(Artificial) dental crowns and bridges are so-called fixed dentures – in contrast to partial and full dentures that are removable.
A dental crown is the “covering” of an existing but (severely) damaged tooth, while a dental bridge is when a lost tooth is completely replaced.
Nowadays, however, a missing tooth is usually replaced with a dental implant, as this has the great advantage that no neighboring teeth have to be ground and included in the restoration of the tooth gap (as is the case with a bridge).
Decisive for the decision whether a crown or a bridge, resp. an implant is inserted, is the question whether only the (natural) tooth crown or also the tooth root, resp. the entire tooth is damaged and the corresponding tooth has to be removed.