Biphasic calcium phosphate doped with zirconia nanoparticles for reconstruction of induced mandibular defects in dogs: cone-beam computed tomographic and histopathologic evaluation.

The present study aimed to evaluate osteogenic potential and biocompatibility of combining biphasic calcium phosphate with zirconia nanoparticles (4Zr TCP/HA) compared to biphasic calcium phosphate (TCP/HA) for reconstruction of induced mandibular defects in dog model. TCP/HA and 4Zr TCP/HA scaffolds were prepared. Morphological, physicochemical, antibacterial, cytocompatibility characterization were tested. In vivo application was performed in 12 dogs where three critical-sized mandibular defects were created in each dog. Bone defects were randomly allocated into: control, TCP/HA, and 4Zr TCP/HA groups. Bone density and bone area percentage were evaluated at 12 weeks using cone-beam computed tomographic, histopathologic, histomorphometric examination. Bone area density was statistically increased (p < 0.001) in TCP/HA and 4Zr TCP/HA groups compared to control group both in sagittal and coronal views. Comparing TCP/HA and 4Zr TCP/HA groups, the increase in bone area density was statistically significant in coronal view (p = 0.002) and sagittal view (p = 0.05). Histopathologic sections of TCP/HA group demonstrated incomplete filling of the defect with osteoid tissue. Doping with zirconia (4Zr TCP/HA group), resulted in statistically significant increase (p < 0.001) in bone formation (as indicated by bone area percentage) and maturation (as confirmed by Masson trichrome staining) compared to TCP/HA group. The newly formed bone was mature and organized with more trabecular thickness and less trabecular space in between. Physicochemical, morphological and bactericidal properties of combining zirconia and TCP/HA were improved. Combining zirconia and TCP/HA resulted in synergistic action with effective osteoinduction, osteoconduction and osteointegration suggesting its suitability to restore damaged bone in clinical practice.