Help! haven't worn invisalign in about 3 months! is it safe to wear it again?

Maybe: Did you save your old aligners? You might have to back way up to findan earlier aligner that fitsthen you can move along normally. If you dont have thealigners your dentist can order them for you. Good luck this time.

Not Now: Before you continue with your treatment after a 3 month layoff, please, please go back to your treating doctor. Only he/she can make that determination of what you can do, where you are in treatment, and whether or not there has been setbacks/relapse.

Likely not: I would go see your orthodontist asap to get new trays fitted.

If you can get it on: But, don't plan on stability if your teeth were crowded before treatment. Invisalign is just another expansion appliance. The meta-analysis shows that when teeth are moved toward the muscles of the face they are like a slingshot. Once you let go of the retainers, the muscles return to their original resting length (muscle spindles). It is like letting go of the slingshot. They push them back.

Reevaluation: Going without appliances for that long probably means there has been some relapse. You should be reevaluate and a new series of trays constructed based on the new set of data. Please see a fully qualified Orthodontic Specialist for reevaluation.