A root canal procedure saves a tooth by removing infected or damaged pulp, the soft tissue inside its root. This treatment cleans and seals the tooth’s interior to prevent further infection and restore its function. While generally successful, a treated tooth sometimes doesn’t heal properly or becomes reinfected, leading to discomfort.
Recognizing the Signs
A failed root canal often presents with noticeable symptoms, indicating the initial treatment did not fully resolve the problem. One common sign is persistent or recurring pain in the treated tooth, which can manifest as a dull ache, a sharp sensation when biting down, or a throbbing feeling.
Sensitivity to hot or cold temperatures can also signal a problem. Swelling or tenderness in the gum tissue around the affected tooth is another indicator, sometimes accompanied by sensitivity to touch. A more distinct sign is pus discharge or a “pimple-like” bump (fistula or sinus tract) on the gum near the tooth, indicating an underlying infection. The tooth itself might also appear discolored, often darkening or turning gray, which can point to internal damage.
Reasons for Failure
Root canals can fail for several reasons, often related to the initial procedure or subsequent issues. One common cause is incomplete cleaning or sealing of the root canal system during the initial treatment. This can happen if tiny, complex, or extra canals are missed, allowing bacteria to remain and multiply. If these hidden canals are not thoroughly cleaned and sealed, residual bacteria can lead to persistent infection.
New tooth decay can also develop on the treated tooth, creating new pathways for bacteria to re-enter. A tooth might also sustain a new fracture or crack after the procedure, which can allow bacteria to leak into the treated area. A new infection can arise or a persistent infection from the original procedure can flare up, leading to symptoms months or even years later. Issues with the final restoration, such as a leaky crown, can also compromise the seal and allow bacteria to contaminate the tooth.
Confirming the Issue
A dental professional diagnoses a failed root canal through a combination of clinical examination and specialized imaging. During a clinical examination, the dentist inspects the tooth and surrounding gum tissue for swelling, redness, or a fistula. They may also palpate the area and tap on the tooth to assess tenderness.
Dental X-rays are a primary diagnostic tool, providing insights into the tooth’s internal structure and the surrounding bone. Periapical radiographs offer detailed two-dimensional views of the tooth root and the bone around it. For more complex cases, 3D imaging techniques like Cone Beam Computed Tomography (CBCT) can provide a comprehensive view, helping to identify missed canals, fractures, or persistent infections that might not be visible on conventional X-rays. The dentist also discusses the patient’s symptoms, combining this information with the examination and imaging findings to confirm the diagnosis and determine the extent of the problem.
Addressing a Failed Root Canal
Once a failed root canal is confirmed, several treatment options are available to address the issue. Non-surgical retreatment is often the first approach, involving re-opening the tooth to access the root canal system. Existing filling materials are removed, the canals are thoroughly re-cleaned to eliminate infection, and then re-sealed with new materials. This method has a high success rate and is frequently recommended.
When non-surgical retreatment is not feasible or successful, surgical retreatment, such as an apicoectomy, may be considered. An apicoectomy involves a small surgical procedure where the tip of the tooth’s root is accessed through the gum, removed, and the end of the root canal is sealed. If other options are not viable due to extensive damage or persistent infection, extraction of the affected tooth may be the only solution. Following extraction, options like a dental implant or bridge can be discussed to replace the missing tooth.