Does This Tooth Need an Onlay or a Crown?
An onlay and a crown cover different amounts of a tooth. Understand the choice and ask which findings make a restoration suitable for your tooth.
The old filling is large, and the dentist suggests covering part or all of the tooth. An onlay replaces missing structure and extends over weakened biting surfaces. A crown fits over a prepared tooth. Both can be ways to restore a damaged tooth, but the amount and shape of the coverage differ. An inlay, another term you may hear, generally sits within the tooth rather than covering its biting cusps.[1][2]
Start with what is left of the tooth
Ask the dentist to show you which areas are sound and which need protection. 'Why is a filling no longer suitable?' and 'Which parts would the onlay cover?' are more useful questions than choosing from a photograph of the finished restorations. The examination may include the condition of the pulp, the gums and imaging where needed before an indirect restoration is planned.[1]
If a crown is recommended, ask why partial coverage would not be suitable here. If an onlay is recommended, ask what makes the remaining tooth suitable to keep. These questions are not a test the dentist has to pass with one slogan. You are looking for the finding that explains the recommendation for this tooth.
Coverage and material are separate choices
An onlay is a type of restoration, not the name of a single material. Options can include ceramic, resin-based materials and metal alloys. Discuss the proposed material as well as the extent of the restoration. The ADA identifies location, size, appearance, expected durability and out-of-pocket cost as factors in choosing restorative materials.[1][3]
For example, say whether the tooth is visible when you smile and ask how your bite affects the choice. If two options are reasonable, request an estimate for each that includes the full planned treatment. A smaller restoration is not automatically the right one, and a more extensive restoration is not automatically better because it covers more.
Understand the next step before preparation
Ask whether the restoration will be made at the visit or in a laboratory, whether a temporary is needed, and what the team would do if removing the old filling reveals more damage. That last question helps you understand where the plan might change. If you need time or another opinion, ask how urgently the tooth needs protection and what to avoid while deciding.