Root canal
Root canals are the long passages full of soft tissue deep within the
dentin of a tooth, adjoining the pulp chamber. In
dentistry, a pulpectomy is an
endodontic treatment to cure an infection of the root canal; informally a
root canal. A root canal, coupled with internal tooth bleaching, is also used to fix teeth that have blackened because of infiltration of decayed soft tissue into the
dentin in the teeth, most often seen in frontal incisors that have been injured through a sudden impact.
Encyclopedia
Root canals are the long passages full of soft tissue deep within the
dentin of a tooth, adjoining the pulp chamber. In
dentistry, a
pulpectomy is an
endodontic treatment to cure an infection of the root canal; informally a
root canal. A root canal, coupled with internal tooth bleaching, is also used to fix teeth that have blackened because of infiltration of decayed soft tissue into the
dentin in the teeth, most often seen in frontal incisors that have been injured through a sudden impact.
Tooth structure
At the center of a
tooth is a hollow area that houses soft tissue, known as pulp. This hollow area contains a relatively wide space towards the chewing surface of the tooth called the pulp chamber. This pulp chamber is connected to the tip of the root of the tooth via thin hollow pipe-like canals—hence, the term "root canal". Human teeth normally have one to four canals; teeth toward the back have the most canals. These canals run through the centre of the roots like pencil lead runs through the length of a pencil. The tooth receives nutrition through the blood vessels and nerves traversing these canals. Occasionally, a cavity on the outside of the tooth may allow this soft tissue to become infected. If left untreated a serious jaw infection can result. The infection and inflammation is very painful in most cases. Treatment should take place before this happens.
Advice for Patients undergoing Root Canal Treatment
Root treatments, as they are widely known, are much-feared by many people - and sometimes with good reason. The sensitive nature of teeth that require work of this sort lends itself to them being more sensitive to the work, akin to
bruising of the skin. Patients undergoing root canals should heed a few simple, but effective, steps to reduce pain associated with such procedures. The first step would be to consider, at the discretion of one's dentist, a course of antibiotics although these are only appropriate in the case of infected teeth. Failing that, or as an accompaniment, patients may wish to follow a couple of days' course of NSAIDs which will reduce inflamation in the nerve and reduce sensitivity. In extreme cases patients should brush the teeth and gums more regularly, taking care not to miss any areas that are sensitive due to infection - this will reduce the swelling over time and relieve some of the pressure under the tooth until it can be seen to. Root treatments can be as pain-free as regular fillings if the area is properly tended to, and in certain cases the nerve is already dead so the entire treatment can be completed painlessly without an analgesic administered. In almost all cases the pain associated historically with this procedure can be avoided easily.
Root canal treatment
Sometimes a tooth is considered so threatened that future infection is considered likely or inevitable, and a pulpectomy is advisable to prevent it. But usually some inflammation and/or infection is already present, within or below the tooth. To cure the infection and save the
tooth, it is necessary for the dentist to drill into the pulp chamber, and remove the infected pulp by scraping it out of the root canals. Once that is done, the dentist fills the cavity with an inert material and seals up the opening. This procedure is known as
root canal therapy. If enough of the tooth has been damaged, or removed as a result of the treatment, a crown may be required.
The standard filling material is
Gutta-percha, a
thermoplastic polymer of
isoprene, which is melted and injected to fill the root canal passages. Barium is added to the isoprene so the material will be opaque to
X-rays, allowing verification afterwards that the passages have been properly completely filled in, without voids.
For patients, root canal therapy is one of the most feared procedures in all of dentistry; dental professionals assert that modern root canal treatment is relatively painless because the pain can be controlled. Lidocaine is a commonly used local anesthetic. Pain control medication may be used either before or after treatment. However, in some cases it may be very difficult to achieve pain control before performing a root canal. For example, if a patient has an abscessed tooth, with a swollen area or "fluid-filled gum blister" next to the tooth, the pus in the abscess may contain acids that inactivate any anesthetic injected around the tooth. In this case, it is best for the dentist to drain the abscess by cutting it to let the pus drain out. Releasing the pus releases pressure built up around the tooth; this pressure causes much pain. The dentist then prescribes a week of antibiotics such as penicillin, which will reduce the infection and pus, making it easier to anesthetize the tooth when the patient returns one week later. The dentist could also open up the tooth and let the pus drain through the tooth, and could leave the tooth open for a few days to help relieve pressure. At this first visit, the dentist must ensure that the patient is not biting into the tooth, which could also trigger pain. Sometimes the dentist performs preliminary treatment of the tooth by removing all of the infected pulp of the tooth and applying a dressing and temporary filling to the tooth. This is called a "pulpectomy". The dentist may also remove just the coronal portion of the dental pulp, which contains 90% of the nerve tissue, and leave intact the pulp in the canals. This procedure, called a "pulpotomy", tends to essentially eliminate all the pain. A "pulpotomy" may be a relatively definitive treatment for infected primary teeth. The pulpectomy and pulpotomy procedures eliminate most all pain until the follow-up visit for finishing the root canal. But if the pain returns, it means any of three things: the patient is biting into the tooth, there is still a significant amount of sensitive nerve material left in the tooth, or there is still more pus building up inside and around the infected tooth. All of these cause pain.
