NatDent

Root Canal

Within each natural tooth, there is a formation of soft tissue referred to as dental pulp; it contains nerves, arteries, veins, and lymph vessels If you were to look at a cross section of a tooth, the exterior surface of the crown is the enamel, followed by a tissue called “dentin.” Dentin is the bone-like tissue that supports the enamel and makes up most of the tooth structure. Within the dentin, lies the dental pulp tissue. The pulp extends from a pulp chamber in the crown of the tooth (that portion of the tooth visible above the gums) down to the tip of the root, being contained in what is referred to as the “root canal.” Although teeth can have more than one root, molars for example have two or three roots with root canals in each root, all teeth have only one pulp chamber.

In the early part of this century, when a tooth would become diseased or the dental pulp was injured, the accepted treatment was to extract the tooth. However, beginning in the late 1950′s teeth with infected or injured dental pulp were being successfully saved using a procedure called endodontics, or root canal therapy. There is little question that the public’s acceptance of endodontic treatment is on the rise. In 1969, for example, it was estimated that six million root canal fillings were being done each year. That number has now risen to about twenty?five million and by the year 2000, it is estimated that 30 million root canals will be filled annually.

What Happens When the Pulp is Damaged?

When the pulp is diseased or injured. your body will attempt to repair and heal itself. However, if it is unable to repair the diseased or injured pulp, the pulp dies. This is normally caused by bacteria gaining access to the pulp chamber, either through a fractured tooth or a deep cavity which can expose the pulp to the bacteria found in your own saliva. The presence of bacteria in the pulp causes an infection inside the tooth. Left untreated, this infection can abscess, (a buildup of infectious material (pus) at the root tip), eventually causing the pulp to die and the supporting bone surrounding the tooth will be destroyed.

What Does Root Canal Therapy Involve?

Root canal therapy involves the various procedures used by the endodontist (root canal specialist) or dentist to save the tooth from having to be pulled, by removing the infected or diseased pulp from the tooth. In simple terms, the pulp chamber and root canal(s) of the tooth are cleaned, sterilized, and sealed to prevent re-contamination of the root canal system. Although the treated tooth is no longer vital (you won’t be able to feel pain, hot, or cold, etc.) you have achieved several advantages:

The tooth was not removed leaving an empty space, which if left empty would cause teeth next to or opposite the empty space to begin shifting from their normal position. Shifting can cause teeth to become crooked or crowded, causing alignment problems that may eventually result in even more teeth being lost.
Your natural tooth has been retained maintaining the normal cosmetic appearance of your teeth.
Eliminates the need to have a replacement tooth (bridge) put in place of the removed tooth. Bridges are normally expensive and may also require extensive work on adjacent teeth for retention of the bridge.

Basic Concerns of the Patient

Individuals undergoing root canal therapy for the first time usually have great apprehension and many concerns: Is the procedure painful? Will this tooth have to be extracted later? How long will the tooth last? Will it turn black? Normally the procedure is painless as your dentist will use local anesthesia prior to starting to work on the tooth. Most restored teeth will last as long as your natural vital teeth. The reason for this is that as long as the root(s) of the endodontically treated tooth are properly nourished by the surrounding tissues, your tooth will remain healthy. It is somewhat of a paradox in that the average person thinks that a root canaled tooth is a dead tooth. However, it is not a “dead tooth” as long as the roots of the tooth are embedded in healthy surrounding tissues that bathe the external surface and offer it nutrition. For this same reason, it is seldom that a tooth will turn black. If appearance does become a prime concern, the tooth may be bleached or veneered (having a porcelain or composite facing placed over it). Most often, retention of the tooth and bleaching, veneering, or crowning are preferable to extraction and replacement with a prosthetic appliance (artificial tooth).

The Focal Infection Theory

Although there exists a great deal of controversy regarding the success of endodontic therapy, the scientific facts at the present time are that only about 10% of root canal treated teeth experience some type of failure. The controversy over endodontic treatment is not new. Beginning in about 1912, there was wide acceptance of the theory of “focal infection” which resulted in the wholesale extraction of both vital and pulpless teeth. It wasn’t until well after World War II, with the availability of improved x-rays, anesthetics, new methods and products, and the publication of the first major text book devoted to “Root Canal Therapy” that the “focal infection” theory lost favor and “saving” rather than extracting the tooth became the “standard of care.” Now however, the 1990′s has seen a resurrection of the focal infection theory.

Lets look briefly at the “Focal Infection” theory. The main purpose of the dental pulp is to supply nutrients to the dentin as long as the tooth is alive. This is done through microscopic tubules in the dentin. To give you some indication of what is meant by microscopic, each tooth contains approximately 1.5 million tubules. As the living cells necrose (rot) within the central pulp chamber of an infected tooth, this same phenomenon is happening within the tubules. In theory, root canal therapy attempts to completely obliterate and fill the main pulp chamber and canals. However, it is impossible to fill the millions of microscopic tubules. Once inside the tooth bacteria can remain within the tubules growing, and multiplying. Because microbes can change their form and function in response to a changed microenvironment within the tubules, they can go on living in spite of the altered oxygen and food supply. As they do so, they begin to produce various toxic chemicals, which have been shown to be harmful, sometimes being especially toxic to specific organs or organ systems. This phenomenon was confirmed in a recent 1987 study by Tronstad and associates demonstrating that anaerobic bacteria (bacteria not requiring oxygen to survive) were able to survive and maintain an infectious disease in periapical lesions of non?vital teeth. In a 1991 follow up study of endodontically treated teeth, these authors recovered microorganisms from periapical lesions of all examined teeth.

