Complete Guide To Dental Onlays: Process, Risks, Cost, and More

Dentists offer a wide range of treatments for repairing damaged teeth. The goal is to restore their natural function and appearance in the most durable but least invasive way possible. When a filling isn’t the best option but a crown is overkill, a dental onlay could be the solution.

3d render of teeth with dental onlay filling

What Is A Dental Onlay?

A dental onlay is a solid, custom filling used to repair broken or decayed molars and premolars. It’s a more aggressive treatment than a typical filling but more conservative and less expensive than a crown. The difference lies in how the damaged area is filled.

Conventional fillings are made from amalgam or composite material mixed at chairside. Onlays and crowns are made in a lab from a mold of your tooth using gold, porcelain or composite resin. Gold was once the material of choice because of its strength and malleability. It’s stain-resistant, easy to shape and nearly impossible to fracture.

Today, porcelain and composites are more popular materials because they look like natural teeth and blend in better aesthetically, but neither is as strong as gold. Dentists often recommend gold onlays for the back molars responsible for chewing and porcelain or composite for the premolars you can see when you smile.

How Are Dental Onlays Applied?

Onlays are applied by a dentist or prosthodontist, a specialist in restoring damaged teeth. The procedure varies slightly based on the tooth involved and the extent of the damage, but in general, here’s what you can expect:

1. You’ll receive a local anesthetic. Injected into the gum near the affected tooth, it prevents pain.

2. The dentist will drill out decay, removing the damaged parts of your tooth.

3. A precise mold is made using dental putty. If you’re opting for a porcelain or ceramic onlay, you’ll choose the shade.

4. If your dentist has the equipment, they’ll make your permanent onlay and apply it during the same visit. If not, the mold is sent to a lab, and you’ll receive a temporary filling.

5. The onlay may take a few weeks to create. You’ll be given an appointment to apply it when it arrives. Anesthetic is usually optional.

6. Finally, the dentist will smooth the onlay to ensure a comfortable bite and polish the surface to eliminate rough spots that could irritate your tongue. Some dentists apply additional resin to harden the remaining tooth.

What Are the Potential Complications of Dental Onlays?

Onlays are a low-risk procedure, but complications can occur, including:

• An allergic reaction to the anesthetic or onlay material
• Nerve injury caused by the anesthetic injection
• Injury to the mouth or gums from instruments or debris
• Additional tooth decay if the onlay seal deteriorates prematurely
• Damage to the tooth or onlay caused by the contraction or expansion of composite materials

You can reduce the risk of complications by carefully following pre- and post-procedure instructions and informing your dentist if you have allergies. You may be asked to avoid chewy or crunchy foods for a few days.

Who Is a Candidate for a Dental Onlay?

Fillings are a quick, same-day option for repairing small defects. But when the damage is extensive or involves the cusps of the tooth — the elevated points that help grind your food — an onlay is a better choice because it handles vigorous chewing and can strengthen a generally weak tooth by up to 75 percent.

Also called an indirect filling or a partial crown, it can restore up to 50-percent of a tooth’s surface and lasts 15-30 years. Some dentists recommend onlays even when conventional fillings will do because it’s a better long-term value.

What Is The Difference Between A Dental Onlay And A Crown?

Crowns are a more complete restoration, covering the entire bite surface — but more isn’t always better. In order to apply a crown, the dentist will need to remove more of the tooth, even if it is healthy, in order to apply the crown. Onlays are generally preferable because they’re equally durable, cost less and preserve more of the natural tooth.

How Much Do Dental Onlays Cost?

Like most restorative treatments, the cost of an onlay varies based on:


Back molars are more challenging to work on and require more of the dentist’s time.


Large onlays require more material to fabricate, increasing the cost proportionally.


Similar in price, gold and composite onlays are the most affordable. Porcelain is more expensive.


Difficult restorations, general anesthesia, and medical considerations increase the complexity and price of onlays. But most factors are predictable and should be included in the estimate.

Nationwide, costs range from $650-$1250 per tooth — an average of $900.While dental insurance covers most of the cost of fillings, onlays are considered major restorative procedures and are typically covered at 50 to 75 percent. Plan to spend $200-$625.

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