Endodontics is the branch of dentistry that deals with diseases of the tooth's pulp. The pulp is found in the center of the tooth and in canals (called root canals) inside the root of each tooth. Pulp includes connective tissue, nerves and blood vessels. Pulp nourishes the tooth when it first emerges through the gum. Once the tooth matures, the pulp can be removed without destroying the tooth. That's because each tooth also is nourished by a blood supply in the gums.
Removing the pulp is called endodontic treatment, but it is often referred to as root canal treatment or root canal therapy. Many people refer to pulp removal as "having a root canal." Root canal treatments are quite common. In the United States, they save about 24 million teeth each year.
Why Would You Need Root Canal Treatment?
Root canal treatment is needed for two main reasons. The first is infection. An untreated cavity is a common cause of pulp infection. The decay erodes the enamel and dentin of the tooth until it reaches a root canal. This allows bacteria to infect the pulp. Antibiotics can't get to infections inside teeth. The inflammation caused by the infection reduces the blood supply to the tooth. The reduced blood supply also keeps the pulp from healing.
The second reason for a root canal is damage to the pulp that can't be fixed. Trauma or a fractured tooth can damage the pulp. So can a lot of restoration, such as several fillings placed in the same tooth over a period of time. Sometimes, common dental procedures, such as preparing a tooth for a crown, can hurt the pulp. Then the tooth might need a root canal.
When the pulp is inflamed but not infected, it may heal on its own. Your dentist may want see if this will happen before doing root canal treatment. If the pulp remains inflamed, it can be painful and may lead to infection.
An infection in the pulp can affect the bone around the tooth. This can cause an abscess to form. The goal of root canal treatment is to save the tooth by removing the infected or damaged pulp, treating any infection, and filling the empty root canals with a material called gutta percha.
If root canal treatment is not done, an infected tooth may have to be extracted. It is better to keep your natural teeth if you can. If a tooth is missing, neighboring teeth can drift out of line. They also can be overstressed from chewing. Keeping your natural teeth also helps you to avoid other treatments, such as implants or bridges. Also, if you ignore an infected or injured tooth the infection can spread to other parts of your body.
Having root canal treatment on a tooth does not mean that the tooth will need to be pulled out in a few years. Once a tooth is treated, it almost always will last the rest of your life.
Signs and Symptoms
If you have an infection of the pulp, you may not feel any pain at first. But if it is not treated, the infection will cause pain and swelling. In some cases, an abscess will form.
Your tooth might need a root canal if:
- It hurts when you bite down on it, touch it or push on it
- It is sensitive to heat
- It is sensitive to cold for more than a couple of seconds
- There is swelling near the tooth
- It is discolored (whether it hurts or not)
- It is broken
To determine whether your tooth needs root canal treatment, your dentist will often place hot or cold substances against the tooth. The purpose is to see if it is more or less sensitive than a normal tooth. He or she will examine the tissues around the tooth and gently tap on the tooth to test for symptoms.
You also will be given X-rays of the bone around the tooth. The X-rays may show a widening of the ligament that holds the tooth in place or a dark spot at the tip of the root. If either of these is present, your dentist probably will recommend a root canal procedure.
Your dentist may need more information about the tooth. He or she may use an electric pulp tester. This hand-held device sends a small electric current through the tooth. It helps your dentist decide whether the pulp is alive. This test does not cause pain or a shock. You may feel a tingling sensation. It will stop when the tester is removed from the tooth.
An electric pulp tester should not be used if you have a cardiac pacemaker or any other electronic life-support device.
Length of Treatment
Root canal treatment can be done in one or more visits. It depends on the situation. An uncomplicated root canal treatment often can be completed in one visit. Some teeth may be more difficult to treat because of where they are in the mouth. Some teeth have more roots than other teeth. Treating a tooth with many roots takes longer. Some teeth have curved root canals that are difficult to find. If you have an infection, you will visit the dentist several times so that he or she can make sure that the infection is gone.
Once the root canal treatment is finished, you will need to see your general dentist to have a crown or filling placed on the tooth. You are likely to receive a crown if the tooth is discolored or if it is used for chewing. The purpose of the crown is to prevent the tooth from breaking in the future.
