You are required to change your Invisalign aligners every 2 weeks. It is best to do this at night time before you go to sleep. Each clear aligner is trimmed by hand so if you find a rough area this can be gently polished using a nail file. Your Invisalign aligners are individually engraved with the stage number on the molar teeth (e.g. U02 meaning upper aligner number 2). Ensure the aligner is seated down correctly over all of your teeth. Do not bite your aligners into position as this may damage them.