“What causes a root canal to get infected?”

Bacteria. Generally, this occurs when the root canal pulpal tissue has died and invasive bacteria can feed off this tissue. This process is similar to gangrene.

Bacteria

Many things, could be if you didn't get the crown on the tooth, or if there is another nerve left in the tooth, or if you waited too long to get the crown done, or can just happen.

Rev. Dr. Laurentis Barnett

First of all, you should ask whoever diagnosed that you have a root canal that is infected - they owe you that explanation. There are multiple reasons a completed root canal can get infected - one of them is because the tooth may not have had a final restoration that was secure enough to keep bacteria out of the system and the bacteria traveled into the system from the mouth (a well-fitting restoration does not allow this to happen). Another reason could be if the system was multiple canals, it might not have been possible to locate, clean and fill all the canals, resulting in bacterial not being adequately cleaned out of the system. Also, if the root canal filling material did not fill the system 100%, then some residual bacteria could have resided in part of the canal and not dealt with before finishing the treatment. It is rare to have a well-treated root canal fail unless the restoration was inadequate.
Hope this helps.

Dear Patient,

There are many reasons for RCT infection: preexisting infection which was never cured - incomplete endo treatment means that bacteria was never removed fully from apex while tooth was treated - or infection was missed by treating dentist if rubberdam was not used.

An infection in a canal inside a root says bacteria have gained access to the canal. The question is, how did they gain access? There are two principle ways they gain this access. The most common way is through a pathway between the oral cavity and the canal. The most common way for this to happen is a deep cavity. A cavity is an infection of a tooth. This infection gets into the canal. The other way is rather unusual. Bacteria are not supposed to be in the blood stream. If they are, they can infect a weakened canal. If you never have a cavity, it is probable you will never have an infected canal. The book GROWING A HEALTHY CHILD, SECRETS FROM A WISE OLD DOC clearly shows how you can reduce your risk of a cavity to nearly zero.

Unfortunately, sometimes existing root canals can get infected. This happens due to any number of reasons, including recession of the gums, the space between the crown and the tooth structure, or that the infection before having the root canal was so big that it was never able to completely heal. The most common reason why existing root canals become infected is due to not having a crown placed on the tooth after the root canal.

Ultimately, this is something you need to discuss with your general Dentist so they can evaluate and treatment plan accordingly.

Usually the tooth was not restored properly. Most root canal treated teeth need to have a crown placed. Or, the original root canal was not properly done.

Hello,

Root canal procedures are usually around 98% successful. However, even with this high chances of success 2 out of every 100 root canals fail. A broken tooth after a root canal does not constitute a failure of a root canal. This means that most times when a root canal fails, it is due to what is termed re-infection. Re-infection of a tooth that has had a root canal comes in two different ways; new bacteria making it past the root canal sealant or old bacteria that have laid dormant re-activating. Understanding what happens during a root canal procedure is the best way to learn how a tooth with a root canal gets re-infected. First the dentists accesses the canals of the tooth, then they are cleaned and the organic matter (nerve and blood vessels) are removed from the canals as well as any bacteria that got in there. The canals are shaped a little and then filled with a material sealing off each canal. Re-infection of tooth means that bacteria have gotten into the the sealed off canals and stimulated the immune system. This means that either new bacteria from the mouth have gotten into the tooth and migrated past the sealed canals (it does happen) or the original bacteria has formed a spore (bacteria equivalent of hibernation) and then reactivated stimulating the immune system. Either way the canal system needs to be cleaned again or the tooth would need to be removed (extracted).
Hope this helps.

My best to you!

William F. Scott IV, DMD