Beyond Bioactive Glass Composition: Using Morphology to Improve in Vitro and in Vivo Performance

Compared to compositional functionalization with therapeutic ions, changing bioactive glass (BG) morphology, i.e., the size, shape, and surface structure of BG specimens, is typically not considered as an influential factor for improving performance. However, it has a large influence on the outcome of various experiments, particularly those studies where the material comes in contact with aqueous solutions, including acellular immersion studies, in vitro experiments using cells or bacteria, and even animal experiments and clinical studies. One major aspect is the surface area to volume ratio, the rate at which ions are released from the glass and surface layers, including apatite layers, forming, can be tailored to subsequently influence the behavior of cells and bacteria. By varying surface roughness or patterning, the orientation and alignment of cells can be controlled or the adhesion of bacteria can be prevented, both in vitro and in vivo. Taken together, this review shows that BG morphology is an important parameter to consider when designing experiments or developing clinical products.