Table of Contents
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!
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.
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 above 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 on page 2). 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 (i.e.. 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.
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.