I have had two childre, siblings of ages 4 and 7, that have presented with
black extrinsic line stains on their teeth at the gum line. The children
have great oral hygiene as to other indicators. Otherwise there was no other
finding.. caries free, no plaque/calculus, etc. These stains were easily
cleaned with simple prophy paste.

As I am aware, these stains are harmless and do not increase caries
occurance. Does any have any suggestions to the source of this stain?

Sources that I can think of:

- Iron supplements (they do not take any)

- Tea, Coffee, Tobacco (not present in this case)

- Chlorhexidine (do not take)

Any other possible comon sources?

Thanks in advance