Why you need a root canal?
When a tooth becomes decayed or fractured, the bacteria eat their way through the enamel and dentin layers until they reach the pulp tissue. Once here, they cause the pulp tissue to break down, causing destruction of the nerves and blood vessels within the pulp. As the tissue breaks down, an infectious process starts within the pulp and eventually the nerves and blood vessels die. Pressure from this infectious process builds up within the tooth, usually causing pain, and eventually an abscess develops at the root tip. Until this degraded tissue is removed from within the tooth, this painful infectious process continues.
All teeth have three main layers: the outer enamel layer on the top of the tooth or the cementum layer on the root, the inner dentin layer and the pulp. The pulp is the innermost layer within the roots of the tooth containing the nerves and blood vessels that supply the tooth. The blood vessels provide nutrients to the tooth, the nerves provide sensation. When the pulp is intact, the tooth is vital and healthy.
Root canal treatment
Root canal treatment is performed on teeth where the nerve tissue within the roots has deteriorated, creating an infection. Within the roots are tiny canals where the nerve is located. When the nerve tissue degenerates, these tiny canals must be located, thoroughly cleaned and then sealed with a filling material. In some cases, the canals cannot be located or are constricted, preventing them from being fully cleaned and filled. In this example, the molar tooth has had root canal treatment. One of the canals has not been filled to the root tip, leaving a space in the canal which can become infected again.
A second attempt was made on this molar tooth to try to seal the canal all the way to the root tip. The first filling within the root canal was removed and the canal was located, cleaned and refilled, all the way to the tip of the root. In this specific situation, the retreatment was successful, however in some cases, the second result is the same as the first.
When the canals within the root cannot be thoroughly cleaned and sealed, the chance of re-infection or loss of the tooth is greater.