Dental inlays and onlays offer an excellent alternative to “direct” amalgam or composite fillings to restore teeth that have sustained some damage, but not enough to require a full coverage crown. While “direct” fillings such as dental amalgam and composite fillings are placed immediately after the decay or damage is removed and the tooth is prepared, inlays and onlays are known as “indirect” fillings. This means that they are fabricated outside of the mouth prior to final bonding or cementation.
While in the past, many inlays and onlays were caste from gold; today’s dental inlays and onlays are typically custom made of either the highest grade of dental porcelain or composite resins. In addition to providing an exact match to the color of tooth for a cosmetically pleasing result, inlays and onlays have the distinct advantages of being more durable than other fillings, preserving more underlying tooth structure and actually strengthening the tooth so that it can bear up to 50 to 75 percent more chewing forces.
Inlays and onlays only differ from each other in the amount of tooth structure they cover. An inlay is fabricated when the replacement of tooth structure does not require coverage of any cusp tips. If the damage from decay or injury is more extensive and involves more of the tooth’s chewing surface, including one or more cusp tips, an onlay is required.
Both inlays and onlays are fabricated outside of the mouth based upon the exact specifications provided by an impression of the prepared tooth. The final inlay or onlay is then custom made by either a dental laboratory or in-office with a same day system.
Inlays and onlays are indirect restorations designed to repair teeth with damage that is too extensive for a simple filling but does not require a full crown. An inlay fits within the cusps of a back tooth to restore the central chewing surface, while an onlay extends over one or more cusps when additional coverage is needed. These restorations are fabricated from strong, tooth-colored materials and are bonded to the prepared tooth for a precise fit.
Because they replace only the damaged portion of the tooth, inlays and onlays preserve more natural structure than crowns and often provide a more conservative long-term solution. The off-site fabrication process, whether at a dental laboratory or via an in-office milling unit, allows for excellent contouring and marginal accuracy. Many patients choose these restorations for their combination of strength, longevity and esthetics.
Fillings are placed directly into a prepared cavity and are best for small to moderate areas of decay, while crowns cover the entire visible portion of a tooth and are used when a tooth is heavily damaged. In contrast, inlays and onlays are indirect restorations that are custom-made to fit the prepared area, offering a level of precision and fit that direct fillings cannot match. They occupy the middle ground between fillings and crowns by conserving healthy tooth structure while providing greater strength than a large filling.
The decision among a filling, an inlay/onlay, or a crown depends on the amount of remaining tooth structure, the location of the tooth, and functional demands such as chewing forces. The dentist evaluates these factors during a clinical exam and may use imaging or digital scans to help determine the most conservative and durable option. When used appropriately, inlays and onlays can extend the life of a compromised tooth while maintaining a natural appearance.
The process begins with a comprehensive evaluation that includes a visual exam and radiographs or digital imaging as needed to assess decay, cracks and overall tooth structure. During treatment, the dentist removes any decay or weakened material and shapes the preparation for an accurate fit, then captures impressions or digital scans of the prepared tooth. Depending on the chosen workflow, the restoration is either milled in-office for same-day placement or sent to a dental laboratory for fabrication.
When a laboratory is used, a temporary restoration may be placed while the custom piece is created to protect the tooth and maintain function. At the placement visit the dentist checks fit, occlusion and shade, then bonds the restoration using adhesive techniques that create a durable union with the tooth. Final adjustments are made to ensure comfortable chewing and a natural bite before you leave the office.
Common materials for inlays and onlays include porcelain and advanced ceramics such as lithium disilicate, which are prized for their esthetic properties and strength. These materials mimic the optical qualities of natural enamel, resist staining and provide reliable wear characteristics in the mouth. In some cases, composite resin or metal alloys have been used, but ceramic restorations are generally preferred for their color stability and biocompatibility.
The material chosen depends on the tooth's location, the amount of chewing force it will bear and the patient’s esthetic goals. Reinforced ceramics offer excellent fracture resistance for back teeth, while highly esthetic porcelains can be matched precisely for visible restorations. Your dentist will recommend the material that best balances longevity, function and appearance for your specific situation.
