Evaluation of the effects of local and systemic application of royal jelly with demineralized bone graft on healing of calvarial bone defects in rats

Objective: The aim of this study was to evaluate histological effects of local and systemic applications of royal jelly on osseous wound healing in a rat calvarial defect model. Materials and Methods: Eighteen male 2-months-old Albino-Wistar adult rats, weighing 250-300 g were used in the study. A total of 4 groups including a sham group (non-treatment ), a control group( only demineralized bone matrix ), local royal jelly group (demineralized bone matrix with local royal jelly-50mg/ml for 5 min ) and systemic royal jelly group (demineralized bone matrix with systemic royal jelly- 100mg/kg body weight per day for 8 weeks ) were formed. On each animal, a-5 mm diameter calvarial defect was created with a standard trephine bur in the parietal bone without damaging the underlying dura mater. To reduce the number of animal, defects were prepared bilaterally on the same rat calvaria for sham and control groups. The defects in the experimental groups only prepared on the right side of the sagittal sutures. The animals were sacrified at the end of 8th week after the surgery. The original defect area was removed from the animal's calvarium bone by en bloc resectio. New bone formation, angiogenesis and osteoblasts expressing RANKL(Receptor activator of nuclear factor kappaB ligand) were examined histologically in the sections. Results: The new bone quality and angiogenesis were significantly increased in the systemic royal jelly group when compared to the sham and control groups. The RANKL expression was significantly lower in the systemic royal jelly group than the sham and control groups' RANKL expressions. No statistically significant effect of local administration of royal jelly was found. Conclusion: Within the limits of the study, the combination of systemic administration of royal jelly and demineralized bone matrix increased the bone regeneration in the rat calvarial defect model. Further studies are needed to explain the effects of royal jelly on bone healing.