What Is a Dental Crown and When Do You Need One?

What is a dental crown?

A crown covers the entire visible portion of a tooth above the gum line. Once cemented in place, it becomes the new outer surface of the tooth, protecting the natural structure underneath. Crowns are made from several materials — tooth-colored porcelain or ceramic, zirconia, metal alloys, or combinations — each with trade-offs in strength, durability, and appearance. Your dentist will recommend a material based on where the tooth is and how much chewing force it bears.

When is a crown necessary instead of a filling?

A filling restores a portion of a tooth by filling a cavity or replacing a small damaged area. A crown is used when the damage is extensive enough that a filling would leave the remaining tooth structure too fragile or too small to hold a restoration reliably. Common situations that call for a crown include:

• A large or recurrent cavity. When more than roughly half the tooth surface is affected by decay, a filling is unlikely to hold well. ADA evidence-based guidelines support restorative treatment proportionate to the size and depth of carious lesions 1Ref 1Dhar V, Pilcher L, Fontana M, González-Cabezas C, Keels MA, Mascarenhas AK, Nascimento M, Platt JA, Sabino GJ, Slayton R, Tinanoff N, Young DA, Zero DT, Pahlke S, Urquhart O, O'Brien KK, Carrasco-Labra A (2023).Evidence-based clinical practice guideline on restorative treatments for caries lesions: A report from the American Dental Association.Restorative treatment should be proportionate to cavity size and depth; extensive decay supports crown rather than filling.
• A cracked tooth. A crown holds a cracked tooth together, preventing the crack from propagating and the tooth from splitting under biting force.
• After root canal treatment. Root canal treatment removes the pulp and can leave a back tooth more brittle and prone to fracture. Placing a crown over a root canal-treated molar significantly reduces the risk of tooth loss.
• A broken or severely worn tooth. Teeth fractured by trauma or worn down by grinding (bruxism) often need a crown to restore function.
• A large, failing filling. When an old filling breaks down or recurrent decay develops around it and leaves too little natural tooth, a crown may be the better long-term solution.
• A dental implant. The visible part of an implant is a crown attached to the implant post.

What does getting a crown involve?

A crown typically takes two appointments:

1. First appointment. The dentist numbs the tooth and reshapes it by removing a thin, uniform layer of enamel from all surfaces to make room for the crown. An impression (or digital scan) is taken, and a temporary crown is placed while the permanent one is made in a lab. Same-day crowns milled from a digital scan are now available at some practices. 2. Second appointment. The temporary crown is removed, the fit and bite are checked, and the permanent crown is cemented in place.

The tooth and gum area will likely feel tender for a few days after each appointment. Bite sensitivity that persists longer should be reported to your dentist.

How long do crowns last?

With good oral hygiene and regular dental visits, crowns commonly last ten to fifteen years or longer. The junction between the crown and the natural tooth (the margin) is where decay can recur if plaque accumulates, so brushing carefully at the gumline and flossing around the crown are important. Grinding or clenching shortens crown lifespan and is a reason dentists often recommend a nightguard.

For comparison, dental implants — which use a crown on top — have high long-term survival rates when placed in appropriate patients and maintained properly 2Ref 2Moraschini V, Poubel LA, Ferreira VF, Barboza ES (2015).Evaluation of survival and success rates of dental implants reported in longitudinal studies with a follow-up period of at least 10 years: a systematic review.Dental implants (which use crowns) have high long-term survival rates when maintained properly.

Is there an alternative to a crown?

Sometimes. An inlay or onlay (a partial crown that covers one or more cusps rather than the whole tooth) is an option when a filling is insufficient but the tooth does not need full coverage. For very early decay, non-restorative options such as fluoride varnish or silver diamine fluoride can arrest a lesion before a filling or crown is needed 3Ref 3Slayton RL, Urquhart O, Araujo MWB, Fontana M, Guzmán-Armstrong S, Nascimento MM, Nový BB, Tinanoff N, Weyant RJ, Wolff MS, Young DA, Zero DT, Tampi MP, Pilcher L, Banfield L, Carrasco-Labra A (2018).Evidence-based clinical practice guideline on nonrestorative treatments for carious lesions: A report from the American Dental Association.Non-restorative treatments can arrest early lesions before crowns or fillings are needed. Your dentist will discuss which approach is most appropriate given your specific situation.