My own suggestion is to return to your dentist (it may be dealt with by a phone / email consultation) and I agree, up to a point, with @janeainsworth.
If it is not affecting or bothering you, then there may be no point in considering any investigation / treatment. However, the dentist may think it needed one of those things.
In that case, they should, as said, have treated / referred you BUT they may have felt a GP could deal with it better. If any health professional says 'see your GP' then ask for a letter. That is a more efficient use of everyone's time.
I would also say that in more recent times, various commissioning groups (I completely lose track) have different pathways within the NHS. Even before I retired in 2010, I was aware of inappropriate referrals being made - not because the professional concerned didn't understand the basic issue, but because they didn't understand the way the local system worked.
Even more reason to ask for a letter.
Hope you get it sorted.