Inlays and Onlays

Overview

Note: the second to the last tooth is a full crown as it covers the entire tooth. The last tooth is restored with an onlay.  An onlay is a more conservative treatment as less tooth structure is removed.

Note: the second to the last tooth is a full crown as it covers the entire tooth. The last tooth is restored with an onlay. An onlay is a more conservative treatment as less tooth structure is removed.

An Inlay is a method to replace lost tooth structure; an inlay is constructed in a laboratory and bonded into the tooth.

An Inlay is a method to replace lost tooth structure; an inlay is constructed in a laboratory and bonded into the tooth.

An inlay is a laboratory-constructed restoration that is placed between the cusp tips of your tooth and typically restores the area between your teeth as well. An onlay covers anywhere from one cusp tip to the entire biting surface, but not the entire tongue and cheek side of your tooth like a crown does. To the untrained eye, these restorations look like large white (composite) fillings; in reality, they are prepared much the same as a crown and sent to a dental laboratory for construction.

Why do I need an inlay or onlay?

A molar tooth with an Onlay that is constructed in a dental laboratory.

A molar tooth with an Onlay that is constructed in a dental laboratory.

When a tooth needs to be restored, but the area needing the restoration is too large for a filling and a crown would be considered excessive, an inlay or an onlay may be the restoration of choice. There are “rules” that dictate when a lab constructed restoration (such as an inlay, onlay or crowns) is indicated versus a filling. Large fillings do not support the long term health of teeth as well as a laboratory constructed restoration.

Advantages of inlays/onlays:

  1. They conserve tooth structure, as crowns require more tooth removal.
  2. They are a better restoration than a large filling because they are laboratory constructed and bonded into place.
  3. They are more attractive than a large silver (amalgam) filling.
  4. They are thought to strengthen your tooth once bonded into place.

Disadvantages:

  1. They are more time-consuming to prepare and insert.
  2. They are more expensive than a filling and about as expensive as a crown.
  3. There are many more margins exposed, allowing more potential contact with bacterial plaque, so are best placed in patients with superior oral hygiene.
  4. They are not the restoration of choice if you grind your teeth, unless made with gold.

What are the different types of inlays and onlays?

Porcelain inlays and onlays:

  • Very aesthetically pleasing restorations constructed by a lab or milled in the office and bonded into your tooth.
  • Probably the most popular; pressed porcelain is somewhat brittle until bonded to your tooth, when it takes on superior strength. Porcelain will wear your opposing teeth more than gold.

shutterstock_166386377Fiber-reinforced composite inlays and onlays:

  • Very aesthetically pleasing restorations constructed by the lab and bonded into your tooth preparation
  • Virtually disappear when bonded into the tooth
  • More kind to the opposing teeth, creating less wear, but not as strong as gold or porcelain.

Gold inlays and onlays:

  • Constructed by the lab and cemented (vs. bonded) into your tooth preparation made by your dentist
  • More kind to the opposing teeth than porcelain, creating less wear
  • Best utilized on people who grind their teeth (see Clenching and Grinding your Teeth: Bruxism); they are metal, which makes them very strong and metal is more kind to the teeth they chew against.