When I’m taking a patient’s medical history and he/she mentions having had a root canal procedure, I take note — especially if the patient has a chronic illness that began weeks to months after the procedure. There is a growing concern among holistic health-care professionals that root canal procedures are making people sick. Reason: Bacteria and other microbes can live on in the treated tooth and release toxic by-products that damage the immune system, leading to all kinds of health problems. Infection also can occur years after the procedure if the sealant material on the tooth breaks down.

The irony of this: The main function of root canal (technically known as endodontic therapy) is to enable people to avoid having a tooth extracted because it is infected, cracked or decayed. But I have seen many cases in which fatigue, weak immunity or a chronic illness, including sinusitis, fibromyalgia or an autoimmune condition such as rheumatoid arthritis, sets in after root canal. Some doctors think that there even may be a link between root canal and increased cancer risk.

More than 20 million root canal procedures are performed annually in the US. Not all root canal procedures go wrong. Many procedures save teeth that have been damaged by trauma, for instance, or when an infection is treated early. But not all root canal procedures are harmless either. To find out how you can protect yourself, our editors spoke to Tom McGuire, DDS, a leading authority on mercury-safe, holistic dentistry in Sebastopol, California (www.DentalWellness4U.com).

Here’s what you need to know…


Root canal is a way to “save” the bony shell of the tooth while removing the infected living tissue inside it. During the procedure, the dentist removes the pulp, which is the tissue, including nerves and blood vessels, in the center of the tooth, and the tissue in the roots. The tooth is then cleaned and sealed.

When you understand what is going on inside a tooth, you understand why bacteria can be a problem. Within the inner layer of a tooth’s enamel coating are millions of microscopically small canals called tubules that transport nourishing fluid throughout the dentin (the area between the pulp and the enamel coating). During a root canal procedure, the main root canal area is packed with a filling material, but the tubules are too small to fill. As a result, bacteria often remain inside the tubules after the tooth is sealed up, out of reach of antibiotics or immune system antibodies.

A key variable is the individual’s own immune system. If yours is strong, then you can probably tolerate a chronic, low-level flow of toxic bacteria into your system without any noticeable ill effects. Over time, as people age and experience declines in immune function, it becomes harder for the body to handle this toxic stress.

What can go wrong: The infection can progress to the bone surrounding the root tips. There is a big difference between bacteria contained within a tooth and bacteria in bone, which has its own blood supply. Now the infection is not contained within the tooth but is in the body.

The body may be able to wall this off and form a protective cyst, but the body’s own bacteria fighters can get access to the cyst or infection only on its outer edges, leaving the bacteria with a safe haven to produce virulent toxins. If the body cannot maintain control of the cyst and it breaks or leaks, the blood supply will receive a massive dose of highly toxic bacteria. This can dramatically affect the overall health of someone with an already compromised immune system.

Microorganisms that can cause chronic infection after a root canal procedure include enterococci, streptococci, peptostreptococci and candida, among others. Some people feel pain from the remaining living nerves in the affected area or the nerves of the jawbone from a developing abscess, but not all do.

At this point, even if the root canal procedure has been done correctly, the only way to treat the existing infection in the bone is to have the tooth extracted and the infected area cleaned. Once the infection has been eliminated, the onslaught on the immune system stops and healing begins.


As Dr. McGuire does, I advise patients who need to have a root canal procedure about the possible risks and urge them to make sure that a root canal procedure is really what they need. Many root canal procedures shouldn’t be done in the first place. Several other oral health issues, such as chronic mercury poisoning from amalgam fillings and gum disease, can severely weaken the immune system. Impaired immunity makes it harder for these patients to fight off infection. These oral health issues should not be overlooked when deciding if a root canal should be performed. I also advise patients about the option of having the tooth extracted and replaced with a metal-free bridge.

If you do choose to have a root canal, it is best to have the treatment done by a root canal specialist (endodontist) who is willing to take as long as needed to give repeated antimicrobial treatments if necessary.

The reality, however, is that no endodontist can tell for sure whether all the bacteria is gone.

Endodontists may perform follow-up X-rays to see how the tooth is healing. If the infection worsens, it will dissolve bone in that area — and this will show up on an X-ray.

If you’ve already had a root canal treatment, monitor your health carefully, especially if other infection-related illnesses occur and don’t respond to treatment. That may be the main way to know if you have this type of festering infection. A blood test can reveal chronically low white blood cells, another indication of this type of infection.

If you suspect that you have a health problem caused by a root canal procedure, the tooth can be retreated by an endodontist or you can have the treated tooth extracted. I’ve had many patients whose conditions clear up as soon as the tooth is extracted.