The immediate question this raises is: If there are bacteria present from every endodontically treated tooth, why doesn’t every root canal treated tooth become abscessed and fail? An oversimplification of the answer is that your own body’s immune system is able to contain and neutralize the bacteria.

Dr. Weston Price, during the early 1900′s, devoted most of his brilliant career to investigation of the focal infection theory. His research, involving thousands of patients and rabbits, formed the basis for the over 220 articles and 3 major books which he authored. In essence, the focal infection theory researched by Dr. Price holds that it is not the bacteria that causes systemic problems, but rather the toxic chemicals produced from the necrosis and decay within the tubules, whether the tooth had been endodontically treated or not. As a consequence of the fact that there was no way to completely seal the apex (tip of the root) and the tubules, the need to extract both vital and pulpless teeth, when an infection was evident, became the effective treatment.

There are now a group of dentists around the country who are openly advocating the extraction of every root canaled tooth on the basis of the research done by Dr. Price. This is certainly a radical approach to solving a problem that appears to be limited to only about 10% of the total number of root canal treatments done. Furthermore, it certainly does not take into consideration the use of calcium oxide as a root canal medication in the treatment of infected root canals. Much of the current confusion in the minds of the public about the efficacy of root canal therapy has been precipitated by the book “Root Canal Cover Ups” written by George Meinig, D.D.S., past president of the American Association of Endodontists. Dr. Meinig extensively cites the work of Dr. Price and concludes that there is a serious problem with root canal therapy and teeth that have had root canal treatment. This of course, is a major break with his own previous training and the policies of both the American Association of Endodontists. and the American Dental Association. Patients going to an “establishment” endodontist or dentist who does not subscribe to the focal infection theory are given a much different picture on the efficacy of root canal treatment. Here again, establishment protocols for endodontic treatment rely heavily on the use of some very toxic chemicals and cements.

Key References

Ingle JI Bakland LK., Endodontics (Fourth Edition), 1994, Williams & Wilkins, Malvern, PA.
Debelian et al., (1994). Systemic diseases caused by oral microorganisms. Endod. Dent. Traumatol. 10:57-65.
Nagaoka et. al., (1995). Bacterial invasion into dentinal tubules of human vital and nonvital teeth. J. Endodon. 21:70-73.
Green et al., (1997). Radiographic and histological periapical findings of root canal treated teeth in cadaver. Oral Surg. Oral Med. Oral Pathol. Oral Radiol.Endod.83:707-711.
Seltzer, S. (1999). J. Endodon. 25:818-822.
Intraradicular Bacteria and Fungi in Root-filled, Asymptomatic Human Teeth with Therapy-resistant Periapical Lesions: A Long-term Light and Electron Microscopic Follow-up Study. Nair PN, Sjogren U, Krey G, Kahnberg KE, Sundqvist G. Journal o f Endodontics December, 1990, 16(12):580-588. Dept. of Oral Structural Biology and Dept. of Endodontics, Dental Institute, University of Zurich, Zurich, Switzerland.
Nair et al., (1990). Journal of Endodontics 16:580-588.
Ando N. and Hoshino E. (1990). Predominant obligate anaerobes invading the deep layers of root canal dentine. International Endodontics Journal 23:20-27.
Lin, Skribner & Gaengler. (1992). J. Endodon. 18:625-627.
Brisman, Brisman and Moses (2001). JADA 132:191-195.
Langeland, K. Letter to the Editor, ADA News, Jan 16, 1984, page 10.American Association of Endodontists, recertification documents. 1989.
Tronstad L, et al. Endo Dent Traumatol 3:86-90, 1987.
Tronstad L. et al. Periapical bacterial plaque in teeth refractory to endodontic treatment.
J Dent Res. Vol 69 (Spec Issue), pane 300, Abstract #1529, March 1990.
Meinig, G. Root Canal Cover Up. 1994. Bion Publishing, Ojai, CA
Georgopoulou M.. et al. In vitro evaluation of the effectiveness of calcium hydroxide and paramonochlorophenol on anaerobic bacteria from the root canal. Endo Dent Traumatol 9(6):249?253, Dec 1993
Cavalleri et al. Comparison of calcium hydroxide and calcium oxide for intercanal medication. G-Ital-Endodonzia 4(3):8?13, 1990.
Messing JJ., Stock CJR. Color Atlas of Endodontics, 1988: pp 178?180, Wolfe Medical Publications Ltd. C.V. Mosby Co., St. Louis.