Crowns and bridges can be made from gold, (PFM) porcelain fused to metal and all-porcelain.
Porcelain is usually always used for the front teeth but may now be used for the back teeth since the newer generations of porcelain are essentially as strong as gold. Some porcelain crowns have gold on the inner portion of the crown. Porcelain crowns can appear very natural and allow for the replacement of the front teeth without people being aware of the change.
A bridge allows the dentist to replace lost teeth without the use of a denture or implant. Basically a bridge is a crown on each side of the missing tooth which are used to hold in the new false tooth.