Teeth that are slightly chipped or discolored can sometimes be repaired by dental bonding, or a related method. But when a tooth is lacking much of its structure or is entirely missing, then a crown or bridge may be the restoration of choice.
A crown is simply a tooth-shaped covering that fits over a single damaged or discolored tooth. It covers the whole surface above the gum line. When they are placed they look just like your natural teeth.
If a tooth is completely missing, the crown has nothing to attach to directly. But with bridgework, it gets a little help from its neighbors. A bridge requires that the healthy teeth on either side of the missing one be prepared for crowning. In some cases when more than one tooth is missing, a larger bridge can be constructed.