Black tooth?

[Goliath]

Hey guys,
I was watching Goliath eat his crickets and noticed one of his bottom teeth looked black. I have been treating his MBD for a few months now. He is significantly better. could this be a side effect from the liquid calcium, maybe a cavity? Do you think this causes any pain? What do you guys think?

 

[Mikew2006]

shouldnt be a cavity, unless the liquid calcium has some kind of sugar (glucose, sucrose etc)
if hes eating, i would guess its not causing him pain, but best have him checked by a vet