Root canals have a very high success rate as they help to save patient’s natural teeth that may have been affected by severe decay, injury or infection. Occasionally however root canals can fail. This can occur if bacteria get left in the complicated internal structure of the tooth or if bacteria enters the root system months or years later.

By identifying the symptoms of a failed pulp therapy treatment, and knowing what causes them, you can quickly treat the issue and save your natural tooth.

Can Root Canals Fail? Risks, Causes and Warning Signs for Patient

While the success rate of pulp therapy treatment is high, sometimes the complicated structure of the tooth can mean that the tooth becomes re-infected.

• Late failure – The root canal can fail shortly after treatment or can be a late failure and not cause any issues until months or years down the line.
• Early identification – If identified early then an pulp therapy specialist can quickly treat the issue to save the natural root of your tooth.
• Bacteria – Root canals failing are caused by bacteria getting into or remaining in the root canal system.

Why Do Root Canals Fail? Common Causes and Risk Factors Explained

Understanding why root canals can fail means you know the importance of choosing experienced professionals to carry out your treatment.

• Complicated anatomy – Many teeth have narrow, extra canals or very curved canals making it difficult to identify. This can leave some of the infected pulp undetected.
• Waiting too long to fit a permanent crown – If you wait too long to fit a permanent crown this can allow saliva and bacteria to enter the canals.
• Leaky crown – If cracks form in the enamel, your fillings break or your cement deteriorates this can cause leaks and allow new bacteria to enter.
• Not fully cleaned – Sometimes there can be complicated lateral canals close to the tip of the root. These can be very difficult to clean due to the bacteria being hard to reach.
• New trauma or decay – New trauma or decay can occur to the edge of the crown and expose the inner fillings.

Failed Root Canal Symptoms: Warning Signs You Should Not Ignore

A failed root canal doesn’t always cause extreme pain, in many cases the infection will slowly develop. However you may notice:

• Constant or recurring pain – Pain in the tooth that is constant or comes back after months. Pain may be a dull throbbing pain, sharp pain when biting or constant aching.
• Sharp pain when eating hot or cold items suggests something has gone wrong with the tooth, since no nerves should remain.
• Swollen and tender gums – Swelling, redness and/or tenderness around the tip of the root.
• Pimple on the gum – A pimple on the gum can often leak nasty tasting fluid or pus. This is a clear sign of chronic infection at the tip of the root.
• Tooth discoloration – The tooth may darken or turn dull. This can indicate that the tissues inside have broken down.
• Loose tooth – The jawbone can become softened due to bacteria toxins and cause the tooth to feel loose.
• If you think you may have had a failed root canal then an pulp therapy doctor will use specialist equipment to accurately identify infection.

How Pulp Therapy Doctor Diagnose a Failed Root Canal and Find Infections?

• 3D CBCT scans – Advanced 3D scans can show any hidden canals, micro cracks and bone loss around the root tip.
• Digital x-rays – Digital x-rays can clearly show any changes in bone density around the tip of the root. This will also show how well your current natural rubber has sealed.
• Periodontal probing – This identifies how deep the pockets in your gums are around the tooth. We can rule out vertical fractures.
• High-powered dentistry microscopes will let the pulp therapy team inspect the tooth’s access hole to see if canals were missed.

Non-Surgical Root Canal Re treatment: Steps, Benefits and Outcomes

Dentists can resolve most root canal failures with non-surgical re-treatment.

• Removing restorations – The pulp therapy doctor will remove your crown, build up and access filling.
• The pulp therapy specialist will use special tools and solvents to remove the old natural rubber and seal.
• The pulp therapy specialist will locate any canals that were missed using 3D imaging. They will shape the canals and thoroughly clean using advanced antibacterial solutions.
• The specialist will seal the canals tightly after cleaning and drying. The pulp therapy specialist will fit a new permanent crown.

Root Surgery: When Pulp Therapy Specialist Microsurgery May Be Needed Explained

If non-surgical re-treatment isn’t possible due to blocked canals, broken instruments or chronic infection at the tip of the root then an root surgery can be performed.

• Small incision – A small incision will be made in the gums.
• Cutting tip – The pulp therapy specialist will remove the infected tip of the root along with any inflamed tissue or cyst.
• The pulp therapy specialist will place a small seal at the end of the root.
• The dentist will bring the gums together, and the jaw bone and tissues will heal over the coming months.

Tooth Extraction and Replacement After an Unsuccessful Root Canal

If a vertical fracture or bone loss caused root canal failure, the dentist will extract the tooth.

• If the tooth has a deep vertical fracture or significant damage below the bone line, the dentist cannot save it.
• A dentist will place a titanium implant into the jawbone to replace the root of the tooth. Dentists place a bespoke porcelain crown on the implant.
• Dental bridges – An alternative method of replacing the tooth. This will anchor the false tooth to healthy teeth either side.

Important things to do if you think you have a failed root canal.

1. Book in to see a specialist doctor. If you experience any constant pain, swelling or sensitivity then book in.
2. Get a 3D CBCT scan. This will accurately show where any missed canals, cracks or bone loss are.
3. Don’t ignore any pimple on your gums. This can indicate infection.
4. Ask about non-surgical re-treatment. This should be your first choice of treatment to save your natural root.
5. Avoid eating anything hard or sticky on the affected side.
6. Make sure you have your permanent crown fitted as soon as possible.

Failed Root Canal FAQs: Answers to Common Questions for Patients

How long can a root canal fail?

A root canal can fail at any time. If the dentist fails to clean the root canal or the temporary filling leaks, it may fail soon after treatment. Or it can fail years later due to new decay, fractures or deterioration of the seal.

Does root canal re-treatment hurt?

No! Root canal re-treatment isn’t painful. The dentist will numb the tooth, gums, and jaw with local chemicals. You may feel some mild discomfort after treatment, but you can easily control it with an over-the-counter anti-inflammatory.

Can a failed root canal make me ill?

Yes. If you do not treat the root canal and bacteria spread beyond the root, infection can reach surrounding tissues and the bloodstream. This can cause localized abscesses, inflammation, swollen face and increased risk for those with a weakened immune system.

What is the success rate of root canal re-treatment?

Non-surgical root canal re-treatment has a very high success rate. It can be anywhere between 75% and 85%. The outcome depends on the cause of the failure, on root fractures, and on how quickly we can clean and permanently crown the tooth.