Hydroxyapatite and tricalcium phosphate composites with bioactive glass as second phase: State of the art and current applications

Abstract

Calcium phosphates are among the most common biomaterials employed in orthopaedic and dental surgery. The efficacy of such systems as bone substitutes and bioactive coatings on metallic prostheses has been proved by several clinical studies. Among these materials, hydroxyapatite (HA) and tricalcium phosphate (TCP) play a prominent role in medical practice since the '80s. In the last years, numerous attempts to combine HA or TCP with bioactive glasses have been made. There are two main motivations for sintering calcium phosphates with a glassy phase: on the one hand, it is possible to tune the dissolution of the final system and to enhance its biological response through the synergistic combination of two bioactive phases; on the other hand, the glass acts as a sintering aid with the aim to increase the densification of the composite and thus its mechanical strength. In this sense, TCP and HA are penalized by their relatively poor fracture toughness and tensile strength compared to natural bone, which makes it impossible to use them in load-bearing applications. Moreover, the bioactivity index of pure calcium phosphates is typically lower with respect to that of many bioactive glasses. In this review, the state of the art and current applications of composites, based on HA or TCP with bioactive glass as second phase, are presented and discussed. A special emphasis is given to the processing and mechanical behaviour of these systems, together with their biological implications, as a function of the composition of the glass employed as second phase.

Novel bioglasses for bone tissue repair and regeneration: Effect of glass design on sintering ability, ion release and biocompatibility

“…In this study, the two borate-based glasses (NCL3 and NCL4) exhibited similar one-step densification behaviour, with a small sintering interval in comparison to the silicate and phosphate-based glasses [53].…”

Bone regeneration using β‐tricalcium phosphate (β‐TCP) block with interconnected pores made by setting reaction of β‐TCP granules

“…The composition of the samples was analyzed by X-ray diffraction The porosity of the sample was calculated from the bulk density of the corresponding sample and its theoretical density of β-TCP (3.07 g/cm 3 ) (Bellucci, Sola, & Cannillo, 2016;Famery, Richard, & Boch, 1994). The bulk density was determined from the weight and external volume of the samples (n = 8).…”

An Update on Bioactive Glass in Bone Tissue Engineering

“…The most widely used method involves using biomaterial scaffold with a well-defined architecture that acts as a temporary structure for the cells, which guides their proliferation and differentiation into the targeted tissue or organ. The incorporation of growth factors and some other biomolecules into the scaffold with the cells can guide the regulation of cellular functions during tissue or organ regeneration [1]. Bioactive material refers to material that can induce certain biological activity [2].…”