Wow. Crappy orthodontist. How could they not realize that was happening or going to happen?
The first year, my teeth didn't move at all. The orthodontist was considering full blown head gear to get some movement out of them. As it was, the pain was excruciating with each visit. By about nine months in, they were doubling the bands and putting in heavier gauge wire. I didn't get movement until about month twelve. Then they finally "relaxed" with the band doubling ---That which is odiferous and causeth plants to grow---.
After the second year, my orthodontist actually retired and a new one came in. The first six months of year three was basically a wash as he figured out what was going on with my teeth. By then, I was already in college and my visits expanded from once a month to once every two or three months.
I don't think anybody noticed because it would never show up on an X-ray and the tooth was wrapped from crown to gum with the band. I'm not sure how they figured out to leave it when they were removing my braces. I guess dissolving the glue or whatever it was makes them look a little closer.

Having the retainer absolutely sucked
ass though. I had two. My first was "clear" and more or less acceptable. When it came time to replace it, they couldn't do the clear anymore and I got stuck with a red sparkly ---That which is odiferous and causeth plants to grow--- thing. I absolutely hated that thing. Imagine being in college and trying to discreetly remove a huge ---smurfing--- red sparkle retainer on date. ---smurfing--- impossible.
Thatr's strange. You would expect the orthodontist to be liable for the damage. Didn't you sue him?
That thought had occurred to me. But the question came up as to who was responsible? The orthodontist who retired or the guy who finished the work? When I pressed the issue with my mother (who had actually paid for the work), she refused. Didn't want to pay the lawyer for it. Oh well. Insurance covered the work for the most part.