A cracked tooth beneath a dental crown is a serious complication. Although the crown protects the tooth, the underlying structure remains vulnerable to biting forces and wear, which can lead to fractures. The possibility of saving the tooth depends entirely on the specific characteristics of the crack. This article explores how fractures are identified and the factors that determine if the tooth can be salvaged.
Identifying the Crack and Assessing Severity
A crack beneath a crown is usually suspected based on patient symptoms rather than visual inspection. Patients often report sharp, sudden pain when biting or chewing, especially when releasing the bite. Another common sign is lingering sensitivity to hot or cold temperatures, which suggests the fracture is irritating the dental pulp—the soft tissue containing the tooth’s nerves and blood vessels.
Diagnosing the crack is challenging because the crown obscures the tooth surface, making standard visual inspection inadequate. Dentists rely on a combination of diagnostic tools to confirm the fracture’s presence and extent. One technique involves having the patient bite down on a specific instrument to isolate the pain and pinpoint the crack’s location.
Specialized methods are used to visualize hidden damage. These include transillumination, where light is shined through the tooth to make the crack line visible. Staining the tooth with a dye after crown removal can also reveal fracture lines. While standard X-rays may show bone loss suggesting a vertical fracture, advanced imaging like Cone-Beam Computed Tomography (CBCT) provides a three-dimensional view. CBCT is effective at detecting the crack’s position and depth.
The most definitive assessment often requires removing the existing crown. Once the crown is off, the dentist can visually inspect the entire tooth surface using magnification. This inspection determines if the crack is superficial or extends deeper into the tooth structure. The severity and location of the crack directly dictate the tooth’s prognosis and the necessary treatment plan.
Key Factors Determining Tooth Salvageability
The possibility of saving the cracked tooth is determined by three characteristics: its location, depth, and direction. Cracks confined to the chewing surface that do not extend far below the gumline offer the best prognosis. These fractures, sometimes called fractured cusps, typically involve only the outer portions of the tooth structure.
The most significant factor affecting salvageability is whether the crack extends below the gum line and into the root. A crack that remains entirely supragingival (above the gum tissue) can often be stabilized and protected with a new restoration. Conversely, a fracture extending subgingivally, especially if it reaches the root surface or bone, is complex to treat. This complexity arises from the difficulty of sealing the area against bacteria.
A vertical root fracture (VRF) runs along the long axis of the tooth from the crown toward the root tip and is generally considered unsalvageable. This fracture allows bacteria to penetrate deep into the surrounding bone and ligament, leading to localized infection and bone loss. While multi-rooted teeth can sometimes be treated by removing the fractured root (hemisection), a VRF in a single-rooted tooth almost always requires extraction.
Involvement of the dental pulp also affects the prognosis. If the crack has exposed the pulp tissue to bacteria, an infection will develop, requiring root canal therapy to remove the infected tissue. Even after a root canal, the tooth’s long-term survival depends on whether the fracture can be structurally sealed to prevent re-infection.
Treatment Options for Saving the Tooth
When the crack is salvageable, the primary goal is to stabilize the fractured segments and prevent bacterial contamination. For minor, superficial cracks that have not affected the pulp, the dentist removes the old crown, seals the fracture with bonding material, and places a new, properly fitted crown. A new crown is necessary to physically hold the tooth segments together, preventing the crack from widening under chewing pressure.
If the crack has extended into the pulp tissue, causing irreversible inflammation or infection, root canal therapy is required before placing a new crown. This procedure involves cleaning out the infected pulp from the inside of the tooth and sealing the root canals. The root canal removes the source of infection and prepares the tooth for rebuilding.
Following root canal treatment, the tooth is restored with a core buildup and covered with a definitive crown for maximum protection. Placing a crown early on a cracked tooth improves the tooth’s long-term survival rate. The new crown distributes forces evenly across the tooth structure, preventing the crack from progressing further down the root.
Solutions When the Tooth Cannot Be Saved
When the fracture is a vertical root fracture or extends too far below the gum line, the tooth cannot be effectively sealed or saved. Extraction then becomes necessary. Delaying the removal of a fractured tooth risks spreading the infection to the jawbone and adjacent teeth. Extraction eliminates the source of infection and prepares the site for replacement.
Modern dentistry offers options for replacing a lost tooth to restore function and appearance. The most recommended solution is a dental implant, which involves surgically placing a titanium post into the jawbone to act as a root, topped by a custom crown. Implants offer superior stability and prevent the bone loss that occurs after a tooth is extracted.
Alternative replacement methods include a fixed dental bridge. This uses adjacent healthy teeth as anchors to support a prosthetic tooth spanning the gap. While effective, this option requires preparing neighboring teeth that are otherwise sound. Removable partial dentures provide a less permanent and more cost-effective solution for tooth replacement.