Histopathological evaluation of the effect of melatonin gel on bone regeneration in rat model

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Background: The purpose of this research was to investigate the effects of different doses of topical melatonin gel on bone regeneration in rat calvarial defects using histological analysis. Materials and Methods: Fifteen adult female Wistar rats weighing approximately 200 g were used and 8 mm in diameter defects were created in their calvaria. The rats were divided into three groups: 1.2% melatonin gel, 5% melatonin gel, and the control group. The animals were sacrificed after 4 weeks. Hematoxylin and eosin staining were used to prepare histological sections. Statistical analysis was performed using the Analysis of variance and Tukey’s post-hoc test. P < 0.05 was considered significant. Results: The results showed a significant difference in rate of ossification ( P < 0.001), area of new capillaries ( P = 0.002), and mean degree of inflammation ( P < 0.001) between the three groups. Comparing groups pairwise, degree of inflammation ( P = 0.003) and area of new capillaries ( P = 0.019) were significantly lower in the 5% melatonin gel group than the 1.2% melatonin gel group ( P = 0.003). The percentage of ossification was substantially greater in the 5% melatonin gel group than in the control and 1.2% melatonin gel groups ( P < 0.001). Conclusion: Within the limitations of this animal study, our findings revealed that melatonin gel can be used as a stimulant of bone formation. Outcomes in this study show increased percentage of ossification in the melatonin groups when compared with the control, in a dose-dependent manner, as 5% melatonin gel has a greater effect on ossification.