Root Canals

Left alone, abscesses can become quite serious. In the days before antibiotics and modern surgery, dental abscess was a common cause of death. Upon occasion, especially in the case of an untreated abscess of an upper front tooth, the patient can get a brain abscess which can kill him. This brain infection is called cavernous sinus thrombosis. Click the image to the left to see my page explaining the mechanics of cavernous sinus thrombosis and its relationship to the "dangerous triangle".

Another killer is Ludwig's angina (See image to the right). This infection is caused by an abscess of a lower tooth. The major symptom is severe swelling under the tongue, chin and neck. The swelling may become so severe that the patient can no longer breathe. Before the advent of modern dentistry, this infection was one of the most frequent causes of death, particularly among the wealthy upper classes who had access to large amounts of sugar.

For a large part of human history, the only treatment for these death dealing infections was extraction of the offending tooth. Usually done with an instrument known as a pelican, and without anesthesia except for a glass or two of whiskey (if the patient could afford it), the tooth was RIPPED out as quickly as possible, most frequently breaking the tooth. Even if the tooth broke leaving the roots still in place, the procedure could save the patient's life by affecting drainage of the pus and relief of the pressure of the abscess.

Even today, extraction of the offending tooth is still a viable alternative for relief of a toothache. It is usually less expensive to remove a tooth than it is to do the root canal, however, many of the most damaged teeth must be extracted surgically which increases the cost of even this relatively less expensive alternative.

But today, you can also opt to keep your teeth, even if they are painful or abscessed. You would do this to avoid the trauma of an extraction, and to retain your natural tooth. They don't grow back once pulled out! Properly treated, an endodonticly treated tooth remains a useful tooth with no continuing pain or abscess.

How A Root Canal procedure is done

When we begin the root canal procedure, we anesthetize the patient with one or more shots of local anesthesia to produce profound numbness. Then, if there is enough left of the crown of the tooth above gum line, (this is not always the case) we put a tiny clamp around the tooth and slip a rubber sheet with a hole in it around the clamp. This is called a rubber dam, and it isolates the tooth from the rest of the mouth. We do this in order to prevent dropping any of the tiny instruments we use to clean out the tooth into the patient's mouth, and to retract the tongue , lips and cheek so we have a good clear field in which to work.

Now we are ready to begin gaining access to the dental pulp. First a hole is drilled in the top of the tooth above the position where the dentist expects to find the nerve. (In front teeth the hole is made on the tongue side of the tooth so it doesn't show from the front.) The diagram to the right shows the situation we face when we first enter the tooth. The access is denoted by the gray cylinder above the pulp. The nerve may be red and alive as denoted by the red color at the tip of the pulp, or it may already be dead and draining out of the root causing abscesses as denoted by the green balls at the root tips.

The nerve in the large pulp chamber at the top of the tooth is cleaned out using a round bur on a slow speed handpiece (drill). Then the canals are entered with a series of tiny files which look from a distance like flexible pins with serrations along their lengths. These are inserted into each canal, all the way to the tip starting with a very thin little file followed by progressively fatter files until the entire mass of the nerve is removed and the sides of the root canals are made smooth and clean. In between each pass with the files, the tooth is washed (irrigated) with a dilute solution of laundry bleach (Clorox) in order to wash out the debris, and to sterilize and chemically neutralize any dead tissue that may be missed by the files. (One of the reasons for the rubber dam is to keep the bleach out of the patient's mouth.) More recently, dentists have begun using a 2% solution of chlorhexidine instead of bleach as an irrigating solution. Chlorhexidine is a powerful disinfectant and is not as caustic or as objectionable if it happens to get under the rubber dam and into the patient's mouth.

Finally, once the tooth is entirely clean internally, it is dried out with tiny paper points, and each canal is fitted with the appropriate diameter rubber cone that will entirely fill and block that canal. Each file is numbered to denote its diameter, and there is a corresponding rubber cone size to be used in canals finished to that size file. The rubber is a special form called gutta percha. It is less refined than regular rubber and is somewhat gummy, sticking to the walls of the canal and thoroughly waterproofing them. It happens to be pink in color, and is the reason the third diagram above has a pink filling under the final filling in the access hole.

