Biological Test of Porous Geopolymer as a Bone Substitute

Bone substitute materials in the current use sustain several drawbacks such as donor site morbidity, induce immunity, availability, and economic production. New synthetic bone substitutes are needed that overcome these drawbacks. This study aimed to produce a porous geopolymer and evaluate its usefulness as a bone substitute. Metakaolin-based geopolymer with different porosity percentages and sizes was produced by the addition of hydrogen peroxide and olive oil in different ratios to the geopolymer paste. Image J analysis had used to calculate the porosity percentage and size. Geopolymers with the highest porosity percentage and size range were selected for in vivo testing on animals. In the in vivo study, porous geopolymer was implanted in femur bones of 12 rabbits. The right femur of each rabbit served as the positive control (using the commercial bone replacement TEEBON®), and the negative control group received no treatment. The left femur was used to implant the geopolymer. Two and four weeks after implantation, biopsies were performed for histological analysis. After two and four weeks, a histological examination of the implanted material revealed the development of bone trabeculae with minimal inflammation. As compared with commercial bone substitutes, geopolymers improved bone formation. Owing to the results, porous geopolymers could be the promising materials for bone substitutes, as they are available and cost effective.