Background and Aim The use of allograft alone or in combination with other bone materials has significantly improved bone-augmentation procedures. Therefore, this study aimed to evaluate the effect of topical gentamicin solution (80 mg) with allograft on guided bone regeneration in defects in rat skull. 
Methods & Materials Twelve Wistar mice were randomly divided into two groups, with 6 in each group. Three defects were created in their skulls, one filled with demineralized freeze-dried bone (DFDBA) allograft alone, the other with allograft with gentamicin 80 mg solution, and the third defect were left empty as a control group. After 4 and 10 weeks, the mice were killed for histological specimens. Histological and histomorphometric evaluations were performed to qualitatively and quantitatively assess bone formation, a new bone type made, new bone vitality, inflammatory response, connective tissue type, and angiogenesis.
Ethical Considerations This study was approved by the ethics committee of Arak University of Medical Sciences (Code: IR.REC.ARAKMU.1397.30).
Results At the end of 4 and 10 weeks after surgery, the average percentage of ossification in the area of ​​defects was higher in the group that received allografts with gentamicin, and during this period, a significant difference was seen between these groups and the control group.
Conclusion According to the present study, the use of gentamicin in combination with DFDBA has a significant effect on bone regeneration in defects in the rat skull.