After removing as much of the internal pulp as possible, the root canals can be temporarily filled with
calcium hydroxide paste. This strong alkaline base is left in for a week or more to disinfect and reduce inflammation in surrounding tissue.
Ibuprofen taken orally is commonly used before and/or after these procedures to reduce inflammation.
After receiving a root canal, the tooth should be protected with a crown that covers the cusps of the tooth. Otherwise, over the years the tooth will almost certainly fracture, since root canals remove tooth structure from the tooth and undermine the tooth's structural integrity. Also, root canal teeth tend to be more brittle than teeth not treated with a root canal. Placement of a crown or cusp-protecting cast gold covering is recommended also because these have the best ability to seal the root canaled tooth. If the tooth is not perfectly sealed, the root canal may leak, causing eventual failure of the root canal.
The procedure is often complicated, depending on circumstances, and may involve multiple visits over a period of weeks. The cost is high, by local standards. In the US, it would typically cost US$1,000—though exceeded by the even more expensive related crown procedure, typically around US$2,000. In India, the root canal procedure would typically cost INR 1,500, when performed by an endodontist — and the crown procedure, for a ceramic crown, would cost around INR 2,000.
Innovation
In the last ten to twenty years, there have been great innovations in the art and science of root canal therapy. Dentists now must be educated on the current concepts in order to optimally perform a root canal. Root canals have become more automated and can be performed faster, thanks to advances in automated mechanical instrumentation of teeth and more advanced root canal filling methods. Dentists also possess newer technologies that allow more efficient, scientific measurements to be taken of the dimensions of the root canal that must be filled. Many dentists use microscopes to perform root canals, and the general consensus is that root canals performed using microscopes or other forms of magnification are more likely to succeed than those performed without them. Although general dentists are becoming versed in these advanced technologies, they are still more likely to be used by specialist root canal doctors . An Italian dentist named Arnaldo Castellucci has recently authored a three volume treatise on endodontics which thoroughly covers these modern concepts.
Laser root canal procedures are a controversial innovation. Lasers may be fast but not thoroughly disinfect the whole tooth, and may cause damage.
Failure
Sometimes root canals fail. Patients should be educated on some of the reasons why root canals may fail. They may fail if the dentist does not find, clean and fill all of the root canals within a tooth. For example, on a top molar tooth, there is a more than 90% chance that the tooth has four canals instead of just three. But the fourth canal, often called a "mesio-buccal", tends to be very difficult to see and often requires special instruments and magnification in order to see it. So, it may be missed, and this infected canal may cause a continued infection or "flare up" of the tooth. Any tooth may have more than one canal, which may be missed while performing the root canal. Sometimes the canal may be unusually shaped, making it impossible to fill it completely, so that some infected material is still left in the canal. Sometimes the canal filling does not extend deeply enough into the canal, or it does not fill the canal as much as it should. Sometimes a tooth root may be perforated while the root canal is being performed, making it difficult to fill the tooth. The hole may be filled with a material derived from natural cement called "MTA", although usually a specialist would perform this procedure. Fortunately, a specialist can often re-treat and definitively heal up these teeth, often years after the initial root canal procedure.
Alternatives
Claims have been made that it is impossible to fully sterilize a tooth internally, or fill it in a perfectly inert biocompatible permanent fashion. There is an ongoing risk of infection, which may pose dangers to the rest of the body. Unfortunately, there is generally no satisfactory alternative. Pulling the tooth leaves a gap which poses both aesthetic and functional problems, and endangers the structure of the adjacent teeth. The pain associated with a failed root canal can be very intense.
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