HomeHealth articlesroot debridementSide Effects of Using Sodium Hypochlorite as a Root Canal Irrigant

Sodium hypochlorite is used to irrigate the root canals during root canal treatment. Forceful irrigation can result in sodium hypochlorite accidents. Learn about the causes of sodium hypochlorite accidents and ways to prevent them.

Medically reviewed by

Dr. Chithranjali Ravichandran

Published At June 19, 2015
Reviewed AtOctober 6, 2022

What Is Sodium Hypochlorite?

Sodium hypochlorite (NaOCl) can be commonly found in a dentist's office. It is used as an irrigant during root canal treatments as it dissolves organic soft tissue of pulp and predentin. It is usually used in a dilution of 0.5 % or less. Higher concentrations of sodium hypochlorite are cytotoxic. It has a foul chlorine smell and taste. When sodium hypochlorite extends through the periapex of the tooth and comes in contact with the periapical tissues, it causes acute inflammation followed by necrosis.

What Are the Advantages of Using Sodium Hypochlorite?

  • It has an antifungal property.

  • It helps in the disruption and removal of biofilms (a complex structure containing different colonies of bacteria).

  • It aids in the breakdown of proteins to amino acids and hence has a robust dissolving action on organic tissues and microorganisms.

  • It also aids in hemostasis (bleeding cessation).

What Is a Sodium Hypochlorite Accident?

When sodium hypochlorite comes in direct contact with the periapical tissues (soft tissue surrounding the root apex of teeth), eyes, or extraoral tissues, it is termed sodium hypochlorite accident. If the patient experiences a sudden severe pain during the root canal procedure, we must suspect a sodium hypochlorite accident.

What Are the Signs of Sodium Hypochlorite Toxicity?

The signs and symptoms differ for each site and include the following:

  • Edema (swelling with fluid accumulation).

  • Ecchymosis (discoloration of the skin due to bleeding from underneath).

  • Profuse bleeding from the root canal of the tooth.

  • The patient may experience the smell of chlorine and severe pain.

  • Burning sensation in the eyes.

  • Paraesthesia (characterized by numbness and burning sensation in the affected area).

What Are the Effects of Sodium Hypochlorite Accident?

Sodium Hypochlorite Accident

The severity of the damage depends on the pH of the solution and the duration of exposure. Also, the exposure site plays a significant role in determining the effect.

1. Periapical Extrusion:

When sodium hypochlorite is extruded beyond the root canal, even a minimal amount, it results in profuse bleeding from the root canal cavity. It also produces rapid swelling of the involved tissues. It is attributed to the ability of NaOCl to damage the blood vessels and the release of histamine. The ecchymosis and edema can involve the affected side of the face, including the eyes and oral cavity regions. In some cases, pain and the affected region's erythema are present. A tingling and burning sensation have also been reported.

2. Contact With Eyes:

When it comes in contact with the eyes, sodium hypochlorite can lead to endophthalmitis. It can lead to severe complications in a few cases, like loss of the eye.

3. Allergic Reactions:

Allergic reactions of sodium hypochlorite cause the following complications:

  • Edema.

  • Urticaria (skin rashes).

  • Shortness of breath.

  • Hypotension (reduced blood pressure).

  • Bronchospasm (construction of the bronchial muscles).

4. Oral Mucosal Damage:

When sodium hypochlorite comes in contact with oral mucosal tissues, it can lead to the development of secondary infections. Also, there is a possibility of swallowing the solution that might lead to further systemic complications.

How Does a Dentist Manage NaOCl Accidents?

1. Periapical Extrusion:

  • Early recognition of the problem - The dentist informs the patient immediately about the accident.

  • Irrigates the root canal immediately with normal saline. This dilutes the NaOCl and reduces the severity.

  • Allows bleeding to occur, which helps flush out the irritants.

  • Reassures the patient that things are under control.

  • Explains to the patient how to manage at home and preferably gives written instructions for home care. It is also essential to monitor the patient on a daily basis.

  • Palliative care - Cold and warm compresses, saline rinses, pain control, prophylactic antibiotics, and steroids if required.

2. Exposure to Eyes:

After a suspected exposure to the eyes, the patient is asked to cleanse the eye with normal tap water or saline. The patient is then referred to an ophthalmologist immediately for further management.

3. Allergic Reactions:

Intravenous administration of antihistamine medications and steroids is the first aid measure to be carried out. It is then followed by rushing the patient to an emergency department.

4. Oral Mucosal Damage:

Initially, the mucosa is washed with water, and appropriate analgesic and antibiotic drugs are given to prevent the occurrence of associated secondary infections. In case of any inhalation or ingestion of sodium hypochlorite, the patient should be immediately sent to the emergency department for preventing and managing complications.

How Can a Dentist Avoid NaOCl Accidents?

  • Always prepare adequate access into the root canal.