The diagram to the left shows a file in the access preparation of a premolar tooth. The file is worked up and down drawing the rasps against the sides of the canal. Over time with quite a lot of elbow work, the files strip tooth structure from the inside of the root canal making it smooth and debris free. The gutta percha is usually placed into the canal along with a white creamy cement which is supposed to flow into any area where the gutta percha and files cannot reach.

After the first (master) gutta percha point is inserted to the tip of the root, more (accessory) gutta percha points are inserted beside that one in order to place pressure on the cement and force the cement into every nook and cranny, and in order to force the gutta percha against the walls of the canal thus sealing it entirely. The X-ray at the right shows a finished root canal. The arrow denotes a "lateral canal" which ended up sealed even though the files never traversed it. It has filled with cement forced into it by the lateral pressure of the accessory gutta percha points placed beside the first master point.

If you look closely at the x-ray on the right, you can see that the master gutta percha point has been inserted slightly beyond the tip of the root into bone. This is a mistake, but it is of no consequence to the success of the root canal since the gutta percha and the cement are inert and do not cause inflammation at the tip of the root even when embedded in bone.

The real anatomy of the nerve inside a tooth

When we explain how a dentist does the procedure known as a root canal, we generally show a diagram of a tooth (like the one above) with a rather idealized root anatomy. This consists of a simple pulp chamber located inside the crown portion of the tooth, and one or more straight, uncomplicated root canals leading from the pulp chamber down each root of the tooth. A glance at the image at the left shows that the reality is more complicated. The root system in any given tooth is likely to be more like a network of nerves, blood vessels and connective tissue that snake around inside the tooth. While a root canal procedure consists of removing all of the dead nerve tissue from this network, in reality, it is obvious that it would be close to impossible to traverse the horizontal components with an endodontic file. Thus, any dentist doing endodontic procedures merely does the best he can. Just as long as the tip of the roots are properly sealed, the procedure will be a success since any dead tissue remaining will be sealed inside the tooth where it is isolated from the rest of the body. Of course, this does not always happen, and some root canal treatments fail in spite of the dentist's best intentions and technique simply because the odds were stacked against him from the beginning.

Do Root canals work?

The short answer is yes, root canals work about 95% of the time. The image to the right is typical of the radiographic (x-ray) appearance of an abscessed tooth. Note the dark "balloons" at the tips of the root of the broken-down molar. These "balloons are known as granulomas. They represent soft tissue that has formed around the tips of the root to deal with the dead material inside of the root canals. As the dead material and its byproducts drain into the bone, the cells in the local area have formed "granulation tissue" which is filled with tiny blood vessels (technically, the tissue is "highly vascularized"). These blood vessels provide a steady supply of white blood cells which "eat" (phagocitize) the toxic material and keep it from getting into the general circulation where it could cause more widespread infections. Most of the time this situation is "chronic" and essentially painless, but upon occasion, when the body's defenses are directed elsewhere, such as when the patient is under the influence of other physical or psychological challenges, this situation may turn "acute" and lead to swelling, drainage and pain. Given enough antibiotics, this acute situation may eventually return to a symptomless chronic problem, only to erupt into another acute episode several months later.

The image on the left shows the same tooth about two years after its original endodontic treatment and restoration with a simple filling. As you can see, the granulation tissue at the tip of the roots has almost completely healed. Note that the disappearance of granulomas does not happen in every case, however the fact that the toxic tissue inside of the root canals has been debrided (cleaned up) and the root canals sealed, means that the situation is not likely to become acute again. The only thing that this tooth needs to complete the procedure is the placement of a crown to protect the tooth from breaking.

Why do Root Canals have such a bad reputation?

The most important single point to be made is that the vast majority of root canal procedures proceed painlessly, both during and after each visit!

Pain during the root canal appointment

Now finally, let me address the issue of pain as it relates to Endodontic therapy. Pain is always an issue in dentistry, and fear of pain is one of the major reasons why patients fail to seek help from a dentist until their emergency is so severe that they are literally driven to seek professional help! They may be terrified when they sit in that big chair, but as soon as the dentist makes them numb, they are so relieved, that they sometimes fall asleep. They discover almost immediately that--surprise--the shots are not very painful. In general, you hurt yourself more eight or ten times every day doing normal activity than the dentist hurts you with the shot. It's just that there is a tendency for patients to concentrate on the stimulus of the shot, and by doing that they magnify that stimulus into something much more unpleasant than it should be!

