When a tooth is lost due to decay, fracture, or trauma, a bridge is one way to replace that missing tooth. Your dentist will prepare the teeth on either side of the space for crowns.  An impression of all your teeth is sent to the dental labratory along with photos to get the color match.  The lab then makes a restoration which spans the space and attaches to the adjacent teeth. The restoration resembles a bridge, hence the name.  The bridge is then custom fit and permanently cemented in place.