Effectiveness of Reinforced 45S5 Bioglass with Yttria-Stabilized Tetragonal Zirconia and Iron in the Regeneration of Rabbit Calvarial Defects

Large bone defects caused by various conditions or diseases still remain one of the most challenging issues to be addressed in both human and veterinary orthopedics. Conventionally, bioglass 45S5 has been applied to reconstruct large bone defects. We fabricated yttria-stabilized tetragonal zirconia-bioglass 45S5 and iron-bioglass 45S5 composite powders to enhance osteoconductive and osteoinductive effects of conventional bioglass 45S5 in rabbit calvarial bone defects. First, these composite powders were analyzed via different in vitro analyses. For in vivo study, four circular calvarial defects of 10 animals were randomly filled with yttria-stabilized tetragonal zirconia-bioglass 45S5, iron-bioglass 45S5, and bioglass 45S5 powders or left without any treatment. Diagnostic imaging techniques and histological evaluations were conducted to assess all bone defects in different experimental groups. The cell viability and cytotoxicity analysis showed that there was no significant cytotoxic effect associated with 5 and 15 mg/mL of yttria-stabilized tetragonal zirconia-bioglass 45S5, iron- bioglass 45S5, and bioglass 45S5. In vitro results showed that the expression level of osteogenic markers increased in yttria-stabilized tetragonal zirconia-bioglass 45S5 (osteocalcin: 2.56-fold and alkaline phosphatase: 2.68-fold) and iron- bioglass 45S5 (osteocalcin: 2.44-fold and alkaline phosphatase: 3.84-fold) composite when compared to bioglass 45S5 (osteocalcin: 1.32-fold and alkaline phosphatase: 2.04-fold) and control group. The in vivo experiments confirmed the in vitro results and showed that iron- bioglass 45S5 (bone ingrowth%: 85.4 and bone volume/total volume%: 60.2) significantly enhanced new bone formation followed by yttria-stabilized tetragonal zirconia-bioglass 45S5 (bone ingrowth %:73.2 and bone volume/total volume (%): 53.4) when compared to bioglass 45S5 (bone ingrowth %: 35.6 and bone volume/total volume (%): 31.4) and untreated controls (bone ingrowth %: 17.2 and bone volume/total volume (%): 10.6). Based on the present results, yttria-stabilized tetragonal zirconia- and iron successfully increased the bone regenerative capacity of bioglass 45S5 which could be used as new additives in future commercial bone cement. Cite this article as: Jalili, M., Tabatabei Naeini, A., Ahrari Khafi, M. S., Mys, K., & Khoshzaban, A. (2022). Effectiveness of reinforced 45S5 bioglass with yttria-stabilized tetragonal zirconia and iron in the regeneration of rabbit calvarial defects. Acta Veterinaria Eurasia, 48(1), 35-47.