Experiencing an abscessed tooth years after you've had a root canal can be a puzzling and alarming experience. You assumed that the root canal and crown took care of the initial problem. This is not always the case, though. That tooth may still be susceptible to an infection.
Inadequate Root Canal
The goal of root canal therapy is to completely clean the inflamed or infected tissue from the root and then totally seal the space to the tip of the root. But debris left in the end of the canal can harbor bacteria that may cause an infection. Likewise, if the root canal filling is extruded beyond the root apex while it is being placed an infection may develop according to the Journal of Dental Research.
Missed Canal
Most teeth are predictably normal when it comes to how many root canal spaces it contains. For example, an upper front tooth has one canal in virtually every case. But there are variations. A missed canal can lead to an infection years after treatment and cause the tooth to require further treatment, according to the American Association of Endodontists. Because a dental x-ray is a two dimensional image of a three dimensional tooth extra canals are not always detected. The recent employment of microscopy during root canal therapy has greatly reduced the occurrence of this problem.
Cracked Root
The roots of a tooth are made slightly more brittle by the root canal treatment. Although the immediate placement of a crown helps protect the root from fracturing during chewing it may still occur years later. It is rare but possible that the root canal treatment itself can cause a fracture in a root. According to the Cleveland Clinic, a crack in the root may cause a new infection to emerge as bacteria are able to enter and remain within a root. Cracks in roots are practically impossible to detect at the time of root canal treatment and are only confirmed after a tooth that will not heal is extracted.
Leaking Crown
The root canal-crown combination seals the tooth from bacterial leakage from top to bottom. Over time this seal may be broken due to dental decay. A leaking dental restoration permits bacteria to invade the filled root canal according to the College of Diplomates of the American Association of Endodontists. Once this happens the root is no longer sealed and bacteria are harbored inside the tooth and its roots. Eventually this will lead to an infection of the tissue around the tooth.
Gum Abscess
Root canal therapy removes the soft tissue from inside the tooth and seals it internally from developing further infections. Externally the gum is attached to both the tooth and bone. This attachment is protected from bacterial invasion with daily brushing and flossing. The development of an abscessed tooth years after a root canal and crown can develop in the gum tissue without proper oral hygiene.
Prevention/Solution
Proper oral hygiene and regular dental checkups are the best defenses against future infections after a root canal and crown. According to the American Association of Endodontists, if an abscess does occur there are two possible treatments to save the tooth: retreatment of the root canal or surgical removal of the infection. At the first sign of a toothache dental care should be sought for appropriate treatment including the possible administration of antibiotics.
