Abstract
The clinical failure mode of dental crown ceramics involves radial cracking from the flexure of the ceramic layer on the subsurface. This results in a reduced lifespan for the majority of the dental crown, and thus research has focused on the optimal material combinations that can reduce stress concentration in dental ceramics for more efficacious application and as such, successful commercialisation in the future. A bioinspired ceramic composite is a potential superior alternative to traditional dental ceramic materials as it not only exhibits improved fracture toughness, but offers a prospective cost-effective substitute, such as for dental in-direct restorations and prosthetics. Bi-directional freeze casting is a promising technique that could be utilised extensively in ceramic composites to overcome challenges regarding brittleness, toughness and strength. This research aims to optimise freeze-casted bioinspired composites that can be used as a strong and tough ceramic-based dental crown. Thus, freeze-cast, bioinspired and multilayer alumina (Al2O3) composites with four different polymer phases were in situ tested to evaluate their bending behaviour and fracture toughness. In addition, a computational model was utilised and validated against experimental results. Based on the experimental evidence and numerical modelling, it was concluded that bioinspired ceramic-based composites showed superior strength and toughness compared to current commercial all-ceramic materials. Variability in mechanical properties occurred mainly on account of differing microstructure and volume fractions of compositions i.e., 60 vol.% Al2O3/PMMA displayed superior toughness and a greater extent of toughening mechanisms. Hence, developing reliable, advanced in situ, micromechanical characterisation techniques and establishing complex multiscale numerical models are critical for successfully passing hurdles in the dental field.