What are onlays?

When a tooth has been repaired with a large filling, the remaining tooth structure becomes weak and liable to break. Often the first break is swiftly followed by subsequent breaks as the structure is further weakened. In some situations, these breaks can be repaired. However, if a break occurs close to the gum, it may render the tooth unfixable, and it would need to be removed.

A filling is unable to prevent further breakages as it cannot hold the tooth together. The alternative is an onlay, which can be designed to protect fragile remaining portions of tooth. Studies have shown that 10 years after placement, 25% of large fillings are lost but only 10% of crowns have failed. Our onlays are made of tooth coloured porcelain. Porcelain is a ceramic material that has very similar optical properties to tooth, which allows it to be used to create incredibly natural appearing repairs.

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Our results

Let us help you to keep your smile looking beautiful. Have a look at some of the smiles our experienced dentists have changed already.

Before treatment
After treatment

A tooth repaired with a porcelain onlay by our dentist Dr. Andrew Paterson


  1. Book a new patient preventative dental health check.
  2. Let us assess the condition of your teeth.
  3. Let us provide seamless repairs to your teeth.

Frequently Asked Questions

  • What is an onlay?

    An onlay is a cap or hat placed over the top of a tooth to protect its structure or improve its appearance. A small part of tooth structure is removed to create space for the onlay so the tooth is normally not made any larger.

  • What is an onlay made of?

    Onlays can be made from metals such as gold or tooth-coloured materials such as porcelain. Porcelain is a ceramic material that has very similar optical properties to tooth, which allows it to be used to create incredibly natural appearing onlays.

    Almost all the onlays we make are tooth coloured. Most are made of a lithium disilicate crystal porcelain that looks very similar to tooth.

  • How long does an onlay last?

    The lifespan of an onlay varies depending on material, whether you grind your teeth, and how clean it is kept. Research suggests 76% are still in place at 16 years.

  • How much damage does having an onlay do to my teeth?

    In almost all cases, placement of an onlay requires removal of a certain portion of your tooth’s structure. The amount of structure removed depends on the material used, with more aesthetic materials, such as porcelain, requiring removal of more structure.

    Research suggests that an onlay requires removal of 33% of your tooth’s crown. The implication of this is that this removal can harm the nerve of the tooth. There is a 1% chance your tooth will require root canal treatment in the subsequent 10 years.

  • What is the difference between a crown and an onlay?

    A conventional crown covers the entire surface of your tooth above the gum level. This creates the best aesthetics however requires removal of 69% of your tooth’s structure and creates the 14% risk of damage to the nerve of your tooth. Historically this has been the conventional method of protecting a tooth.

    An onlay is a contemporary technique to remove less of your tooth structure. The main advantages are far less removal of tooth structure (33% compared to 69%) and far less chance of damage to the nerve of your tooth (1% compared to 14%). The only disadvantage is very slightly inferior aesthetics.

    Onlays are a new technique in dentistry which has only become possible due to advances in our ability to bond to tooth enamel, which is a notoriously difficult material to stick to. This is a revolution in dentistry.

    In most situations where your tooth still has a nerve, we recommend onlays.

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We would love to invite you to our practice for aesthetic treatments, advanced treatments, or the highest quality routine family dentistry.

27 Western Terrace,
Falmouth, TR11 4QL

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