eh.. not really known everywhere. There are hundreds of honors societies, and no one gives a $hit about them. I think your grades speak volumes compared to some stupid honors society.
But!! if you are invited to one, pay their stupid fee and join. It won't hurt to have it on your resume and dental school application.
I got invited to one of those things and didn't really bother paying the fee. If you are an active member in some honorary, then it I'm sure it would look good because it's an extracurricular, but if you just sit there after paying a fee it's not really that useful. It seems like the requirements weren't that hard to meet to get an invite.