Unlike traditional braces that need to be tightened every few weeks, Invisalign only uses clear, plastic aligners. However, when first receiving your trays or switching them out to a new set every 1-2 weeks, you can expect some minor discomfort. This is because your teeth are shifting, which naturally causes some soreness. The good news is that you can take an over-the-counter pain reliever to alleviate discomfort. Also, it should not last longer than a few days.