Generally, the anesthesia works very well with just one standard shot. This is especially true if you are not already in pain when you come to the office. On the other hand, inflamed tissue (hot, red, swollen and painful) is acidic in nature. The anesthesia is very PH sensitive. Anesthesia in a normal acid/base environment likes to seep into nerve fibers slowly, which is why anesthetics take some time to set under normal conditions. In an acid environment, fewer anesthetic molecules convert to a diffusible form. In order to overcome this difficulty, we use a LOT more anesthesia than we do if you are not already in pain when you present for treatment. (To learn more about the technical aspects of local anesthetics, please see my course on this subject.)

This is especially true when doing a root canal on a tooth. A vast majority of endodontic procedures go very smoothly with minimal anesthesia. If there is good evidence that the nerve is already dead, the patient may need NO anesthesia at all. (We do entire root canal treatments without any shots all the time!) A single shot is generally sufficient to totally anesthetize a tooth in order to complete a root canal procedure if that tooth does not already contain a badly inflamed live nerve.

On the other hand, some people present with what we call a hot tooth. A hot tooth is one in which the nerve is alive, but badly inflamed. The tooth is generally already very painful, especially to hot or cold stimuli. These are the ones that require multiple shots to get anesthetize. A vast majority of these will numb out with a few carpules of anesthesia administered in the normal way. A few, however, are so inflamed and acidic that the anesthesia cannot diffuse into the nerve fibers well enough to totally destroy the sensations generated by the nerve in the tooth. In these cases, we may resort to intrapulpal anesthesia. In this procedure, we will drill very quickly directly though the top of the tooth into the nerve chamber (a few seconds is generally sufficient time) and deliver a quick squirt of anesthesia directly into the nerve inside the tooth. It's fast, and always effective.

Pain after a root canal appointment

The best way to predict whether a root canal procedure will be painful after the procedure is to assess whether it was seriously painful before the procedure. The more painful the tooth before seeing the dentist, the more likely it is that it will be necessary to take pain medication after the root canal procedure is performed.

Click on the image to the right to see more on the anatomy and physiology of pain.

Pain after root canals, or between visits falls into four distinct categories and is treated differently depending upon which category it falls into.

Ghost pains happen after an amputation. In the case of someone who has recently had an arm amputated, he may experience pain in his fingers, even though the fingers are no longer there. These are caused by the brain's inability to acknowledge that the fingers are missing, and the pain results from the memory patterns still in place in the neural circuitry from the "stump", to the place in the brain where the pain was originally experienced. In the case of a root canal, the nerve inside the tooth is amputated. The patient may therefore experience ghost pain in the tooth for the same reason that the amputee experiences pain in his fingers. This type of pain may be sharp and shooting pain in the tooth, or a dull ache. These symptoms generally go away on their own and are either not treated, or are treated with a temporary course of Tylenol, Ibuprophen or another light analgesic.
Gas pressure buildup happens between visits after the nerve has been removed from the tooth, but before the canals and chamber are filled with gutta percha. The patient usually goes home after the first visit with an "empty" tooth. The canals and chamber are filed with dead air, and the access hole is closed with a temporary filling. Since air can expand or contract in an enclosed space (like inside the tooth) depending on the barometric pressure, (or the temperature,) the change in volume of the air can place pressure on the live tissues beyond the apex (root tip) in the bone. This is the reason that a tooth in this condition can cause pain when the patient flies in an airplane (low cabin pressure), or on a rainy day (low barometric pressure), or when he drinks hot or cold fluids (air expands and contracts depending on the temperature). This type of pain is generally ignored, or treated with mild analgesics since the pressure generally subsides by itself in a day or so. Upon occasion, the pain persists and the tooth becomes painful to touch for more than a day. In this case, simply removing the temporary filling from the access hole in the top of the tooth will relieve the pain immediately. NO Shot! Just relief!. If the tooth is dry inside, the filling can be replaced after the pressure is relieved.
A Periapical abscess is an actual buildup of fluid in the bone at the tip of the root. This fluid may be sterile (germ free) or it may be the result of an infection due to germs that were introduced beyond the tip of the root during the endodontic procedure. This is a common problem during endodontic therapy. Infection is generally due to the fact that the tooth was infected before the treatment was started. Sometimes, a "sterile abscess" happens because a small amount of the irrigation fluid that is used to clean and sterilize the canals may be expressed beyond the tip of the root during the filing and irrigation procedure explained above. Both types of abscesses manifest as pain to pressure on the tooth. Sometimes painful swelling of the jaw around the tooth may also be present. Generally, the pain is easily relieved by removing the temporary filling in the access hole at the top of the tooth to allow for the fluid to drain. Some dentists may allow the hole to remain open for several days during which the patient is treated with penicillin or another antibiotic. After the swelling and drainage are gone the canals and chamber are cleaned and disinfected and a new temporary filling is placed over the access. Sometimes this procedure must be repeated several times before the root canal can be finished. Other dentists will allow drainage for only 30 or 40 minutes before again drying and closing the tooth.
Hyperocclusion is another term for grinding and clenching your teeth. It is the prime cause of TMJ disorders and is responsible for a great deal of dental misery including generalized hypersensitivity of the teeth to cold. One of the first things a dentist does when performing endodontic treatment on any tooth is to "reduce the occlusion" on the tooth, which means to grind the tooth down so that it does not make contact with the opposing teeth. If he fails to do this, the prognosis for the root canal is very poor indeed.

