Why Is My Root Canal Tooth Hurting After Years? Causes Explained

Root canal therapy carried step by step eliminates the pain associated with a decayed tooth. The dentist drills a cavity to clean the root canal and covers the cavity with filling materials. Further, they restore the tooth structure using dental crowns. Typically, getting a root canal treatment eliminates pain and sensitivity. This is because the dentist removes the infected pulp and bacteria during the procedure. And the removal of infection relieves the pain. The treatment, when carried out properly, has a high success rate. Nearly 9 out of 10 root canal-treated teeth survive for 8-10 years.^[1] However, in rare cases, a root-canaled tooth hurts after years, causing throbbing pain and discomfort. Scroll further to know how it feels.

Symptoms of Failed Root Canal Years Later

A failed root canal, or a root canal-treated tooth that caught infection, indeed shows the symptoms of tooth decay. These include:

• Sharp sensitivity to cold or hot foods associated with throbbing pain.
• Persisting pain when you chew or apply bite force.
• Gum swelling, along with soreness.
• Small boils or pimples on the gums may also ooze out pus.

Having one or a combination of these signs indicates something isn’t right and requires retreatment. However, your dentist will confirm the exact underlying cause. They conduct a physical examination followed by the x-rays and pulp vitality test. This is to understand the condition of the tooth interior and the surrounding bone condition. 

In case you are wondering what could be the reasons for a failed root canal, the following section is of help.

How Can a Tooth Get Infected Years After a Root Canal?

A root canal-treated tooth can catch an infection under any of the following circumstances. 

Inadequate Cleaning

Although rare, in some cases, dentists may miss cleaning the complex curved or hidden canals. This leaves behind bacteria or infected pulp inside the canal. These conditions have a greater incidence of reinfection and apply to the curved root canals in the molars.^[2] 

Delayed Permanent Restoration

After treatment, the dentist applies a temporary sealant to cover the cleaned root canals. This sealant prevents bacteria and food from reentering the canals until the permanent crowns are fixed. However, the chances of cleaned root canals getting reinfected are high due to unexpected delays in getting crowns or permanent fillings. 

Improper Oral Hygiene

Maintaining a healthy oral cavity is essential to prevent infections. Adherence to basic oral health tips like brushing and flossing can prevent cavity formation. Failing to do so can be the reason your root canal tooth feels weird months later. Bacteria or plaques may accumulate on the treated tooth, eventually leading to cavities and reinfection. 

Leaked or Faulty Sealant 

Failed sealant due to insufficient thickness or improper placement of filling materials leaves space. This allows the bacteria in the saliva to get under the filling material. It multiplies in number, causing reinfection. 

Cracked or Broken Crown

Poor dental material used for crowns or biting on hard objects can cause cracks or breaks in dental crowns. Oral bacteria enter these minute crevices and develop cavities, reaching deeper inside the tooth surface infecting the interiors. 

Suppose you experience mild pain in the root canal-treated tooth. In case you’re doubtful if that is a sign of root canal infection or not, the following section is of help. We elaborated on the difference between healing and reinfection for a better understanding. 

Had a Root Canal Tooth Still Hurts: How Long Do I Wait To Know It's Reinfected?

Most root canal reinfections manifest just within one or two weeks. Ineffective cleaning, leaky sealant, or delays in dental restoration causing the reinfection are manifested early on. However, it can take a few months or a year for the tooth to develop new cavities or the crowns to break. Note that high-quality dental crowns are durable and can last for years. Subpar-quality crowns do not last longer and can break. This can be a reason why a tooth with root canal hurts years later treatment. But this isn’t your case. You recently underwent the root canal treatment, and the tooth still hurts. The possible reasons for this can be pretty different. Understand this in detail by scrolling down.

Why Does My Tooth That Had a Root Canal Still Hurt? A Brief Note on Reinfection and Healing!

While a decayed tooth causes throbbing pain and sensitivity, it should fade away after root canal therapy. The bacteria in the cavities cause pulp inflammation. This inflamed pulp poses pressure on the surrounding nerves and tooth structure, causing immense pain. During root canal treatment, dentists remove the pulp and clean the canals, so you should feel relieved from pain after treatment. In some cases, the pain lasts for a few days. This is particularly true when the surrounding inflamed gums or tissues experience discomfort due to treatment or instrument. Note that this minor discomfort relieves off in a few days and you should feel normal within a week after the procedure. However, you should consider it serious when the pain is persistent and growing severe. That could be a sign of inadequate cleaning or nerve damage, which requires dentist attention. Don’t hesitate to consult your dentist. 

