Crowns are caps on teeth that are sometimes needed to be placed to strengthen the tooth.
They can last a lot longer than fillings and are the appropriate treatment of choice when a large amount of tooth structure is missing and there is need for additional reinforcement.
Bridges can be done to replace missing teeth by putting crowns on two adjacent teeth.
Veneers are done on anterior teeth to improve their appearance. They are more conservative than crowns and preserve more tooth structure.
They cannot be done when additional reinforcement is required of if the tooth is structurally compromised.