Dental crowns and onlays

Options for restoring teeth

There is a limit to the strength and therefore the longevity of composite and amalgam fillings for replacing lost fillings, fixing broken teeth and restoring rotten teeth. For restoring a tooth with a large filling or restoration, other options for stronger restorations and therefore longer lasting restorations can be considered in the form of onlays and crowns.

At Castle Dental, we feel it is our role to offer you all the options available for restoring a tooth. Making sure you understand the pros and cons of each option, we let you decide which form of treatment is most suitable for you.


What are onlays?

  • Onlays are commonly described as partial crowns or ¾ crowns.
  • They can be made of ceramic or gold.
  • They are strong.
  • They use the existing tooth as a base.
  • They are custom fitted to prevent further damage.

When onlays are the best treatment option

  • Molar teeth and premolar (back) teeth where half to three quarters of the tooth structure is missing.
  • Building up worn teeth.
  • Teeth under heavy bite where there has been a history of white fillings falling out or breaking.

Porcelain onlays are stronger than white fillings. They also require two visits approximately two weeks apart to complete.

However, if there is not enough tooth remaining as a base, a crown may be suggested.

Dental crowns

What are dental crowns?

  • Dental crowns are a treatment option for replacing missing tooth structure.
  • They are suitable when white fillings or onlays are not ideal.
  • They cover the whole tooth and are shaped in a way which looks and feels natural.
  • They can be made out of gold or porcelain.

They can be likened to a bike helmet. Helmets are designed to protect from trauma or injury. It is the same for a dental crown. The crown “locks-in” or “caps” the remaining tooth to protect it.

When dental crowns are the best treatment option

  • Any tooth with a significant loss of tooth structure (>75%).
  • Teeth that have not had any root canal treatment.
  • Any tooth were an onlay or a filling is unsuitable
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