I'm not sure if this will be the case for you, but I was on minocycline for 5 years in middle school/highschool. My gums turned this blue grey color and when I had my wisdom teeth out he showed me that my teeth were black. I don't know how long it took, but after a while I no longer had the blue/grey gums and I imagine the teeth are no longer black. I have been on doxy a while now and am noticing a slight color to my gums now so I imagine they are turning again, but I am not too worried since it reversed in me before.
Post Edited (Joyful01) : 2/19/2014 10:20:33 AM (GMT-7)