Measuring and Cleaning the Root Canals
First, your dentist or endodontist will numb the area around the tooth. You also may receive sedation, such as nitrous oxide. Your dentist also has other ways to reduce your anxiety. Before your first appointment, ask what is available.
The dentist will make a hole in the top or back of your tooth to get to the pulp chamber. He or she will remove some of the diseased pulp.
Then the root canals have to be measured. Your dentist needs to know how long the canals are to make sure the entire canal is cleaned. He or she also needs to know how much filling material to put in the cleaned canals.
To measure the root canals, dentists use X-rays or an electric device called an apex locator. For an X-ray, your dentist will place a file into the canal and then take an X-ray. An apex locator measures a root canal based on its resistance to a small electric current. Many dentists use both methods.
After the canals have been measured, your dentist or endodontist will use special tools to clean out all of the diseased pulp. Then the canal is cleaned with antiseptic. This helps treat and prevent infection. All the canals within a tooth must be cleaned. Teeth have different numbers of canals:
- The top front teeth have one canal.
- The bottom front teeth have one or two canals.
- The premolars have one or two canals.
- The molars have three or four canals.
The location and shape of the canals can vary quite a bit. Some endodontists look inside the tooth with a microscope to make sure all the canals have been cleaned out.
Once the canals have been thoroughly cleaned, the roots are filled. A temporary filling is then placed over the tooth. The top of the tooth should then be covered with a permanent filling or crown. The temporary filling you receive is not meant to last.
In most cases, the tooth will need a crown. A crown will help to restore the tooth's strength and protect it from cracking. If a crown is indicated it should be placed soon after having root canal treatment.
The pulp that was removed during root canal treatment is the part that responds to temperature. Your tooth will no longer be sensitive to hot or cold after the root canal is treated. There still are tissues and nerves around the tooth, however, so it will respond to pressure and touch.
After Root Canal Treatment
As with most invasive medical or dental procedures, complications can occur. Here are some possibilities.
Sometimes when a root canal is opened for treatment, the oxygen in the air will trigger some bacteria to start growing. This causes swelling and pain.
Blood vessels enter the tooth through a small hole at the bottom of the root. Sometimes during a root canal procedure, bacteria are pushed through this hole into surrounding tissue. If this happens, the surrounding tissue will become inflamed and possibly infected. This can be treated with painkillers and sometimes antibiotics. However, it may be painful until it clears up.
A root canal treatment can puncture the side of the tooth. This can happen if a canal is curved or hard to find. The tools that the dentist uses are flexible. They bend as a canal curves. Sometimes they bend at the wrong time and make a small hole in the side of the tooth. If saliva can get into the hole, it will have to be filled. Sometimes, the tooth has to be removed. If the hole is far enough under the gum that saliva can't reach it, the hole may close on its own.
Finding root canals can be difficult. If all of the canals aren't found and cleaned out, the tooth can stay infected. This also can happen if a canal isn't measured correctly and pieces of infected or inflamed pulp are left near the bottom. In this case, the root canal procedure would have to be done again. Occasionally, root canals have branches that the dentist's tools can't reach.
The tip of a file may break off inside the tooth. If the canal is clean, your dentist can leave the piece of file in the tooth. But if canal is not completely cleaned out, the file piece may have to be removed. Sometimes this can be done from the top of the tooth. However, in some cases, the file can only be removed through a surgical procedure called an apicoectomy. A small cut is made in the gum so the dentist can get at the root of the tooth. The dentist shaves off the bottom of the root and gets into the canal from the bottom to remove the file piece.
In most cases, you will not have any pain during a root canal procedure. Your dentist will numb your tooth and the surrounding area. Let your dentist know if you are feeling any pain during the root canal. Some people fear the numbing shots more than the root canal treatment itself. Today, numbing gels and modern injection systems have made injections virtually painless. If it does hurt when you are getting an injection, let your dentist know immediately. He or she can change the way the injection is given to avoid causing pain.
Pain, or the Lack of It
The prognosis is very good for extrinsic stains. Intrinsic stains may be more difficult or take longer to remove.