Many patients come to us after they’ve been told they have a symptomatic, or failing, root canal. They are told they need a surgery called an apicoectomy, an outpatient procedure to prevent complications involving the mouth and jaw. 

What we’ve seen is that in many of these cases, the root canal is not failing. It may be painful or just sensitive, but those symptoms don’t always indicate that a root canal is failing.

A root canal-treated (RCT) or root-filled tooth is one in which the dental nerve, commonly called the pulp, is intentionally removed and is filled with an inert material called gutta percha.

Once an RCT is performed, the tooth must be restored with a post and a crown. These will strengthen the tooth and prevent a crack or fracture from developing after treatment. A good analogy is a tree branch. When it’s alive, it flexes or bends when pressure is applied. On the other hand, a dead branch, like an RCT, will break under the same stress.

With recent improvements in technology, root canal success rate are estimated between 50% and 80%.

That said, as many as one tooth in seven may be classified as a root canal failure, In addition, many of those failures are chronic, that is, producing no radiographic signs or pain symptoms to indicate failure.

The reasons for root canal failure are not entirely clear. Failure may occur predictably on teeth that have a poor clinical result. This might be caused by doctor error, the inability to clean out all the canals, or the failure to place a post or crown after the root canal.

Beyond this, a root canal, even if well-performed, can still fail. Research has found four major causes of root canal failure:

• Tooth or root fracture
• Infections including bacteria (primarily enterococcus fecalis, etc.), viruses, and fungus (candida, etc.).
• The body’s reaction to root canal materials, microorganisms, and cements, which inadvertently are pushed past the tooth into the bone.
• Cysts

CAN A FAILED ROOT CANAL HAVE A SYSTEMIC EFFECT ON THE BODY?

A tooth is an open biological system that communicates with the body, whether alive or dead following a root canal. As a result, the question of systemic effects on the body becomes an important issue.

Such concerns were raised when studies were done on patients with acute myocardial infarctions (heart attacks). One study focused on chronic dental infections, that is infections that produced no visible or symptomatic signs (Matilla et al, 1989). A follow-up study was performed to determine the correlation between chronic (silent) dental infections and coronary atherosclerosis (Matilla et al, 1993). Both studies cited leaking bacterial endotoxins from root canals as a potential mechanism for cardiac disease.

Root canal infections also have close access to blood circulation and systemic dissemination (Tronstad, 1992). One study, performed during root canal therapy, isolated bacteria from the blood stream of patients (Debilian,1995). 

That leaves is with a basic question that has yet to be thoroughly investigated. Can root canal failures, which may be as high as one is even treated teeth, seed infection in the body and contribute to systemic disease?

The question regarding the safety of failed root canals may never be adequately answered. Also, the basic question about whether a root canal failure can be determined due to pain is still debated. Pain, as we have discussed, shows little correlation to histological findings. Researchers as far back as the 1960’s have demonstrated that infections can be present without radiographic evidence (Bender and Selzer, 1961, Van der Stelt, 1985; Huumanen and Orstarik, 2002). In fact, one study found infections up to 8mm may be present without any trace of radiographic evidence (Ricucci and Bergenholtz, 2003)

Root canal failure, an issue of systemic proportion, remains a little understood and hotly debated subject.