Inlays and Onlays

Inlays and Onlays are a form of indirect restoration, which means they are made outside of the mouth as a single, solid piece that fits the specific size and shape of the cavity.

Inlays and Onlays

What are Inlay and Onlay?

Inlays are moulded and fitted into the chewing surface of a tooth that has been damaged through decay or injury. They are created using an imprint of the affected areas that are sent to a lab for manufacturing. An inlay will fit perfectly into the hollow of the tooth, but they do not affect the cusps. When the dentist takes the impression, they also attempt to best match the colour of the tooth as closely as possible. This way when they are placed in the mouth they are not noticeable. The material used for an inlay can be either porcelain or a composite material that is stronger and more durable than traditional fillings. This makes inlays generally more expensive, but also longer lasting. A dentist chooses this option when a filling will not properly strengthen the surrounding tooth and the cavity requires stronger materials to fortify the tooth.

Onlays are used for decay and damage to the cusps of a tooth as well as the biting surface. A dentist will choose an onlay when a cavity is too big to fill with standard amalgam fillings, or that the tooth could crack due to weakness. An onlay will shore up the strength of the tooth along with protecting the decaying area. Unlike an inlay, this area can include the cusps as well as the space in between. The dentist similarly prepares the tooth for a filling, by drilling out the cavity and cleaning up the area after placing a numbing anesthetic in the mouth. A temporary onlay is then placed over the cavity, and the impression is sent for a permanent onlay to be manufactured. It is then placed in the mouth when it arrives. With an onlay, the tooth structure is preserved, whereas with a crown some filing and even removal of cusps may be necessary.

All on 4 London Examination

Step One :

Consultation, X-rays, diagnosis and treatment plans


All on 4 London

Step Two :

Impression taking and tooth preparation

All on 4 London review

Step Three : Fit & Cementation

Inlay or Onlay fit

The process of preparation and cementation of an inlay or onlay is usually carried out over two appointments, with the preparation being carried out during the first appointment and cementation during the second. After the tooth has been prepared at the first visit a putty and wash impression should be taken of the prepared tooth to be sent to the laboratory for fabrication of the indirect restoration. Also, a provisional restoration is made, to protect the tooth from sensitivity, loss of vitality, bacterial contamination. To prevent over-eruption of the prepared tooth, and also maintain dental aesthetics for the time being.

Inlays and Onlays are cemented in the mouth using adhesive resin luting cement. These materials are placed in the inlay/onlay and placed onto the prepared tooth. Once the onlay/inlay is seated, the viscosity of the adhesive resin luting cement decreases. This makes placing the inlay/onlay easier and reduces the chances of breakage.

How Long Do Inlays and Onlays Last?

One of the main benefits of inlays and onlays is how durable and long-lasting they can be. You can expect an inlay to last anywhere between 5 and 30 years.

Inlays and onlays have some similarities but serve specific, unique purposes. Many dentists consider them to be great alternatives to fillings, crowns, and other dental restoration options. 


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