Root canal infection: Symptoms and Treatments

A root canal infection is a debilitating oral condition that happens when bacteria invade the inner chamber of the teeth due to untreated dental decay or trauma. Patients with a root canal infection should seek treatment immediately because the infection can spread quickly once the bacteria attack the soft pulp material of the interior layer of the tooth. Root canal therapy is an effective treatment done to clean out the infected pulp and restore the tooth.

The human body can fight off oral infections very effectively. But there is no way in which it gets antibodies deep inside a tooth. This is where the dentist comes in. If you are experiencing any of the aforementioned symptoms, be sure to contact your dentist immediately. Do not ignore these signs. Your problems will just get worse. It's important to receive prompt and proper professional treatment. Not only will the root canal treatment eliminate your pain, but it will also get your tooth in good condition.

What Is a Root Canal?

First things first, let's see what root canal is. This term refers to two things. It can appertain to the dental procedure whereby the infected material is removed and toothache is relieved. But it can also relate to the inner part of the tooth that is between the tooth root and pulp. Each root canal contains blood vessels and nerves. Blood vessels deliver various nutrients to both nerves and teeth. As for the tooth's nerves, they have the ability to sense different influencing factors like pressure, heat, and cold. In the event of severe pulp infection and tooth decay, root canal treatment may include nerve removal as a necessary stage of the dental procedure.

Origins of root canal infection

Origins of root canal infection

While root canal causes vary, they all start the same way: with an injured tooth. Whether it’s a crack or chip in the tooth, a fractured tooth root, damage to the tooth pulp (with or without damage to the exterior of the tooth) or a tooth having repeated dental procedures, they can all lead to root canal system infections. However, the number one cause of root canal system infection is tooth decay.

Before causing a root canal system infection, the decay (a.k.a. cavity) must first develop beyond the tooth enamel, which is the hardest structure in your body—it’s even harder than bone! Factors such as the thickness and quality of the enamel can determine how long it takes for a cavity to form, but it is typically within months—which is why your dentist wants to see you bi-annually for checkups.

It’s when you don’t attend checkups that your tooth decay is likelier to penetrate through the enamel and into the next layer of the tooth—the dentin—that you become at risk of a root canal infection. Once the decay progresses through the dentin and reaches the tooth pulp, microorganisms in the tooth decay can cause inflammation, which promotes bacteria growth and the spread of infection.

causes of infection after a root canal 

causes of infection after a root canal

There are many reasons why a tooth can have an infection after a root canal. These include:

  • The shape of your root canals can be very complicated and areas of infection may go undetected in the first procedure.
  • Your tooth could have narrow or curved canals that weren’t fully cleaned and disinfected during the root canal.
  • Your tooth may also have extra, accessory canals that could be housing bacteria which may reinfect a tooth.
  • If the placement of the crown or permanent restoration is delayed following treatment, it could allow harmful bacteria back into your tooth.
  • Your tooth may get a new cavity after treatment, or become cracked or damaged, leading to a new root canal infection.

Can an infection spread to the gums or to other teeth?

Like any other infection, a root canal infection can spread to surrounding tissue in the mouth, including other teeth, gums, and tissue in the cheeks and face.

The infection won’t go away until it’s treated, and the longer you wait, the farther it can spread.

How far the infection spreads depends on how soon you get it treated after you start noticing symptoms. If you seek treatment hours or a couple of days after the infection starts, the spread can be minimized to the tooth itself or the surrounding teeth and tissues.

A root canal infection that’s left untreated can spread far beyond the tooth. In some cases, the infection can spread to the jaw, the face, and even into the bloodstream.

Warning signs

determining if a tooth requires root canal treatment is often a tricky task. Only qualified, highly experienced dentists can decide on the necessity of a procedure that involves root canal by use of professional methods.



Infected root canals cause acute pain as the inner tooth material is extremely sensitive. In some cases, the root canal infection has a tendency to thrive and give rise to a dental abscess. The tooth pain becomes unbearable and it must be treated promptly. Not all kinds of tooth pain are associated with a root canal, though. Just because you are experiencing strong tooth pain, that doesn't mean that you need a root canal therapy. Sometimes the tooth that requires a root canal doesn't hurt at all. Furthermore, tooth pain can be caused by other dental conditions, such as tooth decay, exposed dentin, periodontal disease, sinus infection, bruxism, and tooth fracture.The key is to determine the location, onset, duration, and character of the pain. It's critical to determine if the pain is dull or sharp and intense. The underlying condition can exist for weeks or even months, causing some kind of ache or discomfort. While most patients are capable of identifying which tooth actually hurts, the pain can be nondescript and vague in some cases. The following are types of pain that often indicate a root canal infection:

  • Severe tooth pain when chewing;
  • Pain that is so strong that you can't sleep at night.
  • A pain that occurs when you're putting pressure on the infected tooth;
  • Thermal stimuli pain - for instance, it may happen when you drink cold water right after a hot beverage, or vice versa;
  • A spontaneous pain that is either intermittent or continuous;
  • A lingering toothache;
  • A pulsing toothache.

