Inlays and Onlays: The Conservative Alternative to Crowns

When you have a cavity or tooth damage, your treatment options typically fall into a few categories. Small cavities are treated with fillings, while larger cavities or teeth with substantial damage are often treated with crowns. But what if your cavity or damage is in between those two extremes? What if a filling seems too small and temporary, but a crown requires removal of too much healthy tooth structure?

Inlays and onlays are restorations that occupy a middle ground. They preserve more tooth structure than a crown while providing more support and durability than a filling. For some patients, an inlay or onlay represents the ideal balance between conservation of natural tooth structure and restoration longevity.

Understanding Inlays

An inlay is a restoration that fits inside the cusps (points) of a back tooth. The restoration is fabricated in a laboratory, either in ceramic, porcelain, composite resin, or metal, and then cemented into place in the tooth. An inlay restores the inside portions of the tooth that have been damaged by decay or fracture, but it does not cover the cusps.

To place an inlay, Dr. Bonin removes the decay and shapes the preparation to match the custom restoration. Because an inlay only covers the internal surfaces of the tooth, less tooth structure is removed compared to a crown. The remaining natural tooth structure, particularly the cusps, is preserved.

Inlays are most appropriate for cavities that are moderate in size and located in the internal portions of back molars or premolars. They provide excellent durability and can last fifteen to twenty years or longer with proper care, which is comparable to the longevity of crowns.

Understanding Onlays

An onlay is similar to an inlay but extends further. An onlay covers not only the internal portion of the tooth but also one or more of the cusps. In essence, an onlay is bigger than an inlay but smaller than a crown because it does not cover all four cusps and does not extend down the sides of the tooth.

Onlays are appropriate for cavities or damage that is more extensive than what an inlay can handle, but not so extensive that a full crown is necessary. An onlay might be recommended if decay extends into one or two cusps of a molar, or if a previous large filling has weakened the tooth and you want to reinforce it.

Like inlays, onlays are custom-fabricated restorations that are cemented into place. They provide excellent durability and aesthetic appeal, especially if fabricated from ceramic or porcelain.

Inlays and Onlays vs. Fillings

Compared to a filling, an inlay or onlay offers several advantages. Fillings are not as durable as inlays or onlays, especially for large cavities in high-stress areas. A large filling may succeed for five to ten years, but an inlay or onlay is more likely to last fifteen to twenty years.

Fillings bond to the tooth using adhesive techniques, and these bonds can deteriorate over time, especially at the margins where the filling meets the tooth. This can lead to leakage and secondary decay. Inlays and onlays are milled or carved to precise specifications and cemented with strong adhesive cements, creating a more durable restoration that is less prone to leakage.

Fillings can also stain and discolor over time, particularly composite fillings. Inlays and onlays made from ceramic or porcelain resist staining better and maintain their appearance for longer.

Inlays and Onlays vs. Crowns

The primary advantage of an inlay or onlay compared to a crown is preservation of tooth structure. A crown covers the entire tooth and requires significant removal of healthy tooth material. An inlay or onlay preserves the cusps and allows more of your natural tooth to remain intact.

Teeth that are treated more conservatively tend to remain healthier long-term. By preserving more natural tooth structure with an inlay or onlay, you may be protecting the tooth against future problems that sometimes develop in teeth that have been extensively reduced for crowns.

However, inlays and onlays have a limitation that crowns do not have. If a tooth is so badly damaged that the cusps are also compromised, an inlay or onlay cannot adequately support the tooth. In that case, a crown becomes necessary.

The Placement Procedure

Placing an inlay or onlay requires two appointments. At the first appointment, Dr. Bonin removes the decay, shapes the tooth to accommodate the restoration, and takes an impression. You will wear a temporary filling while the inlay or onlay is fabricated in the laboratory, which typically takes one to two weeks.

At the second appointment, the temporary filling is removed and the custom restoration is cemented into place. The restoration is then shaped slightly if needed to ensure your bite is correct.

Some offices use CAD/CAM technology to mill inlays and onlays in the office in a single appointment, similar to same-day crowns. This technology is becoming more common and can reduce the treatment timeline significantly.

The Cost Consideration

Inlays and onlays typically cost more than fillings but less than crowns. However, the specific pricing varies depending on the size of the restoration and the material chosen. Your dental insurance may have different coverage levels for inlays, onlays, fillings, and crowns.

When considering the cost, remember to factor in longevity. A filling might be less expensive initially but may need replacement in five to ten years. An inlay or onlay costs more upfront but may last fifteen to twenty years or longer, potentially saving you money over the long term.

Material Options

Inlays and onlays can be fabricated from several materials. Composite resin is durable and tooth-colored, making it a good choice for visible areas. Ceramic or porcelain restorations are extremely durable, very aesthetically pleasing, and highly resistant to staining.

Gold is an excellent material that has been used for many decades. Gold inlays and onlays are exceptionally durable and can last for decades. The primary disadvantage is appearance; gold is visibly metallic and is rarely chosen for front teeth, though it works well on back molars where it is not visible.

At Bonin Dental Care, Dr. Bonin will discuss material options with you based on the location of the restoration and your aesthetic and functional preferences.

Care and Maintenance

Inlays and onlays require the same care as your natural teeth. Brush twice daily, floss daily, and visit your dentist regularly. Avoid chewing on hard objects that could damage the restoration or underlying tooth.

With proper care, an inlay or onlay can remain in place and function well for many years. Regular dental visits allow Dr. Bonin to monitor the restoration and detect any problems early.

Is an Inlay or Onlay Right for You

The decision between a filling, inlay, onlay, or crown depends on the size and location of the cavity, the amount of remaining healthy tooth structure, and your long-term goals. Dr. Bonin will evaluate your specific situation and recommend the treatment that best serves your interests.

If you have a moderate-sized cavity or damage to a back tooth that exceeds what a filling can handle, an inlay or onlay might be an excellent option that preserves more of your natural tooth while providing excellent durability.

If you want to discuss your treatment options for a cavity or tooth damage, contact Bonin Dental Care in Windsor to schedule a consultation with Dr. Bonin. We will help you understand your options and choose the restoration that is best for your tooth and your long-term oral health.