Preliminary evaluation of therapeutic ion release from Sr-doped zinc-silicate glass ceramics

Bioactive and degradable porous bioceramics play an important role in many clinical situations. Porosity is essential to the performance of a material that is proposed to be used as an implantable osseous scaffold. Scaffolds provide a three dimensional support and template to osseous integration and vascularization. Combining the porosity of a scaffold with the ability of the scaffold material to deliver therapeutic ions to the site of implantation goes some way towards developing an ideal bone graft. A series of strontium-doped zinc silicate (Ca-Sr-Na-Zn-Si) glass ceramics scaffoldswere developed, whose porosity was measured to be between 93% and 96%, which is advantageous in terms of osseous integration and vascularization. The levels of Zn ²⁺ and Sr ²⁺ detected as a result of degradation of the crystalline phases were found to be 1.4–600 parts per million (ppm) and 0–583 ppm, respectively. The levels detected correlate well with the levels of Sr ²⁺ and Zn ²⁺ ions typically associated with clinical benefits, including antibacterial efficacy, osteoblastic differentiation and impaired osteoclastic resorption.