These are braces that are clear or opaque. They match the tooth color very well. Almost all of them are made from a ceramic material, aluminium oxide. When the ceramic ones were invented in 1987, almost everyone stopped using the plastic and lingual braces. They work the same as metal braces, but produce a little more friction and can prolong the treatment time. You have to be very close to someone to be able to see them, and that is why they are so popular with adult patients.