Dental crowns and bridges are customised prosthetic restorations used to replace or restore damaged or missing teeth. Crowns, also known as "caps", are permanently cemented restorations placed over the surface of natural teeth or dental implants. Bridges are used to fill the gaps left by  extracted teeth or teeth missing for another reason and are supported in place by the natural teeth on either side of the gap. Both types of restoration are considered permanent, as they do not need to be removed from the mouth. Choosing a crown or a bridge to restore a lost tooth achieves both better function and a natural appearance, as well as dental hygiene.