Recent trends in design, manufacturing and challenges of bone-like bioceramic scaffolds

Biomaterials are often produced in the form of porous scaffolds acting as templates to allow tissue growth and regeneration in 3D. Structural biomimicry is a commonly-followed criterion so that the scaffold can replicate the trabecular architecture of bone. This is a particularly difficult task when bioactive ceramics and glasses are used for osseous applications due to some challenges related to the inherent characteristics of the materials and relevant fabrication processes (e.g. reproducibility, reliability and the need for consolidation via high-temperature sintering). Recent progresses in the advanced manufacturing of bioactive ceramics and glasses have allowed researchers to overcome some of these limitations. Given such a scenario, this review paper – which is organized in four major sections – aims to critically discuss the strategies to optimize bioceramic scaffold design and evaluate its suitability for bone applications. After an introduction to the context, section 2 provides an overview of the requirements that a porous bioceramic scaffold should ideally fulfil. Different options for scaffold fabrication, ranging from conventional methods to additive manufacturing technologies, are critically discussed in section 3. Section 4 is addressed to the strategies developed to integrate the design of bone-like structures, also driven by computational tools, into additive manufacturing methodologies. Section 5 focuses on how quantifying the “bone similarity” of scaffolds or, more generally, how assessing if a scaffold is truly suitable for bone applications; advantages and limitations of the current approaches are discussed along with an outlook for future challenges.