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Onlays

Onlays are dental restorations for posterior teeth.

They are more durable than fillings and protect the teeth on which they are placed.

They are also a great alternative to crowns.

They protect the teeth they are placed on without having to remove as much tooth structure, as is the case with crowns.

In the past, onlays were made of gold, but when the price of gold became too high, onlays were no longer used.

In the last decade, dentistry has shifted its focus to tooth tissue preservation.

The purpose of our restorations is to strengthen damaged teeth without removing more tooth structure than has already been lost.

The evolution of the materials available to us, as well as changes in bonding techniques, have allowed us to reuse onlays with great success, creating restorations that are highly aesthetic and functional, yet very conservative for the teeth on which they are placed.

An onlay requires two visits to the clinic.

In the first, the old filling and any decay are removed from the tooth, the cavity is shaped appropriately and then the impression is taken, which in our practice is done digitally.

At the second appointment, the onlay is cemented in place with special resin cement,

BEFORE and AFTER

Click the arrow to the right for more photos of each case
After

We bonded to the teeth, ceramic onlays that filled in the missing part of the tooth without grinding it further.

If we had opted for the crowns, the teeth would have had to be ground down much more and the remaining tooth substance would have been minimal.

The restoration replaces both the occlusal part of the tooth as well as the buccal and this is why it is also called vonlay

Before

Onlays can be used to fill in the missing part of the tooth without removing more tooth structure.

In this case, the teeth had been significantly worn down by erosion and much of the tooth substance had been lost.

After

Ceramic onlays were placed on the posterior teeth on both sides of the upper jaw.

The teeth regained their correct shape and our patient’s smile regained the confidence it had lost.

Before

The smile of the patient in the photo was very hesitant prior to treatment as the back teeth had significant erosion and looked as if they were missing.

The patient did not want crowns on his teeth as they would have had to be ground down further.

Ceramic vonlays
After

Composite onlays, bonded to the remaining tooth structure, restored the teeth to their original shape while preserving the tooth structure.

Before

The molars in the photo had undergone endodontic treatment (root canal) and needed to be restored.

If we chose to restore them with crowns, we would also have to grind down the little tooth structure that was left.

Then the tooth would definitely need a post and core.

Composite resin onlays
After

Ceramic onlays protected the teeth, gave them a normal anatomy and did not remove any additional tooth substance.

Here, the ceramic onlays in the posterior teeth were part of a comprehensive treatment plan.

Before

The patient with tooth erosion had lost a large amount of tooth structure.

The teeth were sensitive, old fillings protruded from the chewing surface of the teeth and some teeth had decay.

Ceramic onlays for a patient with teeth erosion
Questions
  1. Which teeth do the onlays go into?

    For natural posterior teeth that are missing a lot of tooth substance and where a filling does not have a good prognosis.

    Consider an onlay if you:

    • have a large filling that is constantly coming out of the tooth
    • are considering a crown
    • need to fill a tooth that is decayed
    • have a large chipped tooth in the back of your mouth.

  2. Why is an onlay better than a filling?

    To make a large filling, we have to work in stages, slowly polymerising the material we use until we have filled the tooth cavity.

    This process can lead to micro-gaps between the tooth and the filling as the material polymerises and contracts, and during polymerisation the composite resin can cause small cracks in the fine tooth substance left in a tooth, which can later lead to tooth fracture.

    The onlay has an advantage over a simple filling because

    • It is made of materials with better properties
    • It has high aesthetics
    • It has a higher durability in time
    • It helps to protect the tooth from fractures

  3. Why is an onlay better than a crown?

    Until recently, teeth that needed large fillings were often crowned.

    However, a crown requires the removal of  an amount of tooth structure, which weakens the tooth.

    Some teeth that used to require crowns can now be restored with resin or porcelain onlays.

  4. Do all fillings need to be replaced with an onlay?

    No. We prefer onlays if your tooth is missing a large amount of tooth structure.

    Onlays are also better if you have a fractured cusp or if your tooth has undergone endodontic treatment.

  5. Is a crown better that an onlay?

    If your tooth already has a crown, you cannot have an onlay placed.

    Onlays are only placed on natural teeth.

    If there is a lot of tooth substance lost, a crown may be the only solution.

  6. What materials are the onlays made of?

    Onlays are made of porcelain or polymer materials that match the colour of the tooth.

    The choice of material depends on

    • the size of the restoration,
    • the position of the tooth in the dental arch
    • and the presence or absence of bruxism
    • the patient’s finances

  7. Are there any disadvantages to onlays?

    The disadvantages of the onlay are that

    • it takes two appointments
    • it is a more expensive than a filling

Videos
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Onlays