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Dental restorations can restore the natural appearance of a tooth by repairing decay (cavities), cracks, and other damage.

There isn’t a single option for restoration. For example, crowns and onlays serve similar purposes. But while adental crowncompletely covers the surface of a tooth, an onlay (or partial crown) covers only part of a tooth.

Here’s what you need to know about crowns and onlays, including how they differ, the benefits and downsides of each, and how to work with a dentist to decide which one is right for you.

Dental fillingscan treat minorcavitiesand damage. But some cavities and damage are too extensive for a filling. In this case, you might need a crown or onlay to restore the tooth.

Dental onlays repair damage on the cusp — the elevated part of the tooth surface. These are made from a porcelain or gold material, and they cover only the damaged part of the tooth.

If you have a severely damaged or decayed tooth, you may need a dental crown that fits completely over the tooth.

Crowns restore a severely worn down or broken tooth. Covering the entire tooth can stop further damage and possibly save the tooth.

Dental crowns are also made from a porcelain or gold material.

Here’s a visual guide to the differences between a dental crown and a dental onlay.

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Dental onlays or dental crowns may be used to repair teeth damaged by decay. Illustration by Wenzdai Figueroa

The extent of damage and the condition of your teeth determines whether you receive a dental crown or a dental onlay.

But it’s essential to understand the pros and cons of both restorative treatments before you decide to move forward with one or the other.

Here’s a guide to comparing the benefits and downsides of getting a dental crown or an onlay.

Dental Crown Dental Onlay
Pros Durable material (similar to onlay).
Repairs large or worn fillings.
Protects damaged or decayed tooth from further damage.
Restores the natural appearance of a tooth.
Helps reshape a tooth.
Maintains the integrity of a tooth after a root canal.		 Durable material (similar to crown).
Repairs and reshapes damaged tooth
Lowers the risk of future decay.
Restores natural tooth appearance.
More conservative procedure that preserves more of your tooth structure with less extensive preparation.
Cheaper than a dental crown.
Cons More extensive procedure than dental onlay.
Dental crowns can chip or break, needing more repair.
More expensive than a dental onlay.
May have sensitivity to hot or cold after a procedure.
Risk of an allergic reaction to the material.
Requires more than one appointment.		 Can be cheaper than or a similar cost to a crown.
Can chip or crack, requiring further repair.
May have sensitivity to hot or cold after a procedure.
Risk of an allergic reaction to the material.
Requires more than one appointment.
Can be more difficult to perform.

Treatment costs vary but generally fall in the following range for each type:

  • onlay:$650 to $1,200 per tooth
  • crown:$500 to $3,000 per tooth

Other factors that can determine cost include:

  • location of the toothin your mouth
  • how much repair needs to be doneto the tooth
  • the need for other proceduresalong with the repair
  • whether it’s an emergency serviceor an elective procedure
  • the material used— for example, metal often costs less than porcelain
  • insurance coverage— most dental plans cover part of the cost of a crown or onlay (sometimes up to 50 percent)
  • using an in-network or out-of-network provider— you’ll pay more out-of-pocket if you see a dentist outside of your insurance carrier’s network

If you don’t have dental insurance, you’re responsible for the entire cost. In this case, some dentists offer payment plans. You might also qualify fordental financial assistance programs.

Here’s what to expect from a dental crown and a dental onlay procedure.

Procedure for a dental crown

  1. Schedule an initial visit to prepare your tooth for the crown.The dentist will take X-rays and you’ll receive local anesthesia to numb the area.
  2. The dentist removes tooth decay or any damaged areas of the tooth.You might need aroot canalto remove bacteria from inside the tooth.
  3. The dentist shaves down the tooth to make room for the crown.Using a putty-like material, they’ll create an impression of the tooth.
  4. The dentist sends the impression to a laboratoryto customize a permanent crown to fit over the damaged tooth.
  5. At the end of your first appointment, the dentist covers the tooth with a temporary crown.You’ll need to wait about 1 to 2 weeks to receive the permanent crown. Some dental offices can make a crown or an onlay that’s ready on the same day.
  6. On your second visit, the dentist removes the temporary crownto prepare the tooth for the permanent crown.
  7. The dentist places the permanent crown over your toothto check the fit. They may make further adjustments to the tooth’s surface or the crown if the fit isn’t exact.
  8. If the crown fits properly, the dentist applies a numbing agentto the area around the tooth.
  9. The dentist cements the permanent crownover your tooth.

Procedure for a dental onlay

  1. On your initial visit, your dentist uses a local anesthetic to numb your mouthand then removes any tooth decay as well as the damaged section of your tooth.
  2. Using a putty-like material, the dentist creates an impression of your toothand sends this impression to a laboratory to create the permanent onlay. The dentist covers your tooth with a temporary onlay.
  3. On your second visit, the dentist removes the temporary onlayand ensures the correct fit of your permanent one.
  4. If the permanent onlay fits properly, the dentist numbs your mouth and permanently attaches the onlayto your tooth.

Dental crowns and onlays are durable and designed to last typically 5 to 15 years.

But particular factors could shorten their duration, including:

  • grinding your teeth
  • biting your nails
  • chewing hard or sticky objects
  • injury to the tooth or surrounding area

These can cause the material to break, crack, or chip and require early repair or replacement.

Onlays and dental crowns are safe, effective, and widely used treatments.

But some people can experience side effects or complications after the procedure, including:

  • sensitivity to hot and cold
  • pain that doesn’t get better over time

Pain and sensitivity often improve after a few days or weeks. If it doesn’t improve, see a dentist or seek urgent medical care if you can’t get an appointment with a dentist.

Some people may also have allergic reactions to metals used in crowns or onlays. Allergic reactions aren’t common, but see a dentist or doctor if you notice any of the following symptoms of an allergic reaction inside your mouth:

  • itching
  • redness
  • irritation with no other apparent cause

Tooth decay can worsen if left untreated and threaten the health of your tooth.

To protect your teeth, brush and floss daily, and don’t forget to schedule regular dental checkups every 6 months or so.

Also, be sure to see a dentist if you experience pain or discomfort between dental visits or after a dental procedure.