Ideal candidates are patients with moderate tooth damage from decay, large failing fillings or small fractures that are not extensive enough to require a crown. Candidates should have reasonably healthy surrounding gum and bone tissue, and any active decay or periodontal issues should be addressed before a restoration is placed. Patients who prioritize conserving natural tooth structure and prefer a metal-free, natural-looking restoration often benefit from inlays and onlays.
People who habitually grind or clench their teeth may still receive inlays or onlays, but the dentist will assess functional risk and may recommend protective measures such as a night guard. Final candidacy is determined by a clinical examination and discussion of restorative goals, and the treatment plan is tailored to preserve tooth structure while ensuring durable function. When in doubt, the dentist can explain alternatives like crowns and why they might be recommended in more severe cases.
Yes, many practices use chairside CAD/CAM systems to design and mill ceramic inlays and onlays during a single appointment, allowing for same-day restorations. This workflow eliminates the need for a temporary restoration and speeds treatment by producing a custom-fit piece while you wait. When a laboratory fabrication is selected, the process typically requires two visits—one for preparation and impressions and another for final bonding once the restoration returns from the lab.
Not every case is suitable for same-day milling; complex occlusal relationships, shade matching or multiple-unit cases may still be sent to a skilled laboratory for optimal results. Your dentist will explain the recommended workflow based on clinical needs and the goal of achieving a precise, long-lasting restoration. Both approaches aim to deliver excellent fit, function and appearance.
The lifespan of an inlay or onlay depends on factors such as the material used, the patient’s oral hygiene, chewing habits and the quality of the initial placement. Ceramic restorations placed with modern bonding techniques can provide many years of reliable function, often lasting a decade or longer when properly maintained. Regular dental checkups allow the dentist to monitor the restoration for wear, marginal breakdown or recurrent decay and address issues early.
Habits such as bruxism, chewing hard foods or poor oral hygiene can shorten the longevity of any restoration, so protective measures and preventive care are important. If signs of wear, rough margins or sensitivity develop, prompt evaluation can often preserve the underlying tooth and allow for repair or replacement before more extensive treatment is necessary. With attentive care, many patients enjoy long-term esthetic and functional benefits from their restorations.
Daily oral hygiene remains the foundation of long-term success for inlays and onlays, so brush twice daily with fluoride toothpaste and clean between teeth once a day using floss or interdental cleaners. Avoid using teeth to open packages or bite very hard objects, particularly during the first days after bonding while the restoration fully stabilizes. Attend routine dental visits so the dentist can evaluate the restoration, check margins and make minor adjustments if needed.
If you experience unusual sensitivity, roughness, or a change in your bite after placement, contact the dental office for an assessment rather than waiting for the next scheduled checkup. In patients who clench or grind, a custom night guard can protect the restoration and surrounding teeth from excessive force. Proactive care and prompt attention to changes can significantly extend the life of the restoration.
Bruxism increases functional stress on any dental restoration and can raise the risk of fracture or wear for inlays and onlays, so the dentist carefully evaluates grinding habits before treatment. If bruxism is present, material choice and restoration design can be adjusted to improve strength, and occlusal adjustments can help distribute forces more evenly. In many cases, inlays and onlays remain viable options when combined with protective strategies.
Common protective measures include fabrication of a custom night guard to reduce nighttime grinding and counseling about daytime clenching behaviors. The dentist may also recommend monitoring and periodic maintenance to detect early signs of wear. With appropriate risk management, patients who grind their teeth can often still benefit from the conservative advantages of inlays and onlays.
A consultation with a dentist is the best way to determine whether an inlay or onlay suits your needs; the evaluation typically includes a visual exam, radiographs or digital scans and a discussion of functional and esthetic goals. The dentist will assess the extent of existing damage, the condition of surrounding tissues and any risk factors such as bruxism that might influence material selection or treatment planning. Based on that assessment, the dentist will recommend the most conservative, durable option tailored to your case.
Contemporary Dentistry offers modern digital diagnostics and conservative restorative approaches that help inform this decision and create a personalized plan. If you are considering a restorative option that preserves tooth structure while improving function and appearance, schedule a consultation to review the findings and next steps. The result should be a clear recommendation aligned with your oral health goals and lifestyle.