Materials and Methods: A number of 15 adult male New Zealand white rabbits were used in this study. Four full-thickness skull defects were created in the calvarial bone. The first defect (control) was kept unfilled. However, the second and third defects were filled with nanomaterial and using an autogenous bone, respectively. In addition, the fourth one was filled with a mixture of NCOE and autogenous bone. On the 30th, 60th, and 90th days after surgery, the blood samples were obtained and red blood cells, white blood cell, hemoglobin (HGB), hematocrit (HCT), mean cell volume (MCV), mean cell HGB, and platelets (PLT) were determined. On the above-mentioned days, the animals were sacrificed and the bone density was determined using radiography images.

Results: Based on the results, a significant difference was observed on bone formation in control (0.18 ± 0.01 mm Al equivalent), autograft (0.1 ± 0.01 mm Al equiv.), NCOE (0.12 ± 0.01 mm Al equiv.), and NCOE + autograft (0.07 ± 0.01 mm Al equiv.) defects at day 30 post-surgery (P < 0.05). Further, significant differences were found on bone density in control (0.09 ± 0.01 mm Al equiv.), autograft (0.13 ± 0.01 mm Al equiv.), NCOE (0.14 ± 0.01 mm Al equiv.), and NCOE + autograft (0.20 ± 0.01 mm Al equiv.) defects at day 60 post-surgery (P < 0.05). Furthermore, significant differences were detected regarding bone density in control (0.15 ± 0.01 mm Al equiv.), autograft (0.21 ± 0.01 mm Al equiv.), NCOE (0.22 ± 0.02 mm Al equiv.), and NCOE + autograft (0.29 ± 0.01 mm Al equiv.) defects after 90 days (P < 0.05). The results revealed that the NCOE + autograft defect had a better bone formation in all stages of the study (P < 0.05). However, no significant effect was observed on blood hematology indexes (P > 0.05).

Conclusions: Generally, based on the results, NCOE + autograft had positive effects on calvaria healing in the rabbit.