Bridges are fitted permanent restorations which replace missing teeth. The replacement teeth are supported by existing natural teeth or implants. There are a number of different types of bridges but, an example of a traditional or conventional bridge design is a replacement tooth (called a pontic) supported by a teeth with crowns (abutment) at either end of the gap.
A resin retained bridge or enamel bonded bridge is an appliance which uses a framework of metal or porcelain. The replacement tooth is attached to this framework and the appliance is bonded to the supporting natural teeth. While this technique is very conservative of natural tooth structure, it is only suitable for some cases where the biting forces are favourable.