The periodontal ligament that surrounds the tooth widens at the tip of the root. The ligament in this area is called the "hammock ligament". The blood vessels and nerve tissue that supply the dental pulp inside the tooth must traverse the hammock ligament in order to enter the tooth. Amputation of the nerve inside the tooth, (which is the technical definition of a root canal procedure) frequently causes some inflammation and swelling of the hammock ligament fibers. The Hammock ligament may be further inflamed by overextension of the file beyond the tip of the root during the procedure, as well as by the forcing of debris and fluids beyond the tip of the root into the hammock ligament during the cleaning of the canals. This, in turn can cause a slight elongation of the tooth in its socket which means that unless the top of the tooth is shortened (ie. the occlusion is adjusted) to avoid hitting the opposing teeth, normal biting, and especially grinding and clenching (hyperocclusion) can traumatize the hammock ligament. This causes further swelling and pain in the ligament which increases the elongation of the tooth and further trauma from hyperocclusion which causes further swelling etc. etc. This vicious cycle is very painful. Even very slight pressure on the tooth can can bring tears to the eyes of a Marine! The treatment for this problem is generally to reduce the occlusion on the tooth so that it cannot make contact with the opposing dentition.

Strangely enough, severe bruxing habits (unconscious grinding and clenching--see my page on TMJ) can cause misery in a tooth under endodontic treatment even if the occlusion has been properly adjusted, and the offending tooth makes absolutely no contact with the opposing dentition! The reason for this is not entirely clear, but it may be associated with changes in blood flow in the bone surrounding the tooth, due to the extreme pressure placed on the bone by hyperocclusion on the adjacent teeth. In general, people who seem to suffer terrible and prolonged pain during the course of endodontic therapy frequently fall into this category. If you are one of those people, it is often helpful to begin treatment for your TMJ condition during the course of endodontic therapy. In my office, this generally means construction of an emergency TMJ deprogramming device which will usually relieve severe, prolonged pain within a few hours.

Failed root canal procedures

The final reason that root canals have such a poor reputation is that they do not always work. Sometimes, in spite the best intentions and the best technical skill, the tooth never really ceases to be painful or bothersome in some way. This happens in the vicinity of about 5% of the time. When this happens, either the patient lives with the results, or the tooth is finally extracted and replaced with a bridge, partial denture or an implant. There are many reasons that this might happen. Below is a partial list of problems that may have occurred to cause the failure:

One or more extra canals may be lurking in the depths of the tooth that the dentist was unable to instrument. Dead, or partially alive tissue hidden inside the tooth can cause abscesses or ongoing bouts of pain and may lead to failure. The real anatomy of the nerve is a tricky matter, and sometimes it is literally impossible to remove or inactivate it all.
A fractured root may cause failure of a root canal. Teeth with dead nerves are always brittle. This is as true for parts of the tooth that are buried under the gums as for parts of the tooth that can be seen in the mouth. A fractured root generally is impossible to repair and this means the loss of the tooth. For a better understanding of cracked teeth see my page on this subject.
Hypersensitivity to the materials used to fill the canals may cause the patient's physiology to "reject" the tooth. This is a very rare occurrence since the gutta percha used to fill the canal is quite inert and is generally very well tolerated by human physiology. The cement used to bind the gutta percha to the inside of the canal and to seal the apex has been formulated to have benign characteristics as well, but in both cases, patients have been known to develop allergies to these materials.
Sargenti Root canal procedures were a fad that swept through dentistry between the late 1950's and the early 1970's, although a relatively small number of practitioners still use this technique today. The technique begins as a standard root canal procedure, but deviates from standard in that it relies less on thorough instrumentation (cleaning of the inside of the canals) and more on the use of a caustic root filling paste which is supposed to embalm the remaining nerve thus inactivating it. The Sargenti technique uses this paste to seal the canals instead of the gutta percha root filling used in the standard technique.

