Hi, I'm on tray 14 and with the 13th tray my upper tray stopped fitting and it's getting worse. Between tray and lateral incisors is a gap that's increasing (photo). When getting tray 14 I also noticed a strong sensibility in my left canine. Even while walking. The sensitivity disappeared after a week. My orthodontist checked my teeth when I got tray 14, I told him about the gap, he saw it and just said "oh, looks like we're loosing that tooth." And told me to finish the treatment as it is.