The Focal Infection Theory
By George E. Meinig D.D.S., F.A.C.D.
Most everyone involved in endodontics is familiar with the *Root Cause* documentary. The movie is based on The Focal Infection Theory, a concept that is not only over 100 years old but has also been debunked by scientific research as far back as the 1930s. Despite this, it is not the first time this theory has caused a stir during our careers, and we’re certain it won’t be the last.
We thought we’d revisit the last time this theory gained some traction in the dental community, which was in 1994 when a book titled *Root Canal Cover-Up* was published by Dr. George Meinig, a founding member of the American Association of Endodontists. The book included an introduction by Dr. Edwin Van Valey, a past president of the association. Dr. Meinig’s book is based on the research of Dr. Weston Price, conducted over 100 years ago using outdated methods from an era when the medical community had a limited understanding of immunology and infection. Consequently, the validity of Dr. Price’s conclusions has been disproved by many subsequent investigations.
Dr. Weston Price, a proponent of the focal infection theory, was once the Director of the National Dental Association, a precursor to the American Dental Association. This theory had a devastating impact on dental care at the time, leading to the widespread extraction of millions of teeth in a misguided effort to cure numerous ailments. The extraction of teeth was erroneously thought to be a treatment for a range of conditions including heart and eye infections, kidney and bladder problems, ovarian and testicular diseases, hyperactivity, depression, and arthritis.
Contrary to claims made in Dr. Meinig’s book, there has been no “Cover-Up” of Dr. Price’s research. Rather, it has become a non-issue for the medical and dental communities due to advances in science. Dr. Meinig asserted that his book is exposing the cover-up facts will point out how bacteria trapped in dental tubules can escape and be transported to another organ, gland, or body tissue where they start a whole new infection. However, extensive research and clinical experience have consistently demonstrated that endodontic therapy is safe and effective, with medical and dental studies continuing to validate these findings.
It is important to clear up some misconceptions about endodontically treated teeth. A tooth that has undergone root canal therapy is not a “dead” tooth. It maintains a relationship with the surrounding tissues, and the tooth’s life depends on the attachment apparatus to the jawbone rather than the integrity of the pulp. If a root canal-treated tooth were truly “dead,” it would be rejected by the body, as the body does not tolerate dead tissue. Most root canal-treated teeth are not infected, although some may be. Infection only occurs when microorganisms provoke a reaction, like how the skin is covered with microorganisms but remains uninfected under normal circumstances due to a functioning immune system. The presence of bacteria does not necessarily indicate an infection.
Clinical studies comparing individuals with extensive dental work, including root canal-treated teeth, to those without have found no difference in the likelihood of developing various diseases. Other studies, which involved extracting teeth from patients with rheumatoid arthritis, concluded that there was no benefit from the removal. Microscopic examinations have shown that the bone around successfully treated abscessed teeth usually heals without any evidence of infection.
Interestingly, a disclaimer in fine print at the beginning of Dr. Meinig’s book warns readers that “Readers of the information and material contained in this book should keep in mind that the various degenerative diseases that were found to take place during these studies (Dr. Price’s) also commonly arise from infections, other than those around teeth, and are also commonly due to nutritional deficiencies and/or excesses and to the wide range of biomechanical individuality that exists.” In the vast majority of cases, there is absolutely no modern evidence to support the claim that endodontically treated teeth serve as a focus of infection. Rather, teeth treated appropriately with modern conventional endodontic therapy have a very high success rate (90 to 95%), preventing unnecessary tooth loss and leading to healthy, functional, and aesthetic outcomes.
The American Dental Association’s Division of Scientific Affairs believes that endodontic treatment performed by qualified clinicians does not cause systemic disease.