When dentists first started to use Sargentii, it seemed to work quite well. It was fast, (generally only one visit) and enabled general dentists to provide endodontic services at reduced cost to the patient. Even if some live or dead nerve was left behind inside the canals, the paste seemed to deactivate it as advertised provided that none of the Sargenti paste was extruded beyond the tip of the root of the tooth. In some cases, however, problems became evident years later when it was found that the paste (which actually contains paraformaldehyde -- embalming fluid) could escape from the tooth into the bone, especially if the patient bruxes (grinds his teeth). Thus patients began to have belated pain, numbness and abscesses in teeth that had been treated years before.

This situation cannot be reversed and the teeth must be extracted. In rare cases, even extraction of the tooth is not enough to relieve the problems created by the presence of the paraformaldehyde in the bone, and extensive surgery may be required. If you have had a Sargenti root canal, don't panic. MOST work out with no problems. No dental school today teaches their students to use the Sargenti technique, and most dental malpractice insurers will not cover damage caused by dentists who use root canal sealers which contain paraformaldehyde. For more on this technique, click here or here.

The Apicoectomy and retrofil. The last frontier!

In general, whenever a root canal procedure seems to have failed, the dentist's first reaction is to try to redo the root canal in standard fashion. In other words, he or she will try to remove the old root filling materials (usually gutta percha and endodontic cement) and re-instrument the tooth before replacing them. This is not always possible to do since it can be quite difficult to remove the original root filling. It is often impossible to do if a post has been placed in the canal to stabilize the subsequent filling for placement of a crown. In cases like this, if the failure can be demonstrated (generally using x-rays) to be associated with one root, it is possible to do a surgical procedure to remove the offending root tip along with any abscess associated with it. This is called an Apicoectomy procedure.

An apicoectomy is done by cutting a soft tissue flap just above the tip of the root canal treated tooth, puncturing through the bone and amputating the root tip. This generally removes any offending dead (or living) tissue and often cures the problem. In some instances, the dentist will prepare a tiny cavity preparation at the tip of the root and seal off the rest of the canal with a tiny amalgam filling. If this is not possible, it is still often possible to melt some gutta percha at the tip of the root to seal it off. This is called a retrofill (retro="from behind"). Apicoectomies and retrofills are generally thought of as a last resort in an ongoing effort to save an otherwise hopeless endodontically treated tooth. They are especially useful in treating a failed root canal in a tooth with a post and core.

Internal/External Resorption

The three images above show a fairly rare, but interesting phenomenon called internal resorption. (Click on any of the images to see them enlarged.) The x-ray image to the left shows a tooth with a large filling that is close to the nerve. The yellow arrow points to the area of concern. Upon occasion, when a live nerve becomes irritated (in this case due to the close proximity of the filling), it may become "sick" and forget its usual function of remaining inert and keeping the tooth hydrated. When this happens, it may start to eat away at the very tooth that it is supposed to be protecting. The image in the center was taken a little over a year after the first x-ray, and shows a dark (radiolucent) area in the distal (back) root next to the furcation (where the two roots join together). This radiolucency represents a hole in the tooth structure at that point. The nerve simply ate away the tooth from the inside out. This hole is an example of internal resorption. The image on the right shows the extracted tooth in which the defect caused by the resorption is clearly visible.

The reason that this defect is labeled internal/external resorption is that a second phenomenon can cause the same defect. This involves cells in the periodontal ligament which forget their usual function of supporting the root of the tooth. If this happens, these external cells may eat the same hole in the tooth, this time from the outside in. Once the nerve is exposed, as it was in this image, it is impossible to tell from which direction the resorption started.

If the internal resorption is noted before it perforates through to the outside of the boundaries of the tooth, a root canal procedure will stop the process and save the tooth.

