Esthetics is one of the main concerns for adults seeking orthodontic treatment. Braces themselves have become more esthetic over the last 20 years, becoming smaller and less obvious with clear plastic or ceramic braces more commonly used. It is also possible to have the brackets placed behind the teeth (lingual braces). These are virtually invisible, but are more irritable to the tongue. Modern wires are also less noticeable than earlier ones. A type of tooth-colored orthodontic wire is currently in an experimental stage. With the advances in technology, teeth can now be straightened with a series of clear, plastic, removable aligners without metal wires or brackets. Teeth will move - little by little, week by week - by a series of aligners until they have straightened to the final position the orthodontist has prescribed. These sequential plastic aligners (Invisalign®) can align teeth, but they cannot correct significant bite discrepancies.