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Root Canal Retreatment

Feb 26, 2021

What is endodontic retreatment?

Root canal retreatment procedure at Kipnis Dental Clinic in Brooklyn

Endo-dontics is the term used in dentistry to describe clinical work done inside the tooth (i.e., endo = inside; dontic = tooth). Teeth are made of a hard 'shell' but internally contain a highly specialized soft tissue called the dental pulp. The core of the dental pulp is located in a chamber in the center of the tooth's crown, and extensions of this soft tissue connect it with major blood vessels, nerves, and lymphatics through small canals located in the tooth's roots. Root canal is the common term used to describe the clinical removal of the pulp, and its projections into the dental roots. This is done when the pulp is no longer alive or causes severe pain due to infection.



When the pulp gets infected, it reacts with an immune response similar to any soft tissue in our body. This immune response causes inflammation in an attempt to fight the infection. Unfortunately, the dental pulp is located in a solid chamber that can not expand to allow tissue expansion. Therefore, the inflammatory response ends up causing severe pain and blood-flow loss. In short, the pulp has no means to fight infection, as other tissues do, and needs to be removed to reduce pain and restore the patient's oral health. Once the pulp chamber and the roots are clean, the dentist uses a series of tools to make the root canals a little wider to allow their sealing with a biocompatible material. Root canal treatment is often used as a last resort to avoid teeth extraction.


Unfortunately, not every root canal treatment is successful and, in some cases, fails, causing pain or discomfort to the patient. Root canal retreatment can be described as the process by which a dentist accesses the tooth's internal structure to remove an already treated pulp chamber and root canal system. 

Who performs a root canal retreatment?

Tooth crown with a root canal already performed on the tooth at Kipnis Dental clinic in Brooklyn NY

Endodontists are specialized dentists who are experts in this field. Root canal retreatment can be challenging and usually requires a comprehensive clinical evaluation. Furthermore, endodontists typically have access to more specialized equipment (i.e., dental microscopes or dental cone-beam CT scanners) that can offer essential information regarding the cause of treatment failure. Careful identification of the possible cause of root canal treatment is the most critical factor during retreatment. If the dentists do not address the root (no pun intended) cause of the problem, it is likely to persist.


Root canals are an excellent alternative to prevent tooth loss. Unfortunately, not every endodontic treatment is entirely successful, and retreatment might be required to restore the patient's oral health. Specialized dentists, i.e., endodontists, are the dental practitioners with the most training and experience when performing a root canal retreatment. If done correctly, retreatment has the same success rate as regular root canal treatment.

When is retreatment needed?

The following are the most common reasons for recommending root canal retreatment:

  • When proper disinfection protocols have been violated - the main objective of root canal treatment is to eliminate infected content from the root system; if appropriate disinfection protocols, including the use of absolute isolation, are not followed, the likeliness of that being the cause of post-treatment pain is high.

  • When there is a missed canal - teeth, especially morals and premolars, often have multiple roots and multiple root canal systems. In some cases, roots themselves have numerous root canals. If the dentist is able to identify untreated canals, this is an excellent reason to try retreatment.

  • Coronal leakage - coronal leakage refers to the presence of bacteria or pathogens inside the tooth chamber of an endodontically treated tooth. When this happens, bacteria have access to the material filling the root canals, and, with time, this can compromise the integrity of the entire tooth. Since it is difficult to know to what extend the endodontic treatment has been compromised in these cases, it is wise to choose endodontic retreatment as a viable option.

  • If apicoectomy can not be performed - apicoectomy refers to an alternative treatment that, similar to endodontic retreatment, can be used to save a tooth from being extracted. In this case, the affected root is accessed surgically, and only its tip and any infected tissue around it are removed. The remaining root is disinfected internally and sealed. In some cases, this alternative treatment might be the best clinical choice for the patient. Unfortunately, not all cases are compatible with an apicoectomy, which leaves retreatment as the only teeth-saving choice.

Retreatment success rate.

root canal retreatment at kipnis dental clinic in brooklyn ny

The success rate of root canal retreatment is lower than the initial root canal treatment's success rate, which is around 89%. The success rate of root canal treatment, in general, is related to how effective and efficient the dentist is at removing the canal's content (i.e., infected pulp tissue) which is the original cause of the problem. This process is a little more challenging in the retreatment case because the initial treatment's dental materials mask the involved bacteria and biofilm. Arguably, if the dentist can remove all the infectious content, including the original root canal's dental material, the retreatment success should be similar. Another important consideration is that retreatments are often done in cases where the initial treatment failed, which means that these cases might be of a higher degree of complexity from the very beginning. Finally, dentists facing the challenge of retreatment might have to address or correct technical, iatrogenic, mistakes made by the clinician who performed the original treatment. At Kipnis Dental we frequently see patients coming in who’ve had botched root canal retreatments from other dental clinics in Brooklyn. 

Microbiological characteristics

The micro bacterial population causing endodontic issues after an original treatment is significantly different. Studies have shown that post-endodontic treatment infections are often characterized by pathogens that are never the cause of the original disease. In many cases, these alien bacteria are introduced into the teeth canal system during treatment and are often a consequence of improper use of dental isolation techniques. Dentists need to always follow proper root disinfection protocols (i.e., sodium hypochlorite and ultrasonic vibration) and adequate isolation techniques during any endodontic procedure, especially during retreatment.

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