Bioceramics: An Overview

Bioceramics are biocompatible ceramic materials used in medical restoration and repair. Their microstructure depends on processing parameters that ultimately result in the final product’s specific mechanical, thermal, and biological properties. Structural bioceramics are used in load-bearing applications, while bioactive ceramics enhance the surface properties of implants, particularly in combination with bone growth-supporting proteins. Among structural bioceramics, alumina has been extensively used for femoral heads and acetabular cups in total hip arthroplasty because the material can be engineered to achieve the necessary toughness and durability. Likewise, changes in the composition and processing of zirconia ceramics can tailor this bioceramic to specific applications, such as dental implants and veneers. The limitations and advantages of carbon-based materials have been investigated for use in heart valves, and wear-resistant coatings for articulating implants. Silicon nitride uniquely straddles the gap between bioinert and bioactive ceramics. It has both load-bearing capability, as well as surface bioactivity that facilitates bone ingrowth. Bioactive ceramics such as hydroxylapatite are unsuitable for load bearing but are being used successfully as osseoconductive coatings on metal implants, with the goal of improved biological behavior. The wide range of available bioceramic materials today will almost certainly expand as many novel material options are explored for medical uses. However, considerable work and expense are required before any new candidate bioceramic makes it to successful commercial use.