What are Inlays & Onlays?

Dental inlays and onlays are a medium between dental crowns and fillings. The two main types of inlays and onlays are made from resin or porcelain. Occasionally they can be made from gold. Dental inlays and onlays are restorations typically used when your teeth are not sufficiently damaged enough to need a crown, but are too damaged to be successfully treated using a filling. They are most commonly used on back teeth that can crack or fracture, or if you are suffering with mild to moderate decay.

 This type of dental product is bonded into place around the cusps (the little mountain peaks on top of the back teeth). Onlays are used to cover one cusp or more, whereas dental inlays tend to be used more as a filling between the cusps.

Typical treatment length

12 – 18 months

What is the process?


Prior to treatment your clinician will assess your tooth/teeth which may include taking an X-ray. If you have any decay then this will be treated before providing the inlay/onlay.


  • Colour matched your teeth and often chosen to replace metal fillings
  • Potential for them to last for decades with good oral hygiene and regular dental checkups
  • Preparation of the tooth/teeth is far less invasive than with a crown
  • It is easier to establish an ideal biting surface shape, to further protect the remaining tooth structure, than with conventional filling materials
  • Your new inlay/onlay is ready to be bitten on immediately


  • Smoking and drinking alcohol can affect the outcome
  • There are no lifetime guarantees
  • It may require two separate visits whereas other filling options can be completed in one visit
  • They are a costly procedure and will incur the maximum NHS charge as a complex treatment
  • They are made using incredibly strong material which may cause adverse wear on your other teeth


Your clinician may numb the area with local anaesthetic before preparing your tooth, an impression will then be taken and this will be sent to the laboratory where your dental inlay/onlay will be carefully constructed. You will have a temporary restoration placed over your tooth until your inlays/ onlays/ are ready which may take up to two weeks. At the fitting appointment your dentist may again numb the area around the tooth before removing the temporary restoration and your new dental inlay/onlay will be bonded into place.


Your final restoration will be checked to ensure you can bite down properly and that your teeth meet in a comfortable position.