My dentist instructed me to wear my invisalign trays for 12 days each (22 hours a day). Shouldn't it be 14 days instead of 12?

Although most treatment plans are based on a two week aligner wear (14 days) and Align Technology bases much of their treatment planning on that two week interval, there is nothing magic about the 14 days. Sometimes when my patient needs elastics (rubber bands) worn, I could have them wear the aligners for as much as four weeks. A 12 day routine is not much different than the 14 days, but the key is to follow your dentists advice and ask him/her to explain if it doesn't make sense to you.

there are reasons to alter the aligner timing and time frames. Is your provide a dentist or an orthodontist? It makes a difference.