Indirect dental restorations repair teeth with damage beyond what a simple filling can address. These custom-made components are fabricated outside the mouth, in a specialized laboratory or using advanced in-office milling technology. Once prepared, they are precisely fitted and bonded to the affected tooth, restoring its structure and function and integrating seamlessly with natural dentition.
Understanding Indirect Restorations
Indirect restorations differ from direct fillings, which are placed and hardened directly inside the mouth during a single appointment. Indirect restorations involve a multi-step process where the restorative material is manufactured externally. This external fabrication allows for greater control over the material’s properties and the restoration’s precise shape and fit. The prepared restoration is then permanently affixed to the tooth in a subsequent visit.
This indirect approach is particularly beneficial for larger areas of tooth decay or damage, where enhanced strength and a precise anatomical fit are required. The laboratory or milling machine environment enables the creation of restorations with superior durability and marginal integrity. This process ensures the restoration accurately mimics the original tooth structure, providing a durable and aesthetically pleasing repair.
Common Types of Indirect Restorations
Inlays: These indirect restorations repair damage located within the cusps, or chewing surfaces, of a tooth. They are custom-made to fit precisely into the prepared cavity, typically addressing decay or fractures that do not extend to the outer edges. An inlay restores the internal structure, providing strength and protection while maintaining much of the natural tooth material.
Onlays: Extending beyond the cusps, onlays cover one or more elevated chewing surfaces without encapsulating the entire tooth. They are chosen when a tooth has sustained more extensive damage than an inlay can address, but less than what would require a full crown. Onlays reinforce the tooth structure, preventing further fracture and effectively restoring the chewing surface.
Dental Crowns: Sometimes called caps, these are comprehensive restorations that cover the entire visible portion of a tooth above the gum line. A crown is indicated when a tooth has significant decay, extensive fractures, or has undergone root canal therapy, requiring complete protection and restoration of its shape and strength. Crowns provide full coverage, acting as a new outer layer for the damaged tooth.
Dental Bridges: These serve to replace one or more missing teeth by spanning the gap in the dental arch. They consist of artificial teeth, known as pontics, held in place by dental crowns placed on adjacent natural teeth or dental implants. Bridges restore chewing ability and maintain the alignment of remaining teeth, preventing them from shifting into the empty space.
Veneers: Thin, custom-fabricated shells designed to be bonded to the front surface of teeth. They are primarily used for cosmetic purposes, addressing issues such as discoloration, minor chips, uneven tooth alignment, or gaps between teeth. Veneers provide a natural-looking enhancement, transforming the appearance of the smile while preserving much of the underlying tooth structure.
The Placement Process
Receiving an indirect restoration typically involves at least two dental appointments. The initial visit prepares the affected tooth: decay or damaged structure is removed, and the tooth is shaped to receive the new restoration.
After preparation, an impression of the tooth and surrounding areas is taken, either with traditional materials or digital scanning, to create a precise model for the dental laboratory. A temporary restoration is then placed to protect the tooth while the permanent one is fabricated.
The impressions are sent to a dental laboratory, where technicians craft the custom restoration. This off-site process ensures precise fit and aesthetic qualities. Fabrication can take several days to a few weeks, depending on complexity and materials.
During the second appointment, the temporary restoration is removed, and the tooth is cleaned. The permanent restoration is tried in to ensure accurate fit, proper bite, and appearance. Once confirmed, it is permanently bonded or cemented to the tooth with dental adhesive.
Materials Used
Indirect restorations can be fabricated from a variety of materials, each offering distinct properties regarding strength, aesthetics, and durability.
Porcelain and Ceramic: Highly valued for their natural, tooth-like appearance, these are common choices for restorations in visible areas. They can be color-matched to surrounding teeth, providing an aesthetic outcome.
Zirconia: A ceramic material recognized for its exceptional strength and durability, suitable for restorations that endure significant chewing forces. Zirconia can be customized to match tooth shade, offering both functional resilience and aesthetic appeal.
Gold Alloys: Traditionally used for indirect restorations due to their superior durability, biocompatibility, and resistance to wear. Gold restorations are known for their longevity and precise fit, adapting well to the tooth structure. Their high strength makes them particularly effective for posterior teeth where chewing forces are greatest.
Lab-Made Composite Resin: A more durable alternative to direct composite fillings, fabricated under controlled laboratory conditions. This process enhances their strength and wear resistance compared to chairside composites. They offer good aesthetics and can be a suitable option for certain restorative situations, balancing durability with a natural appearance.
Porcelain-Fused-to-Metal (PFM): These restorations combine a strong metal substructure with an aesthetic porcelain outer layer. PFM crowns and bridges are a long-standing choice, balancing durability and aesthetics, though the metal can sometimes be visible at the gum line.
Longevity and Maintenance
The expected lifespan of indirect dental restorations can vary significantly, typically ranging from 5 to 15 years, and sometimes even longer. Factors influencing durability include the type of material used, the restoration’s location in the mouth, and the patient’s oral hygiene practices. Habits such as teeth grinding or clenching can also impact longevity.
Maintaining indirect restorations involves consistent and thorough oral hygiene, similar to caring for natural teeth. This includes brushing at least twice daily with a fluoride toothpaste and flossing once a day to remove plaque and food debris. Regular dental check-ups and professional cleanings are also important for monitoring the restoration’s condition. Avoiding habits like biting on hard objects or using teeth to open packages can help prevent damage and extend the life of the restoration.