> What causes black lines on gums? I have had them since I was a kid, and
> none of my dentists ever said anything about it. If I give a big grin,
> you can see black lines going across my gums in the front and parts of
> the sides of my mouth. I can also see them at the bottom of my mouth on
> one side under the molars. I never had any dental implants of any kind.
> I'm 30 now.