First of all, to understand how a root canal works, we need to have a basic understanding of the anatomy of the tooth. A tooth is hollow, like our bones, has several layers. The outermost layer (above the gum-line) is the enamel. Enamel is the hardest and most mineralized substance in the body. Beneath the gum-line, a substance we call cementum covers the tooth roots. Under the enamel and cementum is the dentin. The dentin is about as hard as bone, and, unlike the enamel, dentin contains nerve endings. Beneath the dentin is the dental pulp.
The pulp is a vascular tissue, including capillaries, larger blood vessels, connective tissue, nerve fibers, and cells including odontoblasts, fibroblasts, macrophages, and lymphocytes. The pulp needs to nourish the tooth during its growth and development. After a tooth is fully mature, the only function of the pulp is to let us know if there is damage or infection by transmitting pain.
How does the pulp become infected?
The most common way for the pulp to become infected is from an untreated cavity. A cavity is formed by acid in a rather unexpected way. Inside everyone’s mouth is a legion of bacteria – they are completely normal and there is nothing you can do about them. Some of these bacteria metabolize (eat) carbohydrate-containing foods or beverages and make acid as a by-product. The acid is strong enough to eat through the enamel and dentin. If left untreated, it will eventually expose the underlying pulp to bacteria inside our mouths and it gets infected.
The pulp can also get infection from trauma to the tooth. A blow to a tooth can cut off the blood supply to the tooth from our jawbone, and cause the pulp tissue to slowly die. Interestingly, a tooth that breaks within the enamel and dentin during trauma is less likely needing a root canal in the future because the fracture may absorb the trauma, sparing blood flow to the tooth.
A third way a tooth can get an infection is if there is long standing periodontal (gum) disease around the tooth. Bacteria from the infected gums can enter the tooth through small opening on the root surface (accessory canals) and cause a retrograde infection. Whatever way the tooth becomes infected, the pulp eventually dies, and over time, will cause a painful dental abscess within the surrounding jawbone.
How will I know if I have a tooth infection?
A tooth that becomes sensitive to hot or cold food or beverages or hurts when biting down may indicate an tooth with infection. A tooth that has discoloring or that causes the gums to swell around a tooth may also indicate a dental infection. In some cases, a tooth will have no symptoms, but a dental exam and x-ray will reveal a tooth that requires root canal.
If the tooth gets an infection, why can’t I use an antibiotic to treat it?
If a tooth has an infection of the pulp, the only options are root canal treatment or extraction. As the pulp dies, the hollow tooth becomes a reservoir for bacteria to hide from the body’s immune system and any drugs that could fight the infection. In some cases a dentist will prescribe antibiotics during or after root canal treatment to kill bacteria within the jawbone and tissues surrounding the tooth, but recent research has shown that this is usually unnecessary.
What’s it like getting a root canal, and does it hurt?
Root canal treatment is a complex procedure that requires both skill and experience. The dentist numbs the area of the tooth infection with local anesthesia (usually xylocaine or bupivacaine, not novocain which many dentists were using decades ago). A dentist places a clamp over the tooth, and a rubber membrane (rubber dam) is spread over the clamp to isolate the tooth and prepare it for the operation.
A small hole is made through the enamel and dentin, and into the pulp. The pulp is then removed with small stainless steel files of increasing diameter. After we remove the pulp, we shape the inside walls of the roots, almost like a sculpture. Nickel/Titanium files that fit on a slow speed drill can aid in shaping the canals. During the procedure, fluids (irrigants) such as sodium hypochloride (bleach) and we use a compound containing ethylenediamine-tetraacetate (EDTA) to both kill remaining pulp tissue and bacteria within the roots, and remove dentin shavings which the files produce.
After we remove the pulp and shape the inside of the roots, we dry the canal with paper cones. We fill the canal(s) with Gutta-percha. In 1867, Bowman introduces a miraculous substance called gutta-percha. It is a pure form of Mazer Wood Trees indigenous to Indonesia and Malaysia that combines with zinc oxide and other materials to form the rubbery filling that we place into the tooth roots. We then cement the Gutta-percha into the roots with a sealer that usually contains zinc oxide and eugenol. The goal of the filling procedure is to hermetically seal off the tooth against bacteria.
How do you fill the root canal?
There are two main techniques to filling a root canal, lateral condensation and warm vertical condensation. Although research is scanty, warm vertical condensation appears to have the advantage of more completely filling the tooth roots, especially the accessory canals.
Root canal treatment is usually not painful. With the effective use of anesthesia and modern techniques, most dentist can complete a root canal treatment in one visit, and within one hour. A tooth will be sensitive for a few days after root canal treatment, and your dentist can prescribe you medication to alleviate the pain. In the meantime, do not eat on the side of the mouth that has the root canal for a few days.
Do different teeth have different numbers of root canals?
Teeth in the front of the mouth (incisors and canines ) usually have one root, and one nerve canal within the root. Teeth on the side of the mouth (premolars) usually have one or two roots and one or two root canals. The upper back teeth (molars) usually have three roots, and three or four root canals. Lower back teeth (molars) usually have two roots and three or four root canals. Generally speaking, the more nerve canals the tooth has, the more difficult the root canal is to complete.
Can any dentist do a root canal?
All dentists train to do root canals in dental school. However, skill levels and experience vary widely from dentist to dentist. An general dentist with experience can do almost all root canal treatment successfully, but some general dentists prefer to have a root canal specialist (an endodontist) perform root canal on their patients.
How successful are root canals?
Root canals are successful about 90 percent of the time when the dentist correct performs the procedure. Teeth that have had root canal can become brittle and are susceptible to fracture. In most cases, it is advisable to place acrown (cap) over a tooth that has had root canal to rebuild and protect it.
Why do some root canals fail, and how will I know?
If a dentist leaves some of the pulp inside the root, a tooth with a root canal can fail. The gutta-percha does not completely seal off the tooth from bacteria, the tooth is damaged during the procedure (perforation), or the tooth fractures between the roots. In most cases, a tooth with a failing root canal will cause pain, usually when biting down.
What can I do if the root canal fails?
In some cases, we can retreat the root canal. We then remove the old gutta-percha filling, reshape and clean the tooth, and then refill. If this is not possible, we can perform an apicoectomy procedure. In an apicoectomy, we surgically remove the tip of the root, and place a filling over the cut root tip. If these measures fail, the tooth may need extracting.
Schedule A Root Canals Appointment
In conclusion, give us a call at (480) 551-9900 if you have any root canal questions or would like to schedule a root canals consultation with an endodontist.