Hi. I have 4 gold crowns on my first molars. The orthodontist originally just glued the brackets on them. Slowly, I have had to have the bracket replaced twice on three of them. The second time around, he banded them. As for needing new crowns. My dentist said I would probably need some new crowns when all was done. I mentioned this to my orthodontist last time I was in and he didn't think I would need to replace any of them. He said it was like buy a Spam to replace a Ford - money... Since he is aware that money is an issue for me, he is working to keep what I have (although, I think he would have done that anyway).
But, that said, I am sure it depends on each individual and what all has to be done to correct the bite.
Had Damon 3 / Smart Clips for almost 2 years
Now in Hawley upper 10 hours/day, permanent lower retainers