Conventional bridges require the tooth to be prepared all around to create space (just like with a crown). They are the more retentive type of bridge but at a loss of natural tooth tissue.
Modern practice dictates that we try to preserve as much natural tooth tissue as possible. If it is feasible it may be decided that the more conservative Resin Retained Bridges can be provided. This does not require any preparation, but instead relies on the strong bond between the wing of the bridge and the tooth it is bonded to.
Their longevity is generally 7 years, however, if they are looked after and the correct advice is being followed, they can last for a lot longer. If they de-bond, the benefit is that they may be treated and cemented back on the same day.