A cracked tooth often causes sharp, intermittent pain upon biting or chewing. The fracture introduces a pathway for oral bacteria to invade the sensitive inner tissues of the tooth, known as the pulp. Root canal treatment is designed to remove this infected or inflamed pulp, clean the internal canal system, and seal it to prevent reinfection. Whether this treatment can successfully save the tooth depends entirely on the location, depth, and direction of the fracture line.
Classifying Cracks: Determining Treatment Viability
The viability of saving a cracked tooth hinges on an accurate diagnosis of the fracture type. Craze lines are the most minor damage, appearing as superficial cracks confined to the outer enamel layer. These lines rarely cause symptoms and require only monitoring or simple cosmetic treatment. A fractured cusp involves the breaking off of a tooth’s chewing surface, often due to a large existing filling. If the fracture does not extend into the pulp chamber, a simple restoration suffices; otherwise, if the pulp is exposed or irreversibly damaged, root canal treatment becomes necessary.
The term “cracked tooth” refers to a fracture that begins on the chewing surface and extends vertically toward the root. This crack is the most common cause of cracked tooth syndrome symptoms, including pain upon release of biting pressure. A root canal may be viable if the fracture has not yet reached the pulp or if the pulp is only reversibly inflamed. The primary factor for restorability is that the crack remains above the gum line or does not extend significantly into the root structure.
A crack that progresses too far becomes a “split tooth,” extending completely through the crown and root, separating the tooth into two distinct segments. This condition is non-restorable because the pieces cannot be rejoined and sealed effectively. A vertical root fracture (VRF) begins in the root and travels upward toward the chewing surface, and these are almost always deemed unrestorable. Distinguishing between these classifications determines if the tooth can be saved.
The Purpose of Root Canal Therapy in Cracked Teeth
Root canal therapy (RCT) is required when a crack allows bacteria to penetrate the pulp, causing inflammation and infection. The purpose of the root canal is not to physically repair the crack, but to eliminate the biological consequence of the fracture.
The procedure involves creating an opening in the crown to access the infected pulp chamber. The endodontist cleans, shapes, and disinfects the internal canal system, removing all diseased tissue and bacteria. This process stops the pain and prevents the infection from spreading into the supporting bone. Stabilizing the tooth’s internal environment by removing the inflamed pulp is a prerequisite for further restorative work.
The clean canals are then filled with an inert, rubber-like material called gutta-percha, and sealed to prevent future bacterial ingress. This internal sealing is for the long-term health of the tooth, but it does not provide structural support to the cracked external structure. The root canal ensures the tooth is biologically sound, but a subsequent restoration is mandatory for mechanical reinforcement.
When Extraction Becomes the Only Option
Extraction is necessary when the fracture’s severity makes a successful seal or long-term structural integrity impossible. The two primary crack types necessitating extraction are the split tooth and the vertical root fracture (VRF). A split tooth, defined by the complete separation of the tooth into two or more fragments, cannot be saved because there is no reliable method to permanently bond the pieces and prevent leakage.
Vertical root fractures are problematic because they run lengthwise down the root, often occurring in teeth that have previously had a root canal. These fractures allow direct communication between the mouth and the bone, resulting in continuous bacterial contamination and an inflammatory response. The hallmark of a VRF is often a narrow, deep periodontal pocket localized to the site of the crack, indicating that the fracture has extended to the root surface below the gum line.
Extraction is the accepted treatment for VRFs and split teeth because the ability to seal the canal system is compromised. Attempts to save such teeth result in failure, persistent infection, and eventual bone loss. A deep periodontal pocket associated with the crack, often measuring five millimeters or more, decreases the success rate of any restorative treatment, making extraction the most predictable long-term solution.
Restoration and Long-Term Prognosis
Following a successful root canal procedure on a restorable cracked tooth, the next step is placing a full-coverage dental crown. This restoration is mandatory for preserving the tooth. The crown functions like a hoop, binding the remaining segments together and preventing the crack from propagating further down the root.
Delaying the placement of this full-coverage restoration increases the risk of the fracture worsening, potentially leading to a split tooth and eventual tooth loss. Studies indicate that a cracked tooth receiving timely root canal therapy and crown protection has a favorable long-term prognosis. Survival rates for such treated teeth are high, often 80 to over 90 percent after several years. This success rate depends on the crack being confined to the crown and not extending too far into the root structure.