  • Good working length: Make sure that the working length is not overextended.

  • Ensure the irrigation needle is placed 1 to 3 mm short of the working length and that the needle is not locked in the canal.

  • Flush the canal slowly with the irrigant by moving the needle constantly in and out.

  • During the procedure, observe if the solution flows out during irrigation.

  • Using irrigant needles with side venting specifically designed for endodontic purposes minimizes accidents.

  • Specialized needles like Luer lock needles (which have a twisted tip preventing accidental removal and injection) can be used.

  • The needle top should be placed loosely inside the canal and should not be wedged.

  • Increased digital pressure should be avoided.

  • In teeth with an open or inadequately-formed apex, the use of sodium hypochlorite should be avoided beyond the coronal two-thirds of the root.

  • Using rubber dam isolation to prevent the exposure of sodium hypochlorite to intraoral tissues.


Sodium hypochlorite has a significant antibacterial property that helps in reducing bacterial infection along the root canal. But it also has its own harmful side effects when accidental contact occurs. By following adequate preventive measures, the incidence of hypochlorite accidents can be entirely avoided. When such a thing happens, it should not be neglected and should be managed immediately.

Frequently Asked Questions


What Is Sodium Hypochlorite Used for in Dentistry?

Sodium hypochlorite is a disinfecting agent which is effective for the disinfection of viruses, bacteria, fungi, and mycobacterium. It is used for irrigating root canals during the root canal treatment procedure as it dissolves the organic tissues of pulp and pre-dentin.


How Do You Dilute Sodium Hypochlorite in Dentistry?

Typically it is recommended to begin with a 5.3 % concentration of sodium hypochlorite. With a 1:1 dilution, a 2.5 % concentration can be obtained. Using one part of 5.25 % sodium hypochlorite with the same volume of water helps achieve the desired concentration.


What Happens if You Swallow Sodium Hypochlorite During the Root Canal?

Sodium hypochlorite is the most common root canal disinfectant used in varying concentrations. The amount of sodium hypochlorite that is used during root canal treatment is very minimal, and the chemical gets diluted with the saliva, so there should be no side effects other than bad taste. But if you feel you have swallowed sodium hypochlorite, you may experience gastrointestinal discomfort, nausea, and vomiting.


Why Is Sodium Hypochlorite Used in the Root Canal?

Sodium hypochlorite can be used as a root canal irrigant during the root canal procedure as it dissolves the organic tissues in the pulp and pre-dentin. It flushes out the loose debris from the root canals.


What Percent of Sodium Hypochlorite Is Used in Endodontics?

Sodium hypochlorite is the most prevalently used root canal irrigant. It is used in varying concentrations. The recommended concentrations include 0.5 %, 1.0 %, and 2.5 %. From a study, it was found that 2.5 % sodium hypochlorite, due to its less cytotoxic effect, is the most suitable concentration for root canal treatment.


Why Do Dentists Use Bleach in Root Canals?

Sodium hypochlorite is used as a bleaching agent during the root canal treatment to clean the canals and pulp chamber of a tooth to dissolve the bacteria if present and to flush out the pulpal remnants.


What Is the Ideal Concentration of Sodium Hypochlorite for Root Canal Irrigation?

The greater the concentration of sodium hypochlorite, the greater will be the tissue damage. If in case the root canals are irrigated without the use of a rubber dam or without proper techniques and instrumentation, then it is recommended to start with a 5.35 % concentration of sodium hypochlorite.


What Is the Common Use of Sodium Hypochlorite?

Sodium hypochlorite has the following uses:
- It is used as a bleaching agent.
- As a disinfectant.
- Sodium hypochlorite has deodorizing properties.
- It is the medication of choice against pathogenic organisms and pulp digestion in endodontic therapy.


How Does Sodium Hypochlorite Kill Bacteria?

Sodium hypochlorite is a strong oxidizing agent, so when sodium hypochlorite comes in contact with bacteria, viruses, or fungi, it oxidizes molecules in the cells of germs, hydrolyzes cell proteins, and kills them.


How Poisonous Is Sodium Hypochlorite?

Sodium hypochlorite is a caustic chemical that requires careful management. If it comes in contact with the tissues, it can injure the tissues. Swallowing or breathing sodium hypochlorite can also cause poisoning. Due to its cytotoxic effects, it can cause complications.


Is Sodium Hypochlorite Safe for Skin?

Sodium hypochlorite is usually not toxic to the skin, but it can irritate the skin, eyes, or any other parts of the body when in contact with the solution. This sodium hypochlorite can become more harmful when mixed with other chemicals.


How Long Should the Canals Be Irrigated Using Sodium Hypochlorite?

To achieve thorough and complete disinfection of the root canal, sodium hypochlorite has to be let inside the canal for at least 30 minutes, and it was also proven that when used for a lesser time, the treatment outcomes had decreased.
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