Crowns are used most commonly to entirely cover or "cap" a damaged tooth. They are made by a technician and bonded by the dentist in the surgery. They can be made of porcelain, porcelain fused to metal, zirconia and even gold. Your dentist may recommend a crown to:
Replace a large filling when there isn't enough tooth remaining
Protect a weak tooth from fracturing
Restore a fractured tooth
Cover a discoloured or poorly shaped tooth
Cover a tooth that has had root canal treatment