All back teeth with root canals should be protected with a crown.

WARNING: Once the pulp of the tooth has died or has been removed, the tooth no longer has its hydrating mechanism and becomes somewhat brittle and more prone to fracture. It is important that all back teeth (molars and premolars) that have been endodonticly treated be protected with crowns to prevent fracture and to restore their appearance. (This is somewhat less necessary with front teeth because they have a smaller biting table and, as a result, are less prone to fracture in function.)

Crowns are a procedure done in addition to the root canal and increases the ultimate expense of keeping the tooth. However it is well worth doing since it protects the investment of the root canal and is a good part of an overall treatment plan. These teeth have root canals, and have been prepared to receive crowns.

These are the crowns as they are received from the lab where they are fabricated. They are sitting on the plaster model of the crown preparations you see above.

Crowns are generally made of porcelain and not only look like teeth, but tend not to stain and can be built to correct the bad appearance of crooked, discolored and malformed teeth. Front teeth are frequently crowned even without root canals just to correct the patient's smile. This is what the prepared teeth look like immediately after crowns are inserted.

Can teeth with root canals, fillings, crowns or gum disease cause other systemic diseases such as fibromyalgia, scleroderma, multiple sclerosis, lupus, Chronic fatigue or various autoimmune diseases?

NO!! Teeth are not, in general, connected with any systemic diseases with one exception. Read this whole article for the complete scoop.

In 1900, the British physician William Hunter wrote an article in the British Medical Journal entitled "Oral Sepsis as a Cause of Disease". The article accused "conservative dentistry" (the preservation of the dentition by dental treatment) as the cause of a huge number of systemic diseases including arthritis, neuritis, myalgia, nephritis, osteomyelitis, endocarditis, brain abscess, skin abscess, pneumonia, asthma, anemia, indigestion, gastritis, pancreatitis, colitis, diabetes, emphysema, goiter, thyroiditis, Hodgkin’s disease, obscure fever (fever of unknown origin), and nervous diseases of all kinds. Hunter believed that the repair of teeth with gold crowns created "A perfect gold trap of sepsis of which the patient is the proud owner and no persuasion will induce him to part with it, for it cost him much money and it covers his black and decayed teeth." Hunter was not propounding anything especially new. The theory that "bad teeth" were the underlying cause of numerous systemic diseases had been well established long before Hunter wrote his famous paper.

The history of blaming teeth for human disease has a very long history going back to Hippocrates who is said to have reported the cure of arthritis after the removal of a tooth. Today, such diseases as chronic fatigue syndrome, fibromyalgia, lupus, multiple sclerosis, and Alzheimer's disease are mistakenly blamed on "bad" teeth.

Hunter's theories were later codified by Weston A. Price, D.D.S. (1870-1948). Price studied primitive cultures and concluded that "modern civilization" was the cause of ill health and that people living in primitive conditions were actually healthier than modern people. His examination of the primitive cultures in question were quite superficial, and his conclusions were simplistic ignoring such statistics as their short life expectancy, high rates of infant mortality, endemic diseases, and malnutrition. Price also performed poorly designed studies that led him to conclude that teeth treated with root canal therapy leaked bacteria or bacterial toxins into the body, causing all sorts of dreaded diseases including those attributed by Hunter to the theory of Oral Sepsis. Research studies performed in the 1930s and 1940s and those conducted in later years showed no relationship between the presence of endodontically treated teeth and the presence of illness. Instead, researchers found that people with root canal fillings were no more likely to be ill than people without them.

The technical name for the theory that encouraged souls in previous eras to blame systemic diseases on the presence of bad teeth is the "theory of anachoresis" (pronounced "ana-co-ree-sis"), or the "theory of focal infection". According to this theory, an infection in or around a tooth (the "focus of infection") could theoretically be carried by the bloodstream to other parts of the body. Originally, the hypothesis that a bad tooth could cause cancer or other systemic diseases was based on ancient holistic theories of medicine and "proven" by anecdotal evidence (the occasional case that seemed to confirm the theory). In the early 1800s, Benjamin Rush, an American physician and signer of the Declaration of Independence, is said to have observed the cure of a case of arthritis of the hip by tooth extraction.

