A cracked tooth is a common dental issue involving a line or fracture extending from the chewing surface into the tooth structure. This type of damage can range from a superficial, cosmetic flaw to a severe structural problem. Whether such a fracture can heal itself depends entirely on the tooth’s biological structure and the severity of the damage.
The Biological Limits of Tooth Repair
Unlike tissues such as bone or skin, the hard outer layers of a tooth cannot initiate a true self-repair process for a structural fracture. This limitation is due to the tooth’s unique composition. Enamel, the outermost layer, is non-living and contains no cells or blood vessels to facilitate regeneration.
The layer beneath, dentin, contains microscopic tubules but has minimal ability to repair structural damage. While teeth can undergo remineralization, this process is limited to repairing microscopic demineralization caused by early decay. Remineralization deposits calcium and phosphate ions back into the enamel, but it cannot fuse the two sides of a physical crack back together. If a crack extends into the dentin, the body forms a protective layer of reparative dentin within the pulp chamber, which does not address the crown’s structural integrity.
Categorizing Different Types of Tooth Cracks
Dentists classify fractures based on their location and depth, as the category dictates both the treatment and the tooth’s long-term outlook. Understanding these distinctions is crucial for determining the necessary intervention.
Craze lines are the most minor type, appearing as superficial hairline fractures confined entirely within the outer enamel layer. These lines are extremely common in adult teeth, usually asymptomatic, and pose no threat to the tooth’s health.
A fractured cusp involves a break in the pointed chewing surface, often occurring in teeth weakened by large existing fillings. This fracture typically does not extend to the pulp, and the tooth remains in two main pieces.
The true cracked tooth is a more serious concern, characterized by a vertical fracture that starts on the chewing surface and extends toward the root. This type often involves the sensitive inner pulp tissue, leading to pain and potential infection before the tooth separates into distinct fragments.
The most severe classification is the split tooth, usually resulting from an untreated cracked tooth. In this case, the fracture has progressed completely through the tooth, dividing it into two or more distinct, movable segments.
Recognizing Symptoms and Professional Diagnosis
The symptoms of a cracked tooth are often inconsistent, making self-diagnosis difficult. A distinct sign is erratic pain when biting down on food, which is frequently sharper and more intense upon the release of biting pressure. This “rebound pain” is caused by the fractured segments flexing apart under pressure and snapping back together when released. This movement stimulates the nerve endings in the pulp.
Sensitivity to temperature extremes, particularly cold, is another frequent symptom, sometimes lasting for a few seconds after the cold stimulus is removed. Because the pain can be subtle, dentists rely on specific diagnostic tools to confirm the crack’s presence and extent:
- Transillumination involves shining a high-intensity fiber optic light through the tooth structure. A crack blocks the light beam, creating a visible shadow line.
- A diagnostic bite test uses a small, hard instrument, such as a Tooth Sleuth, placed on individual cusps. Pain resulting from biting helps isolate the exact location of the fracture.
- Dentists may apply a staining dye to the tooth surface, which penetrates and highlights the fracture line under magnification.
- A narrow, localized pocket depth found during a periodontal probing can indicate that the crack has extended vertically down the side of the root.
Repairing a Cracked Tooth
Since a structural crack cannot heal naturally, professional intervention is necessary to stabilize the tooth and prevent the fracture from spreading. Treatment is proportional to the severity and depth of the crack.
For minor craze lines and small chips, the least invasive option is dental bonding, which uses a composite resin to fill the defect and restore the smooth surface.
For a fractured cusp or a structurally compromised cracked tooth, a full-coverage dental crown is the standard treatment. The crown holds the segments together, preventing the crack from flexing and propagating further down the root.
If the crack has reached the inner pulp tissue, causing irreversible inflammation or infection, a root canal procedure is performed first to remove the damaged pulp. This is immediately followed by placing a stabilizing crown.
A split tooth or a crack extending far below the gum line usually has a poor prognosis. In these severe, irreparable cases, the tooth must be extracted to prevent infection from spreading. Prompt professional evaluation is the only way to save a compromised tooth. Avoiding habits like chewing ice or using a mouthguard for nighttime grinding can help prevent future fractures.