The Difference Between Inlays and Onlays

When a filling isn’t enough and a crown feels like too much, inlays and onlays step in. Both options serve the same goal: restoring your tooth in a strong, natural-looking way.

So, what’s the difference between an inlay and an onlay?

At Healthy Smile Dental in Woodridge, Illinois, Hannah Baek, DDS, guides patients with expert dental health recommendations. If you have a damaged tooth, understanding the difference between inlays and onlays can help you make an informed decision about your dental care. 

What’s an inlay?

An inlay is a restoration that fits into the grooves of a tooth, specifically within the cusps, the raised edges of your molars. We typically use inlays when the damage is too extensive for a filling but not significant enough to require a crown.

Inlays are ideal when the tooth structure around the damaged area is still strong.

We begin by removing the decayed or damaged portion of the tooth. Then, we take a digital scan or impression to create a perfectly shaped inlay, usually made from porcelain or composite resin. A dental lab fabricates the piece to match the shape and color of your tooth. 

Once it’s ready, we bond the inlay in place, creating a seamless and durable repair.

What’s an onlay?

An onlay is similar to an inlay but covers a larger portion of the tooth. Instead of sitting only inside the grooves, an onlay extends over one or more of the tooth’s cusps. It’s a good option for teeth that have more significant damage but sufficient healthy structure to avoid a crown.

As with an inlay, we remove the damaged area and prepare the tooth for the restoration. Then, we create a mold or digital scan, and a lab customizes the onlay to fit your tooth precisely. Once it’s complete, we place and bond it to the tooth, ensuring a strong and natural-looking fit.

Onlays are often called partial crowns because they restore much of the tooth’s surface without requiring full coverage. They allow us to preserve as much of your natural tooth as possible while still reinforcing it.

Why choose one over the other?

The primary difference between inlays and onlays lies in the extent of the tooth's repair needs. 

If the damage is confined to the chewing surface and doesn’t affect the cusps, an inlay is usually the best option. If the damage extends beyond that and compromises the outer edges or cusps, an onlay is the better choice.

We examine the tooth, take images if needed, and discuss the best option with you. The goal is always to preserve as much of your natural tooth as possible while ensuring long-term function and appearance.

Why not just get a filling or a crown?

Fillings are great for small cavities or minor damage. But when the area needing repair becomes too large, a filling may not provide enough support. In those cases, the filling can fail or cause the tooth to crack further.

Crowns, on the other hand, require us to remove more of the natural tooth to place the full cap. When you don’t need that much coverage, an inlay or onlay gives you a more conservative option. They provide strength and protection while preserving healthy tooth structure.

Make the right choice for your smile

Both inlays and onlays provide strong, lasting solutions that keep smiles healthy and looking natural. Contact the Healthy Smile Dental office by phone or online today for expert advice on your oral health.