Yes, sometimes even the pros get it wrong. Occasionally dentists need to redo their impressions too. If you got your impressions done at the dentist, and they were rejected, please go back to your dentist. They should redo them free of charge. Contact our customer service first to make sure you understand what was wrong with the impression, so your next one is perfect. Most problems are that the impression wasn't deep enough (especially by the back molars) and/or that the gumline wasn't sufficient on all teeth.