A dental crown, often called a “cap,” is a custom restoration designed to fully encase the entire visible portion of a natural tooth. Its primary function is to restore the tooth’s original form, size, and strength. This process also improves the tooth’s appearance. A crown provides comprehensive protection and structural support for a compromised or weakened dental structure when damage is too significant for a simple filling to offer long-term stability.
Protecting Compromised Teeth
A crown becomes necessary when a tooth suffers damage so extensive that its structural integrity is compromised. This occurs with severe dental decay where the resulting cavity is too large for a traditional filling to support the remaining tooth walls. Dentists often recommend a full-coverage crown when a restoration would exceed approximately two-thirds of the tooth’s width. Placing a large filling in such a tooth can create a wedging effect under chewing pressure, increasing the risk of catastrophic fracture.
Teeth that are fractured or severely cracked also require the full external support a crown provides. While minor chips can be repaired with bonding, a crown is required for a crack extending into the underlying dentin to prevent propagation. The crown physically binds the fractured segments together to withstand chewing forces. Without this external bracing, the tooth is susceptible to splitting, often necessitating extraction.
Extreme wear from chronic teeth grinding (bruxism) can deplete enamel and dentin, flattening cusps and reducing tooth length. Crowns rebuild the lost tooth material and restore the proper biting surface, protecting the pulp from exposure. Furthermore, crowns are utilized for cosmetic modification, such as covering a misshapen tooth or masking severe discoloration that does not respond to whitening treatments.
Restoring Teeth After Major Procedures
A common indication for a crown is protecting a tooth following a root canal treatment. The preparation of the internal access cavity and removal of the pulp chamber roof significantly reduce reinforcing tooth tissue. The loss of the tooth’s internal blood supply also leads to a decrease in moisture content. These factors combine to make the tooth structurally weaker and more susceptible to fracture.
A crown provides the necessary cuspal coverage and external reinforcement to prevent the tooth from splitting. This is especially important in premolars and molars, which bear heavy chewing loads.
Crowns are essential anchoring components for a fixed dental bridge used to replace missing teeth. The crown is placed over the adjacent natural tooth or dental implant, known as an abutment. This secures the artificial tooth (pontic) in position. The crown’s full coverage is critical for biomechanical stability, ensuring the abutment teeth withstand the additional forces from supporting the bridge structure.
When Crowns Are Not the Right Solution
A full-coverage crown is a definitive restoration that requires the removal of significant healthy tooth structure, so conservative options are preferred when viable. For small areas of decay or minor chips, a direct dental filling remains the standard treatment. Fillings are placed directly into the prepared cavity, preserving the maximum amount of natural tooth material. They are sufficient when the cavity is shallow and does not compromise the structural cusps.
When damage is too large for a standard filling but does not warrant a crown, a partial-coverage restoration is the preferred, conservative alternative. These options are known as inlays and onlays, which are fabricated in a dental laboratory and bonded into or onto the tooth. An inlay is used when the decay is confined within the cusps of the biting surface.
An onlay is a more extensive restoration, sometimes called a partial crown, chosen when the damage extends to cover and protect one or more cusps. The distinction between a full crown and an onlay hinges on whether the cusps are structurally sound enough to be preserved. By covering only the damaged portions, inlays and onlays reinforce the tooth while conserving more healthy enamel and dentin than the aggressive reduction required for a complete crown.