Question

1. Calcium phosphates (with varying chemistry, including apatite variants) are inorganic mineral compounds used in biomaterial design. Two examples of their use are as a coating on hip implants and in helping regenerate bone. Comparing these two examples, discuss in up to 250 words how the same type of material is used in quite different ways, emphasising the differences in (biological or functional requirements) AND (structure and material properties

Answer 1

More than twenty years ago, hydroxyapatite i.e calcium phosphate ceramics, was introduced as a coating for cementless hip prostheses. This ceramic is biocompatible, bioactive, and osteoconductive. These qualities facilitate the primary stability and osseointegration of implants. It was found that calcium phosphate biomaterials, only with specific physicochemical properties, induce bone formation in non-osseous sites and therefore are osteoinductive.

Calcium phosphate has been widely used in bone regeneration applications because it shows osteoconductive and in some cases osteoinductive features. The release of calcium and phosphorus ions regulates the activation of osteoblasts and osteoclasts to facilitate bone regeneration. Thus calcium phosphate biomaterials guide new bone formation, form a tight bond with the newly formed bone, and are, therefore, by definition, osteoconductive.