Understanding Re-Root Canal Therapy or Endodontic Retreatment

What is a Root Canal?

Root canal treatment is used to remove infected pulp from within a tooth. Dental pulp contains the nerves and blood vessels in our teeth and can become infected due to the buildup of bacteria underneath the gum line due to injury or decay that comes with age. 

Pulp is located in canals that stretch from the crown to the root of your tooth, and root canal treatment goes into these canals to remove infected pulp, disinfect the tooth, and re-seal it. In theory, a root canal will remove the infection, reduce the chance of it reoccurring, and save the tooth from needing to be extracted.  

Understanding Tooth Structure 

Before we discuss endodontics anymore, it is a good idea to familiarise yourself with tooth structure so you know what parts of your teeth the procedure will affect. The structure of a tooth can be broken down into 2 parts, the crown and the root: 

• The crown is the visible part of the tooth, above the gum line 

• The root is the tooth’s anchor, which extends into the jaw and holds the tooth firmly in place. 

Teeth also contain several other elements that support their structure: 

• Enamel: A hard substance that coats and protects the crown 

• Cementum: A hard coating that protects the root 

• Dentine: A soft substance that forms most of the tooth 

• Dental pulp: The soft connective tissue within the tooth, made up of nerves and blood vessels

What is Endodontic Retreatment 

Root canal treatment is not always successful, and when the process fails, a re-root canal therapy (endodontic retreatment) is a necessary step. 

Endodontic retreatment aims to undo the original root canal therapy by reopening teeth, removing filling materials used to reseal the tooth, and disinfecting the inside of the tooth properly. After this, new filling materials are inserted, and the tooth is sealed again. 

If retreatment works, your tooth should be saved from extraction and further infections, as the original root canal therapy intended. 

When is Endodontic Retreatment Needed? 

There are several reasons why a re-root canal therapy may be necessary, some more obvious than others: 

• Saliva contamination: If the root canal is not sealed properly after the procedure, or isolated during it, bacteria from saliva can re-contaminate the canals within the tooth and lead to infection. 

• Uncleaned canals: The canal systems within teeth are unique, and many people have narrow, curved, or hard-to-access accessory canals. When this is the case, a dentist may not sufficiently clean the tooth, leaving infected pulp inside.  

• New cavities: Unfortunately, teeth that have undergone root canal therapy can still get cavities. These cavities can cause infection and make re-rooting treatment necessary. 

• Broken/unfinished restoration: If the protective crown is installed after a root canal breaks – or is not installed at all – bacteria can re-enter the tooth and cause an infection.  

As some of these signs may be hard to spot, it may not always be immediately obvious when you need endodontic retreatment. If you experience pain when biting, a toothache, a gum boil, or a foul taste in your mouth after a root canal therapy, you should contact your dentist as these could be signs you need retreatment. 

Endodontic Retreatment Procedure  

The Endodontic retreatment procedure will be largely the same as your initial root canal therapy, but instead of removing just tooth pulp, your dentist will remove the previously inserted tooth and root canal fillings and any remaining pulp (if necessary).  The re-root canal procedure can be broken down into several steps, these are: 

1. Examination: Before beginning any dental procedures, your dentist will examine the infected tooth using an X-ray and determine the cause and extent of damage within your tooth. 

2. Administration of anaesthetic: As a root canal therapy can be painful, your dentist will administer a local anaesthetic to limit discomfort and pain. 

3. Accessing the tooth: The dental crown placed on top of your tooth during your previous root canal treatment is removed so your dentist can access your tooth canals. 

4. Disinfection: Previous root canals filling material is removed by your dentist as well as any remaining pulp. The tooth is then thoroughly examined using radiographs and thoroughly disinfected.  

5. Re-sealing: Teeth canals are refilled, typically with a material called gutta-percha, but this can vary. This should prevent any bacteria from building up within the tooth as well.  

6. Restoration: Finally, a new dental crown will be placed on the top of your tooth, sealing it completely.  

Endodontic retreatment may not always be possible, especially if the canals within your teeth are particularly narrow or difficult to access. In cases where re-root canal therapies are not possible, your dentist may recommend endodontic surgery. The most common type of endodontic surgery is apicoectomy, where the dentist goes into the gum near the tooth root to remove the infected tissue. 

Endodontic Retreatment Recovery  

Root canal recovery will vary from person to person, and based on your dental history and the procedure you have undergone, your dentist will give you tailored advice on how best to recover. There are a few general tips worth implementing in your daily routine post root canal, and these include: 

• Avoid harsh tooth brushing on the affected tooth. 

• Contact your dentist if you feel severe pain or see any discharge from the site of the procedure. 

• Avoid particularly hot, cold, or spicy foods for the initial days after a root canal therapy, as the tooth and gum are likely to be sensitive.  

Recovery from root canal therapy can be made easier by OTC pain medication. Ask your dentist about whether this is applicable after your procedure has finished.   

When is Endodontic Retreatment not applicable? 

Though endodontic retreatment can be an effective way to save a tooth from extraction, there are instances where re-root canal therapy is not applicable: 

• Large cracks. A cracked tooth is a common reason for infections of root canals. When there is a large fracture in the root, however, a root canal or re-root canal is not always possible as the integrity of the tooth is too low, and re-sealing it may be impossible. 

• Compromised tooth health: If the affected tooth is damaged past a certain point, it is unlikely that your dentist will advise a re-root canal. 

• Calcified tooth canals: Canals within the tooth can become calcified and impossible to access, meaning a root canal cannot be performed. 

Effectiveness of Endodontic Retreatment  

Endodontic retreatment is regarded as generally successful by most professionals, with a long-term success rate estimated to be as high as 88%.  

When recovering from the procedure, the maintenance of good oral care is vital. Taking care to brush your teeth and keep your mouth (and the site of the procedure) as clean as possible will give you the best chance of long-term success.  

Make sure to attend dental checkups regularly, and at the sign of intense pain, discharge, or excess swelling, contact your dentist immediately. Though it is not the only reason a re-root canal therapy can fail, poor oral hygiene can lead to infections and potentially the need for tooth extraction. 

Elevate Your Post-Treatment Care 

After endodontic retreatment, maintaining excellent oral hygiene is more important than ever. A consistent, gentle, and effective oral care routine helps support healing and protects against future complications.  

That’s why Oral-B is committed to promoting the value of daily oral care — and the Oral-B iO Series electric toothbrushes lead the way. Powered by revolutionary magnetic iO technology, the iO Series delivers a effective clean that’s both thorough and kind to sensitive areas, making it ideal for post treatment care. With real-time feedback and intelligent features, it helps users stay on track with brushing habits that truly make a difference. 

But good oral health doesn’t stop at home - regular dental check-ups remain essential to monitor progress and catch any issues early. By combining dentist and dental hygienist visits with an elevated brushing experience from the Oral-B iO Series, you’re giving your mouth the best support possible, every day.