Decay under crown or something else

[Katie7730]

I had a root canal and crown done by dentist 1 on a molar about 18 months ago. No further mention of any problem with it. Including X-rays about 6 months after that.
Today I went to a new dentist who took X-rays for a check up. He showed me a tiny black piece that’s under the crown. He said he can’t tell if it’s decay or something else. I asked him what he meant, and he said the edges looked very straight so it might be filling material.
Does this sound right? I’m a bit confused and didn’t ask any further questions.
He said it’s best to watch it and X-ray it again in a year to see if it changes or not. Does this sound ok? I thought fillings showed up as white on X-rays. I’m a bit worried .
Many thanks

 

[Gordon]

Not all filling materials show up white, some of the glass ionomers for instance. I completely agree with your new dentist, watch and wait seems the best thing to do.

 

[Katie7730]

Not all filling materials show up white, some of the glass ionomers for instance. I completely agree with your new dentist, watch and wait seems the best thing to do.

He said something about cement or materials but I tend to panic and not take everything in and then forgot to ask the questions when I don’t understand! Thanks a lot Gordon

 

[Gordon]

It could well be cement, again some of them are radiolucent (come up black on films), it's much easier to ask questions on here when you've got time to think about things