Crowns & Onlays



- Crowns & Onlays -

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A crown is a type of dental restoration that fits over a tooth, much like a thimble does over a finger. In doing so, it recreates the natural shape of the tooth as well as helping to reinforce and strengthen the underlying tooth structure.

An onlay is similar to a crown in that it fits over the tooth. However, whilst a crown usually covers all the tooth structure visible above the gum, an onlay can be used to overlay the missing tips of a tooth without necessarily extending all the way to the gum, often making it preferable through less destruction of tooth structure.

There are a number of reasons why a crown or onlay would be needed:

  • To restore teeth which have been weakened by decay, large fillings and root canal treatments. As they are very strong, they usually last much longer than fillings
  • Since they sit over a tooth, they can also be used to improve the appearance of a tooth.
  • To restore the shape, appearance and function of a damaged tooth.
  • To help hold a bridge or denture in place.


  • Gold (precious metal) - This is a very useful material for onlays and some crowns, as it is strong and long lasting. Aesthetically they are more visible due to their colour although this is balanced by the fact that they can be made very thin; thus less tooth needs to be cut away during the preparation stage, meaning that more tooth is preserved. In addition, the alloy used is 'biomimetic'. This means that they mimic natural tooth structure as they are quite inert, as well as being of similar hardness to natural tooth. As a result, the restoration is quite sympathetic to the tooth biting against it.
  • Porcelain bonded to precious metal - Most crowns are made of an underlying thimble of gold alloy overlaid with porcelain to produce a strong, long lasting natural looking restoration. Due to their superior aesthetics, they are a good choice for most people. However, in order to produce this, more tooth needs to be cut away than with gold. Porcelain is harder than natural tooth which means it is less sympathetic to the tooth biting against it.
  • Porcelain - This is a modern technology used to create crowns and onlays made entirely of porcelain. The resulting teeth look extremely natural, as the natural translucency of a tooth can also be reproduced. Crowns made on the front teeth where aesthetics are vitally important are frequently made from pure porcelain.


An x-ray is taken to confirm the quality of the underlying tooth and verify the health of the nerve and surrounding bone. A local anaesthetic is used to numb the area, and the shape of the tooth modified by the dentist to allow space for the crown or onlay to fit over the remaining structure. This is then recorded by a mould, which is sent to a qualified (British) dental laboratory who manufacture the restoration for your tooth. This appointment usually takes an hour, and finishes with a temporary plastic restoration being firmly cemented into place to keep the tooth feeling normal and comfortable until the next appointment.

You may be asked to to attend the laboratory to have the colour of your crown porcelain matched to your natural teeth. Usually two weeks later, a second shorter appointment of roughly 30 minutes is needed to fit the final crown.

Heathwood Dental Practice

1 Kings Road, Crowthorne,

Berkshire. RG45 7BF

Tel. 01344776933

A Gold Crown
An Zirconia Porcelain Crown and a Porcelain Bonded to Metal Crown
An Emax Porcelain Onlay

A Gold Crown

A Porcelain Crown and a Porcelain Bonded Crown

A Porcelain Onlay

Home    /    Cosmetic Treatments    /    Crowns & Onlays


Heathwood Dental Practice

1 Kings Road, 



RG45 7BF

T. 01344776933

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