Brief Answer: Tartar deposition. Detailed Answer: Hello, Thanks for posting your query. The black line at the junction of the teeth and gums is seen most commonly due to a deposition of tartar on the roots of the teeth adjacent to the gum line. Tartar is a calcified deposit that must be regularly removed by professional dental cleaning, in order to maintain gum health. Do consult a dentist to confirm this and get it removed. A true darkening of the gums may be due to normal melanin pigmentation, especially in dark-complexioned individuals. Less commonly, discoloration of the gum margins is seen in cases of excessive levels in the body of heavy metals, such as cadmium, mercury, lead, or silver. In these cases, consultation with a toxicologist is indicated. I hope this answers your query. In case you have additional questions or doubts, you can forward them to me, and I shall be glad to help you out. Wishing you good health. Regards. Dr. Praveen Tayal.

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