Dental Inlays and Onlays: What They Are and When They’re Needed

Tooth damage is a common dental issue that many people experience due to decay, cracks, or wear. While small cavities can be restored with simple fillings and severely damaged teeth may need crowns, there is an important middle-ground solution: dental inlays and onlays. These restorations are designed to repair moderate tooth damage in a way that is strong, long-lasting, and preserves more of your natural tooth structure.

What Are Dental Inlays and Onlays?

Dental inlays and onlays are custom-made restorations used to repair damaged or decayed teeth. They are often called “indirect fillings” because, unlike traditional fillings placed directly in the mouth, they are fabricated in a dental lab and then bonded to the tooth.

Dental Inlays

An inlay fits within the grooves (cusps) of the tooth. It is used when the damage is too large for a filling but not extensive enough to require a crown.

Dental Onlays

An onlay covers one or more cusps of the tooth and sometimes the entire biting surface. It is also known as a partial crown and is used when the damage affects a larger portion of the tooth.

Common Materials Used:

• Porcelain

• Zirconia

• Composite resin

• Gold (less common today)

Porcelain and zirconia are especially popular because they blend naturally with tooth color and are highly durable.

How Inlays and Onlays Work: The Procedure Explained

The procedure for getting an inlay or onlay usually involves two visits but may be completed in a single session with advanced CAD/CAM technology.

Step 1: Examination and Diagnosis

The dentist examines the tooth using X-rays to determine the extent of decay or damage. If the structure is too weak for a filling but strong enough to avoid a crown, an inlay or onlay is recommended.

Step 2: Tooth Preparation

The damaged portion of the tooth is removed, and the area is shaped to ensure a precise fit for the restoration. The dentist takes impressions or digital scans of the tooth.

Step 3: Temporary Filling

A temporary restoration is placed to protect the tooth while the permanent inlay or onlay is being fabricated in the lab.

Step 4: Fabrication in Dental Laboratory

Highly skilled technicians create the restoration based on digital impressions to ensure a perfect fit, shape, and color match.

Step 5: Fitting and Bonding

During the second visit, the temporary filling is removed, and the inlay or onlay is carefully bonded to the tooth using strong dental cement.

Step 6: Polishing and Bite Adjustment

The dentist checks your bite, makes necessary adjustments, and polishes the restoration for a smooth and natural finish.

With proper care, inlays and onlays can last 10–20 years or more.

Benefits of Dental Inlays and Onlays

Inlays and onlays offer several advantages over traditional fillings and even full dental crowns.

a. Superior Strength and Durability

Inlays and onlays are made from materials like porcelain and zirconia, which are much stronger than standard composite fillings. This makes them ideal for teeth used for heavy chewing, like molars.

b. Preserve More Natural Tooth Structure

Unlike crowns, which require significant tooth reduction, inlays and onlays remove only the damaged portion, keeping most of the healthy tooth intact.

c. Excellent Fit and Natural Appearance

Because they are custom-made, inlays and onlays fit perfectly and blend seamlessly with natural teeth.

d. Resistant to Staining and Wear

Porcelain inlays and onlays are highly resistant to staining, making them a good cosmetic option.

e. Long-Lasting Solution

They last longer than traditional fillings and provide better protection against future decay.

f. Prevent Further Tooth Damage

They strengthen the tooth structure, reducing the risk of cracks and fractures in the future.

Overall, they provide a durable, aesthetic, and minimally invasive solution for moderate tooth damage.

When Are Inlays and Onlays Needed?

Dentists recommend inlays and onlays in several situations where the tooth damage is too extensive for a simple filling but not severe enough to require a crown.

a. Large Cavities

When decay is too wide or deep for a filling to hold, an inlay or onlay is used for better strength and support.

b. Cracked or Fractured Teeth

Minor cracks that don’t require a crown can be restored effectively with an onlay.

c. Replacement of Large, Old Fillings

If existing fillings are worn out or leaking, they can be replaced with more durable inlays or onlays.

d. Teeth with Weakened Structure

When too much tooth enamel is lost, but the root and walls are still strong, an onlay helps restore bite function without excessive removal.

e. Cosmetic Improvements

They can also be used to improve the shape or color of a damaged tooth for aesthetic enhancement.

When a Crown Is Needed Instead

If the tooth is severely weakened, has extensive cracks, or requires full coverage, a crown is a better option.

Understanding the extent of the tooth damage helps determine the appropriate type of restoration.

Aftercare and Long-Term Maintenance

Proper care ensures that dental inlays and onlays last for many years.

Daily Oral Hygiene

• Brush twice daily with fluoride toothpaste

• Floss around the restoration to prevent plaque buildup

• Rinse with an antibacterial mouthwash

Avoid Habits That Damage Teeth

• Avoid biting hard foods like ice or bones

• Don’t use teeth as tools (opening packets)

• Reduce habits like grinding or clenching

Regular Dental Check-Ups

Dentists check the restoration for wear and ensure the tooth remains healthy underneath.

Managing Sensitivity

Some patients experience mild sensitivity after placement, which usually resolves in a few days.

Protective Night Guard (if needed)

Patients who grind their teeth at night should wear a night guard to prevent stress on the restoration.

With proper care, inlays and onlays can function just like natural teeth and maintain their appearance for years.

Conclusion

Dental inlays and onlays provide a strong, aesthetic, and long-lasting solution for restoring moderately damaged teeth. They fill the gap between simple fillings and full crowns, offering a minimally invasive approach that preserves healthy tooth structure while delivering superior durability. Whether you have a large cavity, worn-out filling, or a cracked tooth, inlays and onlays can restore function and appearance effectively.

Information Courtesy

This information is based on insights provided by Dr Madhu, the lead dentist at Aditya Dental Care, 3rd Floor, KHM Block, 2nd Cross, 2nd Main Rd, Ganganagar, RT Nagar, Bengaluru, Karnataka 560032 Dr Madhu specializes in Microscopic Dentistry procedures, including professional Dental Implant and Kid Dentistry, and is known for her patient-centered approach and clinical expertise.