Assessment of K-Fluorrichterite As A Load Bearing Bone Substitute

Objectives: This research is aimed at evaluating modified potassium fluorrichterite glass-ceramics in vitro and in vivo, for load bearing applications in craniofacial surgery Methods: Three compositions based on potassium fluorrichterite; the stoichiometric compositions (GST) and two modified compositions (GC5, GP2) were selected on the basis of their mechanical properties and potential bioactivity. They were characterized using XRF, DTA and XRD. In vitro biocompatibility was assessed by solubility measurement, ionic release and cell culture. In vitro osteoconductivity was assessed by immersion in simulated body fluid while in vivo evaluation was carried out using the rabbit femur. Results: XRF confirmed pre and post melt compositional differences, especially fluorine and p2o5 concentrations. XRD indicated that these compositions could be centrifugally cast without altering their crystalline structure. Solubility assessment showed that GST was the least soluble, followed by GC5 and GP2. Ionic release from GST was also relatively low but GC5 leached significantly greater amount of ions, when compared to GP2. Cell culture showed good biocompatibility and no cytotoxicity. In vitro osteoconductivity assessment (SBF), predicted that GST, GC5 and GP2 were all osteoconductive, which was confirmed in vivo osteoconductivity assessment indicated that GST, GC5 and GP2 were all osteoconductive in vivo with evidence of intimate bony contact between the test specimen and cortical bone at 4 weeks and 12 weeks following surgery. Histomorphometric analysis demonstrated that the 45S5-type bioglass specimen (reference material) exhibited statistically greater bone to implant percentage contact at both 4 and 12 weeks, when compared to the test compositions but there were no significant differences between the test compositions themselves. Conclusions: These experiments indicate that modified potassium fluorrichterite compositions were biocompatible and osteoconductive in vitro and in vivo. Together with its previously published good mechanical properties, they represent a family of glass-ceramics suitable for load-bearing applications in craniofacial surgery.