Failed Root Canal: Causes, Symptoms & Retreatment Options

Root canal therapy has a success rate of over 95%, saving millions of natural teeth each year. Still, like any medical procedure, it isn’t foolproof. Sometimes a treated tooth doesn’t heal properly or becomes infected again. This is known as a failed root canal or reinfected root canal.

At Ballantyne Endodontics, our mission is to help patients understand why root canals sometimes fail, recognize the symptoms, and explore treatment options that can save their natural teeth.

Why Do Root Canals Fail?

Root canals are highly successful, but a small percentage may fail due to:

• Complex Anatomy – Tiny canals or hidden branches can be missed.
  
• Residual Bacteria – If infection wasn’t fully removed, it can resurface.
  
• New Decay – Decay around a crown or filling may let bacteria back inside.
  
• Fractures or Cracks – Damaged teeth allow bacteria to penetrate.
  
• Delayed Restoration – If the crown or filling isn’t placed quickly after treatment, reinfection risk increases.
  
• Patient Factors – Poor oral hygiene or trauma to the tooth can compromise long-term success.

Symptoms of a Failed or Reinfected Root Canal

Common signs that a root canal may need retreatment include:

• Persistent pain when chewing or biting
  
• Lingering sensitivity to hot or cold
  
• Swelling, tenderness, or drainage near the tooth
  
• Gum “pimple” or abscess near the root
  
• Loose or damaged crown/filling
  
• Bad taste or odor in the mouth
  
• Tooth discoloration

Reinfection may occur weeks, months, or even years after the initial treatment.

Treatment Options for Failed Root Canals

1. Root Canal Retreatment

The most common solution is retreatment. The endodontist reopens the tooth, removes the old filling material, cleans and disinfects the canals, then reseals them. With modern imaging and tools, success rates are higher than ever.

2. Apicoectomy (Endodontic Surgery)

If retreatment alone isn’t sufficient, an apicoectomy may be performed. This microsurgical procedure removes the root tip and surrounding infected tissue, then seals the canals to prevent reinfection.

3. Antibiotics (Supportive, Not Standalone)

Antibiotics may be prescribed to help manage infection, but they cannot resolve the problem alone. They are typically used alongside retreatment or surgery.

4. Tooth Extraction (Last Resort)

When the tooth can’t be saved, extraction may be necessary. Restorative solutions like dental implants or bridges can replace the missing tooth.

Preventing Root Canal Failure

• Have the procedure completed by an experienced endodontist.
  
• Place the permanent crown promptly after treatment.
  
• Maintain strong daily oral hygiene.
  
• Visit your dentist regularly for exams.
  
• Protect teeth from cracks or trauma with custom mouthguards if needed.

Why Choose Ballantyne Endodontics?

Our specialists perform root canals and retreatments every day — far more than general dentists. We use advanced technology like CBCT 3D imaging and microsurgical techniques to locate hidden canals, identify infection, and save natural teeth.

Our compassionate approach and expertise in complex cases give patients renewed confidence and lasting relief.

FAQs About Failed Root Canals

How common is root canal failure?
Studies show success rates between 86% and 98%. About 5–10% of root canals may need retreatment.

Is retreatment painful?
With modern anesthetics, retreatment feels similar to the original procedure and is generally no more uncomfortable.

Can a failed root canal heal on its own?
No — untreated reinfection can spread and worsen. Retreatment or surgery is required to save the tooth.

How long will retreatment last?
With proper care and restoration, retreatment can be just as long-lasting as the original root canal.

When should I see an endodontist?
If you have pain, swelling, or other symptoms after a root canal, schedule an evaluation with a specialist.

Conclusion

A failed root canal doesn’t always mean losing your tooth. With advanced retreatment options, most reinfected teeth can be successfully saved.

Contact Ballantyne Endodontics today to schedule a consultation and learn about your treatment options.