A dental crown is a custom-made cap designed to fit entirely over a natural tooth that has sustained damage, decay, or significant wear. This restoration completely covers the visible portion of the tooth, from the gum line upward. By fully encasing the tooth, the crown restores its original shape, size, and strength, providing a protective shield that allows the compromised structure beneath to remain functional.
Specific Clinical Situations Requiring Restoration
A dental crown is necessary when a tooth’s structural integrity is severely compromised and cannot be restored with a simpler procedure. This occurs when a tooth has suffered extensive decay or fracture, leaving less than half of the original structure intact. In these cases, a traditional filling lacks enough remaining material to bond to and would be prone to failure under chewing forces.
Protecting a tooth following root canal therapy is a common indication for a crown. After a root canal, the tooth often becomes brittle because the internal structure is no longer vital. The crown reinforces the weakened structure, distributing biting forces and preventing the tooth from cracking.
Crowns are also used for repairing teeth with severe cracks or fractures, especially when the damage involves the biting surfaces. Without full coverage, these cracks can propagate, potentially leading to tooth loss. Furthermore, teeth severely worn down from grinding (bruxism) or erosion require the strength provided by a crown to re-establish proper bite function.
Finally, a crown is the standard component placed on top of a dental implant, serving as the functional and aesthetic replacement for a missing tooth. Crowns are also used as anchors to support a dental bridge, covering the natural teeth adjacent to a gap to hold the prosthetic teeth in place.
How Crowns Differ From Other Restorations
The primary distinction between a crown and other common restorations like fillings, inlays, and onlays lies in the extent of tooth coverage. A dental crown is a full-coverage restoration, completely covering all five surfaces of the prepared tooth above the gum line. This total encapsulation is necessary when the tooth has lost a significant amount of its original structure and requires maximum protection and reinforcement.
In contrast, a traditional filling is used for smaller areas of decay and is molded directly into the tooth. Inlays and onlays are partial-coverage restorations fabricated indirectly in a lab and then bonded to the tooth. An inlay fills the space between the cusps, which are the raised points on the biting surface.
An onlay is larger than an inlay, extending to cover one or more cusps, but it does not fully cover the entire tooth. These partial restorations are utilized when the damage is too extensive for a filling, but enough healthy tooth structure remains that a full crown, which requires more removal of healthy enamel, is unnecessary.
Material Options for Dental Crowns
The materials used to fabricate dental crowns offer different balances between aesthetics and durability. Porcelain or all-ceramic crowns are valued for their ability to mimic the natural color of tooth enamel, making them the preferred choice for front teeth. However, all-ceramic materials may be more susceptible to chipping or fracture under heavy biting forces compared to metal options.
Metal alloy crowns, which can include gold or base metals, are known for their exceptional strength and resistance to wear. These crowns rarely chip and require minimal removal of the natural tooth structure during preparation, making them a durable option often reserved for less visible back molars. Their main drawback is the metallic appearance.
Porcelain-Fused-to-Metal (PFM) crowns provide a compromise, featuring a metal substructure for strength covered by porcelain. PFM crowns offer better aesthetics than all-metal, but they can sometimes show a dark metallic line at the gum margin. Zirconia, a modern all-ceramic material, has become popular due to its high strength and excellent aesthetic properties. Zirconia is highly fracture-resistant and is often considered a standard for both front and back teeth.
Maintaining Your Crown and Expected Lifespan
The lifespan of a dental crown ranges from 5 to 15 years, though many can last longer with ideal care. Longevity depends on the crown material, the patient’s oral hygiene, and the stress the crown endures. Metal crowns tend to be the most durable, while all-ceramic options may be more prone to chipping.
Proper home care is necessary to maximize the crown’s lifespan. This involves brushing twice daily, paying attention to the area where the crown meets the gum line. Daily flossing is also required to remove plaque and food particles that accumulate around the margin. Patients should avoid habits such as chewing on ice or hard candies, as these actions can cause the crown to chip or loosen.
Regular dental check-ups allow a professional to monitor the crown for signs of wear or mechanical issues. Signs that a crown may need replacement include persistent pain, visible chipping, or a noticeable gap forming between the crown and the gum line. Addressing these issues promptly supports the long-term success of the restoration.