 Tooth Discoloration

An individually darkened tooth that develops a dark yellow, blue or gray tone can be a sign of root canal infection. Luckily, such a tooth can be noticed with ease. It as a dark shade compared to the rest of teeth. The tooth changes colour because of the limited blood flow.   Tooth discoloration generally indicates pathological changes that take place in the nerve area. A dark-coloured tooth frequently means that your tooth nerve is badly infected. As the infection spreads, the nerve gets weak and dies eventually. The dead nerve must be treated as soon as possible. Otherwise, it's going to harbour bacteria that cause a variety of oral problems.

Gum Tenderness and Swelling

Gum Tenderness and Swelling

Swelling is another associated symptom. It comes in different types and forms. In some cases, it can look normal and is accompanied by gum tenderness. Other times there is a big lump you can easily see or feel. The swelling sometimes expands to the neck or face in extreme cases. It often goes hand in hand with a toothache. Similar to tooth pain, the swelling doesn't always indicate the infected root canals. This makes it difficult to determine the necessity of root canal surgery. Here are some swelling symptoms that may point to root canal infections:

  • Swelling that lasts for a long period of time;
  • A gum pimple-like boil situated in front of or on the root tip;
  • The tooth that feels a bit taller than adjacent teeth;
  • A recurring pimple that forms on the gums;
  • Pronounced swelling.

Dental abscess

A dental abscess occurs when the bacteria and dying pulp material create deep pockets full of pus around the tooth root. This causes severe unease and bad breathe and is visible via an enlarged or persistent red bump or pimple on the gum. A foul-smelling liquid may also start to seep out of the abscess.

A periodontist will drain the painful abscess during the root canal procedure and clean out the bacteria to alleviate the pain.

Chronic bad breath

Chronic bad breath

Patients suffering from root canal infection usually have chronic bad breath. If the bad breath is persistent despite brushing, flossing and using dental washes, then an infection is probably present.

The bacteria responsible for a root canal infection gives off an odor. This causes bad breath and a bitter taste in the mouth. The development of an abscess can further worsen the situation.

Treatment for root canal infection



Not all tooth infections require antibiotics. In some cases, your dentist may be able to drain the abscess. Other cases might require a root canal or removal of the infected tooth.

Antibiotics are generally used when:

  • your infection is severe
  • your infection has spread
  • you have a weakened immune system

The type of antibiotic you’ll need depends on the type of bacteria causing the infection. Different classes of antibiotics have different ways of attacking bacteria. Your dentist will want to choose an antibiotic that can effectively eliminate your infection.

Antibiotics of the penicillin class, such as penicillin and amoxicillin, are most commonly used to help treat tooth infections.

An antibiotic called metronidazole may be given for some types of bacterial infections. It’s sometimes prescribed with penicillin in order to cover a larger variety of bacterial species. While penicillin antibiotics are common used for tooth infections, many people are allergic to them. Make sure to tell your dentist about any allergic reactions you’ve had in the past to medications. If you’re allergic to penicillin, your dentist might a different antibiotic, such as clindamycin or erythromycin.

Root canal therapy

Root canal therapy

When all means of restoration and treatment fail, dentists suggest a root canal therapy to save the infected tooth. In fact, it is the last resort method to save a natural tooth that is on the verge of failure. The teeth will be cleaned thoroughly and disinfected. Local anesthesia will be administered to keep away pain and discomfort during the procedure.

An access hole will be made on the tooth to remove the infected pulp. Dental files of varying sizes will be inserted into the hole to scrub out any remaining residue from the walls. A jet of water will ensure all the debris is thoroughly removed. A small amount of medication will be placed in the tooth to avoid reinfection.

Since the nerves and blood vessels are removed from the tooth, it would lack the nutrition to support it. Hence, it could become weak and crumble when excessive stresses are applied to it. dentists suggest you get a crown to be placed on the tooth to hold it intact and functioning like normal.

Root canal retreatment

To treat a root canal infection, a root canal retreatment may be recommended to give your tooth a second chance. This retreatment is similar to the first root canal procedure.

In retreatment, your dentist or root canal specialist will typically do the following:

  • Look for infected or dead (necrotic) tissue around the area of the root canal and take an X-ray.
  • Numb the area around the affected tooth using local anesthesia.
  • Place a protective barrier around the tooth to protect your gums and mouth.
  • Use a dental drill to get through the filling and enamel to the pulp and root canal area.
  • Clean out the area where the tissue is infected or dead, and remove old root filler material or medicine that may have been in the root.
  • Dry out the area, then fill up the newly cleaned space with a safe, latex-based polymer filler (gutta-percha).
  • Use filling material, such as amalgam or composite, to protect the tooth and allow it to heal from the infection.
  • If necessary, carve away some of the outer enamel and place a permanent crownover the tooth to protect it from future infections.

Tips for preventing root canal infections

There are several things you can do to help prevent a root canal infection, which involves taking care of your teeth after the procedure:

  • Brush and flossat least twice a day.
  • Use a gentle, antiseptic mouthwashfor the first few days after a root canal. Use it as often as you’d like afterward, too.
  • Use an over-the-counter pain medicationlike ibuprofen for soreness after treatment.
  • Return to your dentist for a final crown or permanent restorationas soon as possible. This will seal the root canal from bacteria and protect your tooth.
  • Get dental cleanings at least twice a yearto keep your teeth generally healthy and catch decay or infections early.
  • See your dentist right awayif you notice any early signs of infection.