Inlays & Onlays

What Are Inlays and Onlays?

Inlays and onlays — sometimes called indirect fillings or partial crowns — are custom-fabricated restorations used to repair back teeth (molars and premolars) that have moderate-to-significant damage or decay. They occupy a middle ground between a standard filling and a full dental crown, making them an excellent choice when a filling would be too weak but a crown would remove too much healthy tooth structure.

The distinction between the two is based on where on the tooth they are placed: an inlay fits within the cusps (raised points) of a tooth, filling in a cavity or damaged area in the center. An onlay extends over one or more cusps of the tooth — a larger restoration that is sometimes called a "partial crown."

Materials Used

Porcelain/Ceramic: Tooth-colored and highly aesthetic. Excellent for visible teeth. Strong and stain-resistant.

Composite Resin: Tooth-colored. Can be completed in a single visit in some cases. Slightly less durable than porcelain over the long term.

Gold: The most durable option — gold inlays and onlays are considered one of the longest-lasting dental restorations available, with a lifespan of 20 years or more. The ADA notes that gold has been used in dentistry for over 1,000 years due to its proven durability. However, the metallic appearance makes gold less desirable for visible teeth.

Source: American Dental Association — Fillings & Gold Inlays (MouthHealthy.org)

Advantages Over Direct Fillings

Inlays and onlays are fabricated in a dental laboratory from precise impressions of your tooth — so they fit more accurately and have better strength characteristics than a direct filling placed chairside. For large cavities or teeth with significant structural damage, an inlay or onlay is more conservative than a crown (less tooth removal) while being more durable than a large filling. They also seal the tooth edges with greater precision, reducing the risk of future decay under the restoration.

The Procedure

The inlay or onlay process typically requires two visits. At the first appointment, Dr. Li removes the damaged or decayed tooth tissue and prepares the area. Digital or physical impressions are taken and sent to a dental laboratory. A temporary restoration protects the tooth in the meantime. At the second visit, the custom inlay or onlay is permanently bonded to the tooth with a strong dental adhesive, checked for fit and bite, and polished.

Is an Inlay or Onlay Right for Me?

If you have a tooth with a large filling that is failing, significant decay that a filling alone cannot address, or a cracked cusp that doesn't require a full crown, an inlay or onlay may be the most conservative and durable solution. Dr. Li will evaluate your tooth at your examination and recommend the most appropriate restoration for your specific situation. Contact us to schedule a consultation.