strength of the composites. The composite with 1.5 wt% DMAHDM exhibited a flexural strength of 126.97 MPa, comparable to the current benchmark aesthetic dental composite. Moreover, the elastic modulus of the composite with 1.5 wt% DMAHDM (24.75 GPa) was similar to that of human dentine, presenting bio-inspired mechanical property. Its unique crack resistance, characterised by a rising R-curve behaviour and a fracture toughness KJ up to 3.88 MPa.m½, suggested excellent damage tolerance. With the addition of 1.5 wt% DMAHDM, the nacre-like composite demonstrated significant antibacterial function against Streptococcus mutans. Furthermore, the composite retained an aesthetic appearance with a translucency comparable to human enamel.
Significance
A bio-inspired nacre-like glass flake/polymer composite with good mechanical properties, unique crack resistance, antibacterial function and translucency has been developed for aesthetic dental applications.