Indications for dental crowns - Replace failed existing crowns - Restore badly broken down, worn, or fractured teeth - Improve aesthetics of unsightly teeth - Maintain structural stability of extensively restored teeth - Restore the visible portion of a dental implant

Restoration of endodontically treated teeth - No strong evidence to show that crowns are better than other restorations for root-filled teeth - Dentists should use clinical experience and patient preferences to decide on crown use - Crowns justified when access cavity exceeds one third of occlusal surface or when walls and marginal ridges are missing

3/4 and 7/8 crowns - Hybrid between onlay and full crown - Covers three out of four walls of the tooth - Often fabricated in gold - Grooves or boxes added for increased retention - Technically difficult and poor patient acceptability due to metal showing through

Full metal crowns - Cast entirely in a metal alloy - Alloys categorised as high-noble, noble, or base metal - Gold alloys commonly used for casting crowns - Palladium-based alloys introduced as a cheaper alternative to gold - Base-metal alloys also used

Types of gold alloys - Gold alloys used in casting crowns contain metals like copper, platinum, palladium, zinc, indium, and nickel - Type III and IV alloys commonly used for full crowns - Gold crowns indicated for posterior teeth due to aesthetic reasons - Durable and require minimal tooth preparation - Have good dimensional accuracy and similar wear properties to enamel