Dental Inlay and Onlay

We all take good care of our teeth. All of us brush our teeth twice a day, floss after every meal and use the best mouthwash to keep our pearly whites healthy. But in spite of everything, we get a cavity and that too in one of our back teeth.

You may feel that filling is the only option, but there are other options available as well. These options are dental inlays and onlays, which are also known as indirect fillings.

Your dentist will decide the kind of restoration that you may require based on the damage in your teeth. (1)

Inlays and onlays are given by a dentist when the damage is too extensive to be restored with a metal or composite filling but not extensive enough which might require a full crown.

It is essential to get your teeth restored when you get a cavity, to limit the damage and reinstate the health of your teeth. Let’s continue in this article to know more about inlays and onlays and also know whether they are the best option or not.

What is an inlay?

An inlay is a pre-molded filling, fabricated outside the mouth in a laboratory, which is fitted into the grooves of the tooth and does not extend over the cusps of the tooth.

What is an onlay?

An onlay is an indirect filling, also fabricated outside the mouth, which covers one or more cusps of the tooth and extends over the biting surface of the tooth.

When to get an inlay or an onlay?

An inlay or an onlay is indicated where there is a need to protect damaged tooth structure without additional removal of tooth structure which is required in case of a crown. It allows the dentist to conserve more of your natural tooth.

They are also indicated when placing a direct filling is challenging to achieve proper shape and margins of the restoration.

Dental inlays or onlays can also be used to replace or remove old fillings.

When an inlay or an onlay is not a good option?

Inlays and onlays may not the best options for you in the following conditions –

1. Poor oral hygiene

Inlays and onlays are not suitable for people with poor oral health. There is a high risk of recurrence of caries in such cases, which can lead to failure of the restoration.

The dentist should strive to reduce the risk of caries in the patient before any indirect restorative procedures.

2. Parafunctional habits or abnormal occlusal forces

Inlays or onlays are contradicted in patients who have the habit of bruxism or clenching their teeth at night or people with heavy occlusal forces.

Most of these restorations are made from porcelain which can fracture easily under abnormal occlusal forces.

3. In patients who are under the age of 16

Young children should not be given inlays or onlays as their pulp chambers are quite large where the wider dentinal tubules will add stress on the pulp.

It can also lead to damage to the nerve supply of the vital tooth. Also, children are unable to cope with invasive dental treatments and lengthy procedures.

Process of fabrication

The primary aim of fabricating an inlay or onlay is to preserve the natural tooth as much as possible. Both dental inlay and onlay are made using very similar procedures. Usually, this procedure completes in two appointments.

In the first appointment, the dentist numbs the area to be treated with local anesthesia and removes all the decayed part of the tooth. If an old filling is being replaced, it is also removed in the same manner.

After a cavity has been prepared, the dentist takes an impression of it using dental putty that fits over the teeth. This impression is sent over to a laboratory where an inlay or onlay is prepared based on it.

The dentist will provide a temporary restoration until the next appointment to protect the tooth.

In the second appointment, the dentist removes the temporary restoration and checks if the inlay or onlay fits the tooth.

After the dentist ensures that it fits perfectly, the inlay or onlay is bonded to the tooth using a strong resin adhesive. After that, the restoration is polished to give it a smooth and aesthetically pleasing finish.

Each appointment can take about an hour, with the first appointment taking a slightly longer time than the second time. The new restoration may feel odd, and you may feel some discomfort, but it lasts for a few days only.

Methods of fabrication

There are several fabrication methods for inlays and onlays, based on the restorative material used:

  • Lost wax technique
  • CAD-CAM (2)
  • Slip-casting technique
  • Direct restorative technique

Materials used for fabrication

In the past, gold material was used for fabrication inlays and onlays. But its use is fading now due to the increased demand for more aesthetic and natural looking restorations.

These are some of the materials used in fabricating inlays and onlays –

  1. Gold
  2. Ceramic
  3. Composite
  4. Metal-ceramic

What does an inlay or an onlay cost?

The cost for a dental inlay or onlay depends on a variety of factors, mainly the level of the dentist’s expertise and the material used. A dental inlay or onlay costs roughly the same.

It can range from $650 to $1200 per tooth, with an average cost of $900. Most insurance plans tend to cover all or at least some of the price for this treatment procedure.

Inlays and Onlays vs. traditional filling vs. a crown

Inlays and onlaysTraditional fillingCrown
  • Reserved for large cavities with extensive damage
  • Durable and long lasting- made from hard-wearing materials (3)
  • Increase tooth strength by 75%
  • Aims to preserve natural tooth structure as much as possible
  • Cheaper than a crown
  • Requires at least two visits to the dentist
  • Done in cases where damage is less extensive
  • Made from amalgam or composite, less durable and sturdy
  • Can reduce the tooth strength by 50%
  • Out of the three options, it preserves the most tooth structure
  • Cheapest option amongst the three
  • Requires only one visit
  • Used to replace the entire tooth structure
  • Made from ceramic, metal or combination of both
  • Extensive tooth structure is lost
  • Most expensive option out of the three procedures
  • Requires multiple visits

Benefits of choosing inlays and onlays

Every treatment procedure comes with its own set of advantages and disadvantages. The benefits of going with dental inlays or onlays far outweigh the drawbacks. Some of these benefits are –

  • Ability to have a restored tooth that looks completely natural.
  • It is preserving as much natural tooth as possible.
  • It is the perfect option for restoring difficult cavities that are between teeth.
  • Extremely strong and stable, allowing you to chew anything without fear of damage to the teeth. (4)
  • Creates a better seal and preventing bacteria from entering the cavity and causing more tooth decay.
  • Extended longevity of the restoration
  • Prevents staining which comes with eating and drinking different foods and beverages.

Take away message

Traditional composite fillings area great treatment option but it is not a viable option when there is extensive tooth damage. Inlays and onlays are conservative dental restoration option.

Inlays or onlays are recommended in situations where composite fillings won’t provide enough support, but the damage is not so bad that it needs a crown. The process of receiving an inlay or an onlay requires two visits to the dentist.

It is a sturdy, durable and long-lasting restoration option which increases the longevity and strength of the natural tooth.

Inlays and onlays may be more expensive than a traditional filling, but they are a lot cheaper than getting a crown. Remember to brush twice a day and floss regularly, even after you get any restoration.