I think everyone is forgetting that eternity is just that: eternal. The sun, however, is not. In fact, the sun will last only a teeny-weenie fraction of eternity. Actually, in terms of eternity, the sun is a very transient phenomenon - what's another 4 billion years or so when you're staring eternity in the face?
The wear rate of teeth is nothing compared to the sun's life. And our type of sun will, in its death throes, turn into a Red Giant with a diameter almost as big as our entire solar system. This is a much more pressing problem than teeth, I assure you.
And another problem with eternal life on a paradise earth, the sun problem aside, is boredom on the one hand and governance on the other. Perfect people need no governance, no governing body. And in just ONE billion years, there will be nothing that every human hasn't done at least ten times.
Just as steak everyday quickly becomes boring, life everlasting on a paradise earth will become just as boring. Think of the most beautiful sexy person you can think of. If that person was yours, it would become boring after awhile, too. Remember, no matter how beautiful she is, no matter how sexy, there's some guy some where who's tired of putting up with her shit.
No, it's not teeth that will be the real problem. IMHO, it will first be the insult of just the mere idea that a perfect people need governance, secondly boredom, and ultimately a dying sun that will make of the "perfect" earth a cinder.
All of which pales in comparison to the concept of a God who is so unimaginative that the best he can think of is eternal life on this dust mote, when an entire universe of universes beckons beyond the stars of our local universe. A God with no imagination, imagine that.