How can I tell if a filling is going to fall out?

What are the symptoms? I had a very very large filling put in almost 3 years ago. At my last dental visit (July '07), the dentist said that it was a "perfect little filling" and that the tooth didn't appear to have any problems. That filling, though, seems to attract junk. It always gets "dirtier" than the other teeth. The edge of the filling is very distinct from the edge of the tooth. I'm worried that means it's about to pop off, although it's been that way for over a year (even when I went to the dentist). There is zero pain (aside from hot/cold sensitivity which I have in all my teeth, so it's a very bad indicator). I'm very worried about it coming out, since dental insurance doesn't kick in until July and my husband just lost a filling himself.
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your dentist is the expert, and if he said it was okay, it is. its not something to worry about. the chances of a filling popping out is very slim.
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