Inlays / Onlays

Inlays and onlays are dental restorations that cover back teeth. The difference between an inlay and an onlay is that an inlay covers a fairly small part of the biting surface of a back tooth while an onlay extends over the biting surface and on to other parts of the tooth. Both of these restorations are cemented into place and cannot be taken off.

Frequently Asked Questions 


1. What materials are in an Inlay/Onlay? 


Inlays are made of two types of materials: 


     1. Porcelain - most like a natural tooth in color

     2. Gold Alloy - strongest and most conservative in its preparation


2. What are the benefits of having an Inlay/Onlay? 


Inlays and Onlays restore a tooth to its natural size, shape and–if using porcelain– color. They improve the strength, function and appearance of a broken down tooth that may otherwise be lost.


3. What are the risks of having an Inlay/Onlay? 


In having an inlay/onlay, some inherent risks exist both to the tooth and to the restoration itself. The risks to the tooth are:


  • Preparation for an inlay/onlay weakens tooth structure and permanently alters the tooth underneath the restoration.
  • Preparing for and placing an inlay/onlay can irritate the tooth and cause “postoperative” sensitivity which may last for up to 3 months.
  • The tooth underneath the inlay/onlay may need root canal treatment about 5% of the time during the lifetime of the tooth.
  • If the cement seal at the edge of the inlay/onlay is lost, decay may form at the juncture of the restoration and tooth.


The risks to the inlay/onlay are:


  • Porcelain may chip and metal may wear over time.
  • If the tooth needs a root canal treatment after the inlay/onlay is permanently cemented, the procedure may fracture the restoration and the inlay/onlay may need to be replaced


4. What are the alternatives to Inlays/Onlays? 


  • Alternatives to placing an inlay/onlay are to either place a crown or a direct restoration such as tooth colored or silver fillings.
  • Crowns are less conservative in their preparation and therefore weaken remaining tooth structure more than inlays/onlays.
  • Composite and amalgam restorations remove decay and may restore teeth to their original form but are limited because they:

- Do not improve the strength of broken down teeth.

- Do not improve the long term function and aesthetics of broken down teeth as well as inlays/onlays. 


5. How can an existing bite affect an Inlay/Onlay? 


Excessive bite forces may lead to the restoration chipping or breaking. 


6. Are there any post-treatment limitations once I have an Inlay/Onlay? 


  • Porcelain on an inlay/onlay may have a good color match with adjacent natural teeth when the restoration is placed but less of a match as your natural teeth age.
  • An inlay/onlay may chip or break if used for abnormal activities (e.g., biting fishing line, sewing thread or finger nails, opening bottles).

Frequently Asked Questions 


1. What materials are in an Inlay/Onlay? 


Inlays are made of two types of materials: 


     1. Porcelain - most like a natural tooth in color

     2. Gold Alloy - strongest and most conservative in its preparation


2. What are the benefits of having an Inlay/Onlay? 


Inlays and Onlays restore a tooth to its natural size, shape and–if using porcelain– color. They improve the strength, function and appearance of a broken down tooth that may otherwise be lost.


3. What are the risks of having an Inlay/Onlay? 


In having an inlay/onlay, some inherent risks exist both to the tooth and to the restoration itself. The risks to the tooth are:


  • Preparation for an inlay/onlay weakens tooth structure and permanently alters the tooth underneath the restoration.
  • Preparing for and placing an inlay/onlay can irritate the tooth and cause “postoperative” sensitivity which may last for up to 3 months.
  • The tooth underneath the inlay/onlay may need root canal treatment about 5% of the time during the lifetime of the tooth.
  • If the cement seal at the edge of the inlay/onlay is lost, decay may form at the juncture of the restoration and tooth.


The risks to the inlay/onlay are:


  • Porcelain may chip and metal may wear over time.
  • If the tooth needs a root canal treatment after the inlay/onlay is permanently cemented, the procedure may fracture the restoration and the inlay/onlay may need to be replaced


4. What are the alternatives to Inlays/Onlays? 


  • Alternatives to placing an inlay/onlay are to either place a crown or a direct restoration such as tooth colored or silver fillings.
  • Crowns are less conservative in their preparation and therefore weaken remaining tooth structure more than inlays/onlays.
  • Composite and amalgam restorations remove decay and may restore teeth to their original form but are limited because they:

- Do not improve the strength of broken down teeth.

- Do not improve the long term function and aesthetics of broken down teeth as well as inlays/onlays. 


5. How can an existing bite affect an Inlay/Onlay? 


Excessive bite forces may lead to the restoration chipping or breaking. 


6. Are there any post-treatment limitations once I have an Inlay/Onlay? 


  • Porcelain on an inlay/onlay may have a good color match with adjacent natural teeth when the restoration is placed but less of a match as your natural teeth age.
  • An inlay/onlay may chip or break if used for abnormal activities (e.g., biting fishing line, sewing thread or finger nails, opening bottles).
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