  Tooth
Anatomy
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, and is composed of several layers. The outermost layer (above the gum-line)
is called the enamel. Enamel is the hardest and most mineralized substance in the body. Beneath the
gum-line, a substance called 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, composed of capillaries, larger
blood vessels, connective tissue, nerve fibers, and cells including odontoblasts, fibroblasts, macrophages,
and lymphocytes. The pulp is needed 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 it is damaged or infected by transmitting
pain.
Sometimes the pulp becomes infected. When this happens, it must be removed with root canal
therapy. A root canal is the only way to save the tooth. A mature tooth can survive very well without the
pulp.
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 infected 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 to need root canal in the future because
the fracture may absorb the trauma, sparing blood flow to the tooth.
A third way a tooth can become infected 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 an infected tooth?
A tooth that becomes sensitive to hot or cold food or beverages or hurts when
biting down may indicate an infected tooth. A tooth that becomes discolored 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 is infected, 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 therapy 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 therapy
to kill bacteria within the jawbone and tissues surrounding the tooth, but recent research has shown
that this is usually unnecessary.
Do different teeth have different numbers of root canals?
Teeth in the front of the mouth called incisors and canines usually have one root, and one nerve canal
within the root. Teeth on the side of the mouth called 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 complicated the root canal is tocomplete.
Can any dentist do a root canal?
All dentists are trained to do root canals in dental school. However, skill levels and experience vary widely from dentist to
dentist. An experienced general dentist can do almost all root canal therapy 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 they are done properly. Teeth that have had root canal can become
brittle and are susceptible to fracture. In most cases, it is advisable to have a crown (cap) placed over a
tooth that has had root canal to rebuild and protect it.
Why do some root canals fail, and how will I know?
A tooth that has root canal can fail if some of the pulp is left inside the roots (a canal is missed), 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, the root canal can be re-treated. The old gutta-percha filling is removed, the tooth is reshaped and cleaned,
and then re-filled. If this is not possible, a procedure called an apicoectomy can be preformed. In an
apicoectomy, the tip of the root is surgically removed, and a filling is placed over the cut root tip. If these
measures fail, the tooth may have to be extracted.
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Root canal therapy is one of the most dreaded (by the patient) facets of dentistry. However,
reality is that the rotary root canal handpiece is the newest most effective and efficient way of
performing root canals. Using this highly innovative technology, Dr. Shikha Batra can perform
one visit painless root canals in less than one hour. This machine allows her to perform root
canals from beginning to end... cutting back on traditional root canal therapies, which often
takes multiple visits to the dentist. Dr. Batra uses an electically driven motor to actually clean the
infection in the tooth. This instrument also shapes the tooth to adequately hold the filling
material. So the next time you need a root canal, be sure to inquire about the newest and latest
technology of rotary root canal therapy!