Melatonin (N-acetyl-5-methoxy tryptamine) is a substance secreted by multiple organs including the pineal gland, retina, bone marrow, the gastro-intestinal track, and the immune system. Its main function is the regulation of the circadian rhythm (day-night cycles). It plays an antiinflammatory, antioncotic, and immunomodulatory role by scavenging free-radicals and via interactions with cell membrane and intracellular proteins. Melatonin is capable of entering the oral cavity by diffusing into the saliva from blood. As the majority of the melatonin remains bound to serum albumin, the amount of melatonin in saliva is approximately one third of that present in the blood . Melatonin mainly exerts antioxidant effects by interacting with melatonin receptor 1 (MT1) and melatonin receptor 2 (MT2) receptors on cells. Perhaps, a potent antiinflammatory property of melatonin is linked to its ability to act as a scavenger of exogenous and endogenous reactive oxygen species (ROS) and reactive nitrogen species (RNS). In addition, both ROS and RNS have been associated with DNA mutations leading to carcinogenesis. The existence of MT1 receptors on healthy and cancerous oral mucosal cells is suggestive that melatonin may act as an antiinflammatory or antioncotic agent in the oral cavity; for example, its antiinflammatory effects have been reported on human gingival fibroblasts. Furthermore, intraperitoneal melatonin has been reported to reduce periodontitis in diabetic rats. Similarly, topical application of melatonin in diabetic patients has diminished the progression of periodontal bone loss as evident by the down-regulation of proinflammatory factors. Hence, it has been suggested that melatonin may be used in the management of periodontitis and antioncotic agents for oral cancer cells. The aim of this review is to critically analyze and summarize the research focusing on the potential of melatonin in the fields of oral medicine and periodontology.