The theory of focal infection probably reached its apotheosis in the 1920's, between the two world wars, when huge numbers of people were subjected to full mouth extraction of all their teeth, as well as removal of various "unnecessary" organs in order to cure every imaginable disease. One example of "research" in this area is on display in this excerpt from an essay on Victorian insane asylums in England, many of which were still in operation as late as the 1980's. Here, the emphasis was on curing madness:

"Attempts at cures were often more desperate than well-advised. One of the asylums of my city had the best-equipped operating theater of its time, where an enthusiastic psychiatrist partially eviscerated his patients and also removed all their teeth, on the theory that madness was caused by a chronic but undetected and subclinical infection (called “focal sepsis”) in the organs that he removed." (Click here to read this excellent--and long--essay by Theodore Dalrymple.)

Most of the applications of the theory of focal infection were disproved with the emerging science of the 1930's and 1940's. The reasons for the demise of the theory are as follows:

Science was never able to prove that the theory of focal infection was actually valid. Numerous instances of anecdotal evidence (the occasional case that seemed to confirm the theory) had been used for centuries to prove the theory of focal infection, but very few scientifically controlled experiments were carried out. In the limited number that were, the theory's advocates were never able to prove any linkage between teeth and systemic disease. As a result, they remained wedded to anecdotal proof. It is now generally accepted among the scientific community that anecdotal evidence is not a valid approach in scientific research.
When the offending tooth, teeth or organ was removed, patients rarely were cured of their disease, as promised by the proponents of the theory of focal infection. This eliminated much of the credibility of the theory.
Sometimes, the disease would actually be exacerbated (made worse) by the removal of the supposed focus of infection.
Improvement in dental care greatly reduced the incidence of widespread dental disease in the general population reducing the popularity of blaming bad teeth for systemic disease.
The advent of antibiotics largely eliminated much of the mortality associated with dental infections. This, along with improved overall dental health in the general population eliminated much of the anger that many people once directed toward their diseased teeth and reduced the previously widespread desire to have them all extracted and replaced with dentures.
The list of diseases that were supposedly caused by bad teeth kept shrinking as the true causes of these diseases were discovered over the course of time.
The unfavorable reaction to the "orgy" of dental extractions and tonsillectomies that were advocated by the proponents of the theory eventually undermined the trust of the population. From approximately the end of the nineteenth century up until shortly after WWII, millions of perfectly healthy people lost their perfectly healthy teeth due to the theory that early extraction would prevent numerous diseases later in life, and also because it was extremely lucrative for the surgeons who extracted the teeth, and the dentists who made the dentures.
Growing up in the 1950's, I once asked my grandmother, already quite old at the time, why she had false teeth. (The image to the right is of my grandparents in their nineties.) She told me that they were all extracted when she was 16 because of "pyorrhea". Pyorrhea is another term for gum disease, and knowing what I know today, I realize that sixteen year old kids don't lose their teeth to gum disease. My grandmother was another innocent victim of the ignorance of nineteenth and early twentieth century medical quackery!

The theory of focal infection is kept alive today by the American legal tort system (lawyers using junk science to turn a profit), the holistic health movement, and even by a relatively small number of dentists who rely on these debunked theories to sell holistic (spa) dentistry to wealthy patrons. Dentists selling these services generally are true believers. "The patient's ills can be cured if the offending teeth are extracted and replaced with implants, or if their amalgam fillings are all removed and replaced with composites or crowns." This belief is, however based on the debunked theories of Hunter and Price, and not on scientific evidence.

The holistic movement has tried to update the concept of anachoresis by renaming it. In the mid 1970's, the term "cavitational osteopathosis" ("CO") was coined. In the 1980's it was renamed "neuralgia inducing cavitational osteonecrosis" ("NICO"). The new names have not changed the concept underlying the theory; and the science underlying the theory remains the same as it was in the early 20th century.

This is not to say that there is NO validity to the theory of anachoresis. Bacteria from an infection any place in the body CAN be carried by the blood or lymphatic system to distant parts of the body where they can form another infection. The symptoms of this sort of anachoresis are, however, quite specific and do not resemble any disease entity except a straight forward organic infection. They include infections of the heart (sub-acute bacterial endocarditis), especially in persons who have had a history of rheumatic fever or heart murmur, and on rare occasions, infections of implanted appliances such as artificial joints. There is NO indication that there is a correlation between the teeth and any other disease entity for which the cause is otherwise unknown.

Can the mercury in amalgam fillings cause long term medical problems? Click here to find out