Interesting. I still believe that's what caused mine too. I was actually going through a lengthy Invisalign orthodontia plan when I was diagnosed. During the earlier stages of the treatment, I'd had "hooks" on the inside of two lower molars, and the braces had little extensions that hooked over these. My lesion was exactly aligned with where one of those had been, and I recalled that it had rubbed occasionally to the point of slight bleeding. The doctor I went to for my 2nd opinion agreed that this could have been the cause, but also said that the bleeding might have been due to having the lesion there, vs. my theory and that there was just no way to know. My lesion was very small, caught very early, and the timing was right for that to have been a factor. I'm also now very watchful of any trauma to my oral tissue.