Why Does My Root Canal Tooth Hurts When I Bite Down? Does It Need Specialist Attention?

A root canal-treated tooth still hurting a few weeks, months, or a year later is a sign of reinfection. It needs specialist attention as the infection can cause abscesses and pus formation with severe pain and discomfort. Further, it may spread to other body parts and, in some cases, can lead to jawbone loss. Its always recommended to see your dentist before the infection worsens. 

What Does a Dentist Do if the Tooth With Root Canal Hurts With Pressure?

The dentist will first examine your oral cavity and confirm the reinfection. They adopt any of the following measures to clear infection. 

• Retreatment: The dentist will reopen the filling material or crown to gain access to the decayed portion. They will clean the canals and carefully examine the interior structures under magnification. Using magnifiers and illumination will help dentists better understand the canal obstruction or curvatures. In most cases, obstructed or curved root canals can be the primary cause of reinfection. They will seal the open tooth structure using filling material and restoration. 
• Root tip extraction: The unusual root canals need special attention. Dentists perform endodontic surgery for narrow or obstructed root canals. They use advanced technology like digital imaging or operating microscopes to perform root tip extraction or apicoectomy. It is also called root-end resection or removal of the inflamed root portion. The dentist opens the gums under local anesthesia to visualize the bottom bony area. They will remove the inflamed root and seal it using a filling material. Next, they will close the incisions using sutures and allow the gums to heal. Within a few months, the jawbone around the surgical spot will heal, allowing you to feel normal. Most candidates resume normal life in a very short period.
• Tooth extraction: Tooth removal is the last resort and is preferred only in cases of severe infection. Root canal retreatment procedures typically aim to save the tooth structure. However, the infected tooth is removed to stop the spread of infection to the surrounding oral tissues. A tooth extraction is followed by replacing the space with a bridge or implant.   

Dentists prescribe antibiotics during either of these treatments to control the infection and prevent its spread. While it may seem overwhelming to get endodontic surgery for root canal reinfection, it is indeed necessary to prevent the spread of infection. What if we say these unnecessary circumstances are avoidable with simple measures? In fact, it’s true! Scroll down to learn more about the effective preventive measures. 

Steps To Prevent Root Canal Tooth Reinfection

Reduce the chances of root canal reinfection by adopting the following measures. 

1. Proper oral hygiene: Compromised oral hygiene is the primary cause of dental infection. Decays and caries on the root canal-treated tooth can be prevented by following basic dental care. Brush your teeth twice regularly and floss your teeth, or use an interdental cleaner to clean your teeth. Use fluoride toothpaste, as it strengthens the tooth enamel. ^[3] 
2. Routine dental checkups: Do not skip dental checkups. Visit your dentist for scheduled cleanings and plaque removal. Early detection prevents infection from spreading, saving your teeth and other oral tissues.
3. Save the restoration: While maintaining oral hygiene, watch what you eat. Stick to a diet that safeguards the dental filling or crown. Avoid sticky foods like jams, candies, and jellies. Limit sugar intake and avoid soft drinks and soda. Do not bite on hard foods or chew objects like pencils, ice, or nuts and crackers. This can harm the restorations, such as crowns, causing chips or cracks. 
4. See a reliable dental professional: Improper cleaning is indeed the main cause of a failed root canal. Qualified and experienced dentists or endodontists can diagnose the problem effectively. Getting treated by random professionals, particularly those without enough expertise or appropriate tools, increases the risk of complications due to incomplete cleaning or inappropriate sealing. Choose trustworthy dental professionals by verifying their credentials and qualifications. Rely on referrals and ex-patient testimonials to gain confidence.  

Are you worried about making the right choice for your dental work? At Envoy Health, we partner with top-rated dental professionals after a thorough vetting process. If you're uncertain about your current treatment plan or experiencing lingering issues, getting a second opinion can provide clarity and peace of mind. A trusted expert can confirm the diagnosis, suggest alternative solutions, and help you avoid unnecessary risks. 

With Envoy Health, you’re not just choosing a provider — you’re choosing confidence in your care. Sign up with our platform, and let us hold your hand as you receive the highest standard of care.

References 

1. How it is performed: Root canal treatment
2. Successful Individualized Endodontic Treatment Of Severely Curved Root Canals In A Mandibular Second Molar: A Case Report
3. Oral Hygiene