Inlays and Onlays: Less Invasive Than a Crown

When a back tooth is too damaged for a simple filling, many people assume the only answer is a full crown. Often it isn’t. Inlays and onlays are custom-made, bonded restorations that repair the damaged part of a tooth and leave the healthy part alone. An inlay fits inside the tooth; an onlay also rebuilds one or more of the biting cusps. Because far less healthy tooth is removed than for a crown, they are the less invasive choice whenever the damage allows it.

This article explains how inlays and onlays compare with fillings and crowns, who they suit, how they are made and placed at the Timonium office of Dr. Steven W. Haywood, DDS, and how to care for them.

What inlays and onlays are

At the practice, inlays and onlays are part of what are called “ultimate dental fillings”: bonded ceramic, resin or processed composite restorations that are among the longest-lasting and strongest dental restorations, with lifetime potential. They are made from materials that match your teeth and are designed to be undetectable.

Inlays

When only part of a tooth is damaged, an inlay is bonded inside the remaining structure, within the cusps of the tooth. It can restore strength equal to or greater than that of a crown or the original tooth.

Onlays

An onlay restores part of the biting cusp of a tooth and restores its structural integrity. Onlays are sometimes called “inside crowns” because they are strong while conserving the healthy parts of a damaged tooth, where many traditional offices would place a full crown and needlessly sacrifice healthy structure.

Indirect restorations

Unlike a regular filling, which is placed and shaped directly in the tooth, an inlay or onlay is made outside the mouth from an impression of your prepared tooth and then bonded in place in one piece. Most tooth-colored inlays and onlays are custom fabricated in the practice’s own lab.

Why less invasive matters

A tooth never grows back the structure that is drilled away. The practice’s approach is based on a simple principle: research has shown that the less a tooth is reduced, the longer it survives. That is why the most conservative restoration that will do the job is always the first recommendation, and crowns are only needed when a tooth has been completely damaged.

Crown preparation removes more tooth

To fit a crown, the tooth has to be shaped on every side so the cap can slide over it. Healthy enamel that was not damaged at all is often removed in the process. An onlay covers only what needs covering.

Bonding adds strength

Traditional fillings have been shown to weaken a tooth by as much as 50 percent. Inlays and onlays are made of high-strength material bonded to the tooth, and that bonding can increase the tooth’s strength by as much as 75 percent. These restorations have been known to last 30 years and longer.

Filling, inlay, onlay or crown: which fits the damage?

The right restoration depends mostly on how much of the tooth is left and where the damage is.

• A small cavity. A tooth-colored composite filling, mixed to match your teeth and completed in a single visit, is usually enough. See when you need a dental filling.
• A larger cavity or a failing filling between the cusps. An inlay can replace it and restore strength without covering the cusps.
• Damage that includes one or more cusps. An onlay rebuilds the biting surface and holds the tooth together.
• A tooth that is extensively broken down, or has had a root canal. A porcelain crown covers and protects the whole tooth. At the practice, every tooth treated with a root canal is capped with a porcelain crown.

Not sure whether your tooth has crossed the line into crown territory? Read are you an ideal candidate for a dental crown?

Who is a good candidate for an inlay or onlay

You may be a good candidate if:

• You have a large, old or fractured filling in a back tooth that needs replacing.
• Decay or a break has damaged part of a tooth, but plenty of healthy structure remains.
• A cusp has chipped or cracked off.
• You want a tooth-colored repair instead of metal. The practice never uses amalgam, and gold inlays are available, but most patients prefer the more natural look of tooth-colored materials.
• You would rather keep as much of your natural tooth as possible.

Some teeth are better served by a crown, for example when damage is so extensive that little healthy tooth is left to bond to. Dr. Haywood examines the tooth with digital X-rays and intraoral cameras and explains the options before recommending anything.

How inlays and onlays are placed at the practice

Inlays, onlays and crowns are completed in two visits.

1. Remove the damaged structure. At the first visit, all damaged structure is removed from the tooth. If an old filling has fractured, it comes out along with any decay present.
2. Take an impression and place a temporary. An impression of the prepared tooth guides the making of your custom inlay or onlay. Before you leave, a temporary restoration is placed to protect the tooth until the follow-up appointment.
3. Bond, polish and check the fit. At the follow-up, Dr. Haywood removes the temporary and checks the new restoration for an ideal fit. Once it is approved, it is bonded to the tooth and polished to a natural sheen.

If dental work makes you anxious, laughing gas is breathed through a nasal mask and wears off quickly so you can drive yourself home, and oral conscious sedation is also available.

Caring for a tooth with an inlay or onlay

Between visits

A temporary restoration is not as strong as the final one. Avoid sticky foods such as caramel and chewing gum, and when flossing, pull the floss out the side instead of popping it up through the contact. If the temporary comes off, call the office during business hours.

After your final restoration

If you were numbed, avoid chewing and hot drinks until the numbness wears off, since it is easy to bite or burn your lip or tongue. Some sensitivity to hot, cold and pressure is normal. If the treated tooth seems to touch before your other teeth, call for an adjustment. The post-op instructions page has more detail.

For the long run

Brush twice a day, clean between your teeth daily and keep regular cleanings. The edges of any restoration can still decay if plaque is left there. If you grind your teeth, a custom bite guard can help protect your dental work.

Cost, insurance and financing

Every tooth is different, so your fee is set after Dr. Haywood examines it. The practice is out of network with all dental insurance companies. You pay at the time of your visit, and the office files the claim on your behalf so your plan can reimburse you for what it covers. Health savings and flex plans are welcome, and financing is available through CareCredit, with no-interest options up to 12 months, and Cherry, with plans from 3 to 24 months. See financing options.

Frequently asked questions

Is an onlay as strong as a crown?

Onlays are conservative compared with traditional crowns and equally strong, which is why they are preferred where possible.

Are inlays and onlays better than regular fillings?

For larger areas of damage, yes. Traditional fillings have been shown to weaken a tooth by as much as 50 percent, while bonded inlays and onlays can increase a tooth’s strength by as much as 75 percent. For small cavities, a composite filling is usually all that is needed.

Will anyone be able to see my inlay or onlay?

They are made from tooth-colored materials that match your teeth and are designed to be undetectable.

Can an old silver filling be replaced with an inlay or onlay?

Often, yes. Old amalgam is removed under rigorous safety protocols designed to minimize exposure to mercury vapor, and the tooth can then be restored with the most conservative tooth-colored option that fits the damage. See mercury-free dentistry.

Ask about a less invasive repair in Timonium

If you have been told you need a crown, or you have a large filling that is breaking down, find out whether an inlay or onlay could save more of your tooth. Request an appointment or call (410) 453-9399. The office of Dr. Steven W. Haywood, DDS is at 108 W Timonium Rd, Ste 200, Timonium, MD 21093. Learn more about inlays and onlays and all of the options in restorative dentistry.