What Are Porcelain Onlays And When Are They Used?

Porcelain onlays are a conservative long-lasting solutions used to restore damaged teeth.

A dental onlay is a restoration technique that is used to restore damaged teeth. The teeth may be damaged from chipping, cracking or caries/decay. It is more conservative than a crown as less tooth structure is removed in the preparation of the tooth.  It is an indirect restoration as it is fabricated in a laboratory by a ceramist and cemented onto the tooth by the dentist.

An Onlay is preferred where the amount of damage to a tooth is too large for a regular filling or where there is a crack in a tooth that requires protection.  Onlays are more conservative as not as much tooth structure would be removed compared to a crown, but it continues to cover the entire bite surface of the tooth offering greater protection to the tooth.

Are there other Types of Dental Onlays?

Dental onlays can be made from many different types of dental materials such as gold, resin and porcelain.  These material differ in appearance and durability. The material of choice will depend on the desired cosmetics, the cost and the material properties required for a particular location in the mouth.

Gold as a material for a dental onlay offers the best durability and the greatest longevity.  But if a natural white appearance is desired then porcelain onlay or resin onlay are the alternative option.  Porcelain is well bonded to the tooth structure and merges into the enamel for a highly cosmetic end result.

Resin Onlays are completed for cost saving purposes, they look great but will have a shorter life due to the limited strength of the resin material.

Treatment Procedure for a Porcelain Onlay:

  1. The tooth is numbed so there will be no pain.
  2. The tooth is prepared for the Onlay – it is important there is a full periphery of enamel available, the top of the tooth is reduced only by the amount required for sufficient porcelain thickness and any old restorations or decay is removed.
  3. A replica of this preparation is sent to the laboratory and the porcelain onlay is made by the ceramist and returned to our dentist.
  4. The porcelain onlay is cemented to the tooth with a bonding procedure  – the type of bonding procedure is critical to the success of the Onlay and gives the porcelain strength and durability.

When is a Porcelain Onlay used?

Extensive caries and broken tooth structure.

When the amount of tooth structure lost due to chipping or due to caries is large, a regular filling will have a shorter life.  A porcelain onlay will offer greater longevity and help protect the tooth from further damage.

Cracked teeth.

When a tooth is cracked, the fracture line has the potential to continue to extend deep into the tooth and the root.  When this fracture is extensive the tooth may required removal and cannot be saved. A porcelain onlay can help to protect the tooth by spreading the load across a more even surface of chewing and help to stop the fracture line travelling deeper into the tooth.  The fracture line may continue to grow, but it is hoped the onlay will slow down the movement and allow you to keep your tooth for longer.

What are the Advantages of a Porcelain Onlay?

  1. Less tooth structure is removed in the preparation of the onlay.  They are a more conservative option compared to a crown.
  2. Onlays can be both durable and aesthetic, so they look great and they last longer than a regular resin filling.
  3.  Porcelain onlays fit like a glove when cemented well so they are unlikely to decay easily at the margins where the porcelain meets the enamel.
  4. Brushing and flossing the onlay is smooth and easy,  protecting the onlay from deterioration.


If you would like more information regarding a porcelain onlay and other restorative options for your teeth, don’t hesitate to book in for a chat with our lovely dentist Dr Barbara.


We are an Accredited Dental Practice and a Member of the Australian Dental Association

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