Background and Aim: Fracture cases significantly increase recently, demanding high quality of bone graft materials. This research aimed to evaluate the effects of bone types, particle sizes, and gamma irradiation doses on morphological performance and cell viability of feline demineralized freeze-dried bone allograft (DFDBA) through an in vitro study.

Materials and Methods: Feline DFDBA derived from feline cortical and cancellous long bones was processed into four different sizes: Group A (larger than 1000 μm), B (841-1000 μm), C (420-840 μm), and D (250-419 μm) for each type of bones. The materials were then irradiated with two doses of gamma rays, 15 and 25 kGy, resulting in 16 variants of feline DFDBA. The surfaces of each material were then observed with the scanning electron microscope (SEM). The in vitro evaluation of feline DFDBA was then performed using 3-(4,5-dimethythiazol-2)-2,5-diphenyltetrazolium bromide (MTT) assay with calf pulmonary artery endothelial cells.

Results: The MTT assay results showed that the lowest inhibition rate (14.67±9.17 %) achieved by feline DFDBA in Group A derived from cortical bones irradiated with 15 kGy. Group D generally showed high inhibition rate in both cancellous and cortical bones, irradiated with either 15 or 25 kGy. The SEM results showed that cancellous and cortical bones have numerous macropores and micropores structure in 170× and 3000×, respectively.

Conclusion: The material derived from cortical bones in Group A (larger than 1000 μm in particle size) irradiated with 15 kGy is the best candidate for further development due to its abundance of micropores structure and ability in preserving the living cells.

Keywords: bone type, feline bone allograft, gamma irradiation, in vitro study, particle size.