How can a patient find their dental records if they've forgotten who their last dentist was?

You can contact your dentist's office and request a copy of your records, or you can go in person to request them. Your new dentist can also request a copy of them, but you will need to sign a release form giving your former dentist permission to release the records to your new dentist. If that's the way you go, your new dentist will have you sign the release forms, then they will send it to the former dentist for you.