What are Inlays and Onlays Used For? 


Aside from dental fillings, inlays and onlays are two other methods for filling cavities and restoring teeth. These can usually last for more than 10 years because they are made of durable materials such as ceramic.

These materials can be considered in addition to dental restorations and crowns. Dental fillings are normally for small cavities, whereas inlays and onlays are more ideal for larger cavitations. Crowns however, are the preferred choice for teeth with severe damage (e.g. crowns are usually needed following a root canal).

Dental Inlays

With an inlay, the cavity is filled with a single, solid piece of material that is fabricated in a lab, and they are typically made of materials like gold or ceramic. The inlay must be made precisely to fit the dimension of the empty space; otherwise, food and bacteria will enter, resulting in further problems such as decay. An inlay does not contract as much as compared to a dental filling. Hence, it is a better material to use since there is a lower chance of marginal leakage occurring, reducing the risk of bacteria ingress. Inlays are considered a stronger and more durable restoration. Therefore, inlays are a more reliable long-term choice of material.

Dental Onlays

Onlays visually looks like partial crowns and are chosen for larger sizes cavities when dental restorations or inlay are not suitable due to the limited amount of remaining tooth structure. The main distinct difference between an onlay and an inlay is that an onlay provide cuspal coverage, whereas an inlay will only occupy the internal area of the cavity. Just like an inlay, an onlay is custom-made to fit the space exactly. Conversely, a crown will cover the entire biting surface of the tooth, and often extends to the gum line.

Compared to a crown, an onlay is a less aggressive restorative option and involves minimal tooth removal. The cost of an onlay is also more economical as compared to a crown.

Preparing for inlays and onlays: the process explained

The procedure for getting a dental inlay or onlay is relatively pain free and simple.

A brief overview of the procedure are as follows:

The dentist will clean out the decay.

Your dentist will take an impression of your tooth (this might require a 3D scan).

The impression will be sent to a lab to create your inlay or onlay.

Your dentist will bond your inlay or onlay to your tooth on a separate visit.

To summarize, here are the pros and cons of inlays and onlays:


  • Lasts longer than fillings
  • Excellent for repairing damage to tooth grooves and biting surfaces.


  • More expensive than fillings
  • Inlays and onlays may require two appointments

Dental fillings, inlays, onlays and crowns are are all different methods used to restore tooth structure.

Your dentist at iSmile Dentistry will help you choose the right decision on the type of restorative material most ideal for your case based on our clinical assessment. If you are interested in any cosmetic or restorative dental treatment, please get in touch with our friendly team at 9030 4310