Why is there a gap between my tooth and my aligner? (Photo)

Based on your photo, the space doesn't seem significant, but I would definitely let your dentist know about your issue at your upcoming appointment.  He/she may be able to adjust your buttons (attachments) to make the aligner fit tighter over that tooth.  Ideally, you want your aligners to be pretty snug in order for them to be most effective.  If this tooth is being left behind, then it may be best to get a mid-course refinement, instead of waiting all the way to the end of your current trays, then getting several weeks/months more of refinement trays.  My advice to you is let your dentist know at your next appointment.  Good luck to you and I hope this helps.  You can "Follow" me on Real Self to ask more questions.Sarah Thompson, DMD St. Louis, MO

A space between the tray and the tooth usually means that tooth
is falling behind in its movement. There are many factors that can contribute
to that. If the space continues to get larger the dentist might need to
consider refinement to recapture the tooth.

If you are referring to a "gap" between the edge of your tooth and the aligner, than it is an indicator that the tooth is not "tracking".  This can occur for a number of reasons.  not enough room for the tooth - some additional space may be needed for the desired movementno attachment - some types of movements may require the addition of small tooth colored buttons called "attachments" - Hard to see from photos, but looks like you already have them.not enough hours - 20-22 hr/day is ideallast few aligners- once you get over 15 aligners, even with good cooperation and attachments, the aligners can to begin non-tracking.  Refinement may be indicated.I suggest you call your orthodontist and make an appointment so he/she can determine the next best step.  Don't be discouraged, it is very common and easily resolved.