Your Guide to Inlays and Onlays
Find out how inlays and onlays work. They sit between a filling and a crown. See what treatment involves and whether one might be right for you.
What are inlays and onlays?
An inlay or onlay is a made-to-measure repair for a damaged back tooth. It sits inside or over the tooth. A dental laboratory makes it from porcelain, ceramic or gold. It is then stuck (bonded) firmly to your tooth.
- An inlay fits between the bumps (cusps) of the tooth. It fills the middle of the biting surface.
- An onlay covers one or more of the bumps. It covers more of the tooth than an inlay, but less than a full crown.
They are sometimes called "indirect fillings". This is because they are made outside your mouth and then fitted.
When might I need an inlay or onlay?
You may be offered an inlay or onlay when:
- A tooth is too damaged for a simple filling but does not need a full crown
- A large filling has broken down and needs replacing
- The biting surface of a tooth has cracked or broken
- A hard-working back tooth needs something stronger than a filling placed straight into the tooth
Inlays and onlays compared with fillings and crowns
Inlays and onlays sit between fillings and full crowns. This is about how much of the tooth they involve:
- Filling — placed straight into the tooth in one visit. It is the quickest and lowest cost. It is best for small to medium holes.
- Inlay or onlay — made in a laboratory, over two visits. It fits more precisely. It is better for larger repairs in back teeth. It lasts better than large fillings. It keeps more of your tooth than a crown.
- Crown — covers the whole tooth. You need one when too little healthy tooth is left for an inlay or onlay.
What happens during treatment?
An inlay or onlay takes two visits.
First visit:
- Your tooth is numbed with an injection (local anaesthetic)
- Decay or old filling is removed, and the tooth is shaped to take the inlay or onlay
- A mould (impression) or digital scan is taken and sent to the laboratory
- A temporary filling protects the tooth while the inlay or onlay is made. This usually takes 1–2 weeks.
Second visit:
- The temporary filling is removed
- The inlay or onlay is checked for fit and bite. Then it is fixed to the tooth for good.
Risks and possible complications
Common:
- The tooth feels sensitive for a few days to weeks after fitting
- Your bite sometimes needs a small adjustment
Uncommon:
- The tooth may need root canal treatment if the nerve (pulp) is affected. Your dental team will talk about this risk before treatment if it applies to you.
- The inlay or onlay comes unstuck (debonding)
With good cleaning and regular check-ups, porcelain inlays and onlays usually last 10–20 years.
Questions to ask your dental team
- Why is an inlay or onlay better than a large filling for my tooth?
- Which material do you advise: porcelain, ceramic or gold?
- Could this tooth need a crown one day?
- How should I look after it so it lasts as long as possible?
This leaflet is for general information only and does not replace professional dental advice. It is intended to support — not replace — the discussion with your dental team about your individual options, risks, and treatment plan. Treatment outcomes vary between patients depending on individual circumstances. Your dental team will confirm exact fees and what is suitable for your specific circumstances before you agree to any treatment.
Sources
- Crowns, Fixed Bridges and Dental Implants: Guidelines. British Society for Restorative Dentistry, 2013.
- Dental treatments. NHS website (nhs.uk), reviewed July 2026.
Links checked 18 October 2026.
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Related leaflets
For clinicians: Inlay / Onlay notes template.
Learn more about dental documentation on our blog or see Nosht pricing.