Well, personally I think that 2 years old is too old, but I would never impose my opinion on someone about such a thing unless asked. My reasoning is that by that time it can grow to the point where the child "needs" it, and feels anxiety if they don't have it to sleep, or to do whatever they normally like to do with it. I took my son's away when he was about 4 months, because I noticed that he was just starting to panick a little when I took it away, and I thought better to get it over with now before it becomes way more of a struggle later. my daughter is now 5 months, and she just now starting to get to that point, and I'm probably going to take it way in the next month or so. I think it's just one of those, what works for you and your child type of things.
2 yr-old using pacifier..big deal? - Page 2
because if they are walking around with it all day or a good part of the day (which, yes, some two year-olds do....i had 2 out of 8 like that in my toddler class this year) it inhibits language development at and age where most kids are experimenting with words and talking. but not if you have a nuk in your mouth.
and then there's the dental issue but i don't know anything about that part.