Small cavities need fillings, and badly damaged teeth need crowns, right? But what happens when a tooth falls somewhere in between?
Introducing dental inlays and onlays. Sometimes called “partial crowns,” these custom restorations are designed specifically to fit your tooth’s shape, size, and bite and are used to repair moderate decay or fractures while preserving as much healthy tooth structure as possible.
Both offer a strong, long-lasting, and conservative solution that bridges the gap between a simple filling and a full crown.
What is a Dental Inlay?
Fitting neatly inside the tooth’s natural contours, a dental inlay is a custom-made restoration used to repair damage within the grooves of a tooth’s chewing surface (without extending over the raised points on the tooth known as the cusps).
Dentists typically recommend an inlay when:
- A cavity or fracture is too large for a standard filling
- The tooth needs more strength and stability than a filling can provide
- Enough healthy tooth structure exists to avoid a full crown
Because they’re fabricated to fit the tooth precisely, inlays create a tight seal that helps prevent future decay and restores the tooth’s natural shape and function. Compared to large fillings, inlays are stronger, more durable, and more resistant to wear, making them a reliable option for molars and premolars.
What is a Dental Onlay?
While an inlay fits inside the chewing surface, an onlay extends over one or more of the tooth’s cusps, making it a good option when the damage is more extensive but the tooth is still strong enough to avoid a full crown.
Dentists often recommend an onlay when:
- A cavity or fracture affects one or more cusps
- A large portion of the chewing surface needs reinforcement
- A crown would require removing more healthy tooth structure than necessary
Once bonded in place, an onlay restores the tooth’s shape, strength, and function while preserving as much natural enamel as possible. They’re durable and especially useful for molars and premolars to help prevent future fractures in teeth that are weakened but still salvageable.
How are Inlays and Onlays Made?
After the dentist removes the decay or damaged tooth structure, they take either a digital scan or a traditional impression of the tooth to create an exact model that a dental lab or an in-office milling system uses to craft the restoration.
Inlays and onlays can be made from several durable materials, including:
- Porcelain – Blends naturally with surrounding teeth
- Composite resin – A tooth-colored option often used for smaller restorations
- Gold – Known for exceptional strength and longevity
Most inlays and onlays are created in a dental laboratory, which typically takes one to two weeks. During this time, a temporary restoration may be placed to protect the tooth. Some dental offices use technology known as “chairside economical restoration of esthetic ceramic” (CEREC) to design and mill the restoration right in the office, allowing patients to receive their inlay or onlay in a single visit.
What to Expect During an Inlay or Onlay Procedure
Similar to preparing for a filling, your dentist begins by examining the tooth and removing any decay or damaged enamel to create a clean and stable surface that will securely hold the inlay or onlay.
Once the tooth is prepared, the dentist takes either a traditional impression or a digital scan to create an exact model of your tooth used to design the custom restoration. If your inlay or onlay is being made in a dental lab, the dentist will place a temporary filling or temporary onlay to protect the tooth and prevent sensitivity while the final restoration is being fabricated.
At your next visit, the dentist checks the fit, color, and bite, and once everything feels right, the restoration is permanently bonded to the tooth with a dental adhesive. The dentist then polishes the restoration and makes any final adjustments.
Most patients can return to normal eating and daily activities right away. Some mild sensitivity is possible for a day or two.
Durability, Longevity, and Cost of Inlays and Onlays
With proper care, inlays and onlays typically last 10 to 30 years, depending on the material used and the patient’s oral habits. The Journal of the American Dental Association reports ceramic inlays and onlays boast a 10-year success rate of up to 83.6%, and traditional cast gold onlays are even more durable.
To maximize longevity, dentists recommend:
- Brushing and flossing daily
- Attending regular dental checkups
- Avoiding habits like chewing ice or biting hard objects
- Wearing a nightguard if you grind your teeth
Because inlays and onlays distribute chewing forces more evenly than large fillings, they can help protect the tooth from future fractures.
The cost of an inlay or onlay generally falls between that of a filling and a full crown and can depend on the material used, where it’s made, the size and location of the tooth, and your insurance coverage. (Many insurance plans cover inlays and onlays similarly to crowns.)
While they may cost more upfront than a filling, their strength and longevity often make them a cost-effective choice over time.
Making an Informed Choice About Inlays, Onlays, and Crowns
Dental inlays and onlays offer a strong, conservative solution for teeth that need more support than a filling can provide but aren’t damaged enough to require a full crown. By preserving as much healthy tooth structure as possible, these restorations help maintain the tooth’s natural strength while providing long-lasting protection against future decay or fractures.
If you’ve been told you need more than a filling but less than a crown, an inlay or onlay may be the ideal middle-ground solution to restore your tooth’s health, function, and appearance for years to come. Ready to learn more? Find a dentist near you who can help.