What is an Onlay: 6 Benefits of Dental Onlays

Dental Onlays

Last Updated on: 21st May 2024, 08:37 am

Have you ever wondered what is an onlay? Have you experienced a fractured tooth or a cavity before? If that’s the case, you must be familiar with dental restorations. There are several types available, with fillings and crowns being the most well-known. However, another common type is dental inlays.

What is a Dental Inlay?


Dental inlays are a form of indirect restorations, meaning they are crafted outside the mouth using a plaster model of the damaged area, such as a cracked tooth, that requires reconstruction. Once created, these inlays are then cemented onto the affected tooth to rebuild the lost dental structure. This procedure is typically carried out on posterior teeth and is suitable for repairing teeth with mild to moderate decay, as well as those that have experienced cracks or fractures.

There are different types, depending on the degree of tooth involvement. Currently, the most used are:

    • Inlays: They do not involve the cusps of the teeth, but rather are limited to the central part.
    • Onlays: They rebuild one or more cusps of the tooth.

What is an Onlay?

They are used to treat extensive caries involving one or more cusps of the premolars or molars. These can be considered the middle option between traditional fillings and full crowns.

Onlays replace less of the healthy tooth than a full crown. Therefore, they are a more conservative treatment option, where the carving seeks to preserve the periphery of the tooth as much as possible, limiting it to the masticatory surface.

What Materials are used in the Inlays?

Inlays procedure

The inlays can be made of various materials:

    1. Several years ago it was the most used material for inlays, faced with masticatory forces, its shape can be modified and adapted to the tooth, protecting the remaining dental structure from suffering fractures. Currently, metals have fallen into disuse, due to the appearance of natural tooth-colored materials, such as ceramic and resin. However, poor aesthetics aside, gold is still the best option, which is why many dentists prefer it in cases where inlays fracture frequently or where aesthetics are not as important, such as molars.
    2. Ceramics: They are highly aesthetic inlays, have greater shape stability than resins, and are not susceptible to staining. They can be made conventionally or using CAD-CAM technology (computerized design and 3D printing), so very precise shapes can be obtained. However, they are more fragile than gold inlays, and due to their greater rigidity, they increase the risk of dental fracture.
    3. Composite resin: They are inlays made of the same resin material used in dental fillings, but they have greater shape stability, greater resistance, and better adaptation. They are tooth-colored but are not stain-resistant. In addition, they are more fragile than inlays made of ceramic or gold.

When are Dental Inlays Indicated?

different ceramic inlays and onlays

Onlays are considered the appropriate treatment in cases of tooth damage from decay or fracture where a filling would not suffice, but a crown would be a very aggressive option. They are usually indicated in large cavities that require a coating of the cusps, such as teeth that have received endodontic treatment but are not seriously destroyed. They are also a good option for patients with bruxism.

What is the Procedure for an Onlay?

The procedure for placing an inlay generally requires two appointments:

    • After removing the decay or defective restoration, the dentist carves and prepares the tooth to receive the only. Subsequently, an impression is taken, from which a plaster model will be obtained to allow the inlay to be created in a laboratory. Meanwhile, the tooth is protected with a temporary inlay made in the office.
    • The temporary inlay is removed, the cavity is cleaned, and the inlay is cemented. After checking the bite, the inlay is polished to match the natural teeth.

What are the Benefits of Onlays?

what is an onlay
what is an onlay
    1. Greater precision: As they are made in the laboratory, it is easier to make restorations that adapt precisely to the tooth since factors such as humidity, lighting, and material characteristics are better controlled.
    2. Promotes the preservation of the dental structure: It requires minimal removal of the healthy tooth surface, as compared to dental crowns.
    3. Highly aesthetic: When performed with materials such as ceramic or resin, the color can be identical to the natural tooth such that they are practically invisible.
    4. Stable form: Unlike conventional resin fillings, dental inlays do not expand or contract in response to changes in temperature inside the mouth. This size change happens with composite fillings and can cause teeth to become weak or fractured, especially teeth with root canals.
    5. Reduces the risk of future cavities: By improving adaptation, leaks are reduced along with the possibility of generating spaces where cavities can appear.
    6. Longer duration: Studies have shown that performing more conservative procedures, such as dental onlays, can prolong the duration of the result.

How much does it Cost to do an Onlay?

The cost of an onlay is between $650 and $1,200. This value may vary, depending on the material used, the size of the inlay, the professional in charge of the procedure, the quality of the laboratory, and the location of the office.


Daily dental hygiene habits, such as proper brushing after meals and the use of supplements such as dental floss as well as regular visits to the dentist are all that are needed to keep dental inlays in good condition and prevent the spread of decay from between the tooth and the adhering material.

Remember that the dentist is the right person to advise you on the habits you must maintain, so do not hesitate to visit your dentist’s office frequently.

Frequently Asked Questions

The main difference between these two treatments is that embedding achieves better aesthetics and more effectively restores the normal chewing function. In addition, it is a technique that does not require carving the entire surface of the tooth, which allows the healthy structure of the dental piece to be preserved.

The exact duration of a dental inlay cannot be accurately determined, as it depends upon several factors. However, they generally have a useful life ranging from 5 to 25 years. The presence of caries and fractures are the main factors that can reduce the durability of inlays.

These are a technique indicated for people who have damage to their teeth, but who have not yet developed serious cavities or other more severe disorders. It is recommended to undergo this treatment in the following cases: when you have a cavity or fracture that is too large to resort to dental reconstruction.

Contact Us

If you have any questions about dental conditions, you can contact us at Channel Islands Family Dental as well as our page on Facebook. We look forward to your visit and we will make a timely diagnosis. Our dentists in  Oxnard, Santa Paula, Ventura, Newbury Park, and  Port Hueneme will be able to guide you toward the best treatment to take care of your health and give you back your best smile.


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  3. Sugue, M. (Jan 5, 2020). Dental inlays & onlays – materials, procedure & costs. NewMouth; Dentistry Brands LLC. Available from:https://www.newmouth.com/dentistry/restorative/inlays-onlays/
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