When the video came back, I saw that the whole treatment will have 17 trays(both upper & lower), my dentist extended it to 26 trays so i won't feel as painful. My dentist told me to skip a tray(from 9 to 11) and he didn't give me any explanations. When I asked the nurse, she said that my progress was good and up to speed, it's ok to skip a tray. My guess was they've lost my tray 10. Is there a problem if I skip one? or should i get it back?