Success Rate and Outcomes of Root Canal Therapy

Every stakeholder in dental delivery system has different definitions and expectations regarding the outcome and result of root canal treatment. As a patient, you might be concerned about the function and esthetic of the endodontically treated tooth where as your dentist will judge the outcome of a root canal treatment based on the results of clinical and radiographic examinations.

What determines the success of root canal treatment?

Clinical examination and radiographic findings are the most common methods used to evaluate the outcome of a root canal treatment.

Clinical criteria for success:

–          Absence of previous signs and symptoms (such as pain and swelling)

–          Disappearance of sinus tract (communication between pathologic space and skin)

–          The surrounding soft and hard tissues are intact

–          No evidence of radiolucent lesion.

Histologic examination (microscopic study) is another method to evaluate outcome of root canal treatment but this method is not routinely used among dentists.

When should I schedule for an evaluation visit after my root canal treatment?

It is recommended that you should schedule an evaluation visit within 6 months. The root canal treatment is considered unsuccessful if the size of radiographic lesion remains unchanged or has increased after a year. European Society for Endodontology indicates that clinical and radiographic follow up should continue for 4 years.

What is the success rate for root canal treatment?

Root canal therapy is not always successful. It has been reported that the success rates for root canal therapies are between 80 to 90 percent. If failure of root canal treatment does occur, it is important for the dentist to understand the cause of failure so that he can decide upon the future management of the tooth. Most common reason of a failed root canal treatment is due to presence of microorganisms.

What can cause root canal treatment to fail?

The failure of root canal therapy can be due to:

Preoperative errors:  Misdiagnose and incorrect treatment planning can cause failure of root canal treatment. Diagnosis should be based on: history and current signs and symptoms, radiographic evaluations and tests.

Operative errors: Failure of root canal treatment can be due to failure of the dentist to create a straight line access (root canals may be missed out, inadequate cleaning and shaping and obturation)

Quality of root canal filling:  Overobturation of root filling can lead to inflammation of your tissues.  Voids in a root canal filling indicate empty spaces which allow tissue fluid (source of nutrient for bacteria) to enter the root canal and cause reinfection of the system.

Coronal leakage : Failure of the dentist to provide a good coronal restoration after your root canal

What are the treatment options of for a failed root canal treatment?

–          Retreatment – Retreatment involves removing the obturation material inside your existing root canal and redoing the entire root canal process.  However, endodontically treated tooth has been reported to have a success rate of 70%. Retreatment of endodontically treated tooth can be complicated by presence of obstruction such as root canal filling material.

–          Endodontic surgery – Surgery is performed in order to save the tooth. It is always considered as a last resort to save your tooth because it does not deal with the entry of microorganisms into your teeth.

–          Intentional replantation and autoreplantation:

Intentional replantation is done by extracting the tooth and your dentist will perform root end surgery out of the tooth’s socket.

–          Autoreplantation:  Autoreplantation is done by transferring a tooth from one socket to another socket. Both procedures require careful management and case selection in order to have long term success.

–          Extraction of the particular tooth without replacement is the cheapest option.

–          Fixed partial denture. Dental bridges are good alternatives to replace missing tooth. However, they are prone to failure too if they are not well maintained. According to some surveys, small conventional bridges can last around 20-40 years where as larger conventional bridges can last for 10 to 30 years. Read for more information on the prognosis of dental bridges.

–          Single tooth implant.  However they are expensive and the prognosis depends on several factors such as bone density and your periodontal condition. Success rate for single tooth implants have been reported between 76% and 100%.


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