Crowns should last approximately 10 years if maintained well and not abused (i.e. biting very hard things). Therefore, it is important to take good care of them so that they can last as long as possible. Refer to this question for tips on how to care for your dental crowns and bridges.
Like everything, they will be subject to some wear and tear and will require replacement eventually. Here are some cases when it will be necessary to replace the dental crowns with new ones:
- Cracked or broken crown
- Excessive wear resulting in holes (perforation) found on the crown
- Recurrent tooth decay underneath the crown
- Gum recession resulting in the edge of the crown being visible (eg. dark line)