With over 8 million cases and 20 years in use Invisalign is safe to use. Invisalign treatment is not painless; however, studies show it’s 90% less painful than traditional braces. Most describe it as “firm or snug” the first 2 days and then it becomes more comfortable after. This is especially true with the new “Smarttrack” material. While you use the aligners, you cannot eat and only drink water. Any other liquid containing sugar can underneath the aligners and cause cavities.