Dental Nitrous Oxide System

Everything there is to know about dental nitrous oxide systems

The combination of oxygen and nitrous oxide in a nasal inhalation delivery, under a maintained pressure, is proven to be the most popular sedation method in dental practice. The sedation effect allows dentists to perform more efficiently with a high functional margin and prevent operation-related anxiety for patients. The dental nitrous oxide system is prevalent in pediatric dentistry because children's reflexes may alter dental procedures, making them more time-consuming for the practitioner. The system provides 100% oxygen saturation at the beginning and at the end of the sedation process, to ensure optimal oxygen saturation.

History of the dental nitrous oxide system

Joseph Priestly was the first one to isolate the (N2O) gas in 1772. Horace Wells, an American dentist, was the one to use nitrous oxide as an anesthetic drug in dental treatment. The very first attempt was done on December 11, 1844, and showed remarkable insensitivity to pain from dental extraction. Half a century later, Maximilian Neu was the first to use rotameters (simple industrial flow meters) for more accurate dosage of inhaled N2O–oxygen mixtures in 1910. Then, in the mid-1920s, the German company known as Draeger Company was the first company to manufacture a line of N2O anesthesia apparatus, which had a delivery system that was equipped with a carbon dioxide absorber.

Indications to use nitrous oxide system

The primary use of nitrous oxide systems is the induction and maintenance of conscious sedation in dental procedures. This benefits the patient by reducing anxiety, producing analgesia, and enhancing communication between the patient and the dentist throughout the treatment procedure.

Conscious sedation in reducing procedure-related anxiety is mainly used in pediatric dentistry; because children are most exposed to irritability and fear from dental procedures. The gas delivery system ensures maintained sedation by delivering 70% N2O and 30% O2, allowing 100% oxygen saturation at the beginning and the end of the treatment.

The main indications of N2O inhalation:

  1. Reduce and eliminate anxiety.
  2. Reduce sudden untoward movements and reduce physical reactions to the procedure.
  3. Increase tolerance for long treatment sessions.
  4. Produce analgesia and raise the pain reaction threshold.
  5. Enhance communication between the patient and the practitioner.
  6. Reduce the need to gag the patient.
  7. Potentiate the effect of other sedatives.
  8. Facilitate the treatment for mentally compromised or physically disabled patients.

Complications of using dental nitrous oxide system

The dental nitrous oxide system has an excellent safety profile when administered with the right concentrations and flow. However, acute and chronic adverse effects may arise during its application, especially with the exposure during long treatment sessions, and the lack of titration during induction and stoppage of the administration.

The acute adverse effects include:

  1. nausea       
  2. general fatigue      
  3. dizziness   
  4. vomiting         
  5. shivering   
  6. excessive sweating

Chronic Adverse effects

The exposure for a long time may cause a deprivation in Vitamin B12, causing anemia. Vitamin B12 deficiency causes symptoms related to the central nervous system, like peripheral neuropathy and nerve damage. But it is known that the drop in vitamin B12 level is likely to be corrected spontaneously once the exposure to the nitrous oxide gas is terminated.

Limitations to use N2O gas

  1. Patients who have a chronic vitamin B-12 deficiency
  2. People who have a history of any psychological disorder or emotional disturbance.
  3. Patients who are asthmatic or have chronic obstructive pulmonary disorder (COPD).
  4. Female patients in their first trimester of pregnancy.
  5. People who have active upper respiratory tract infections.
  6. People have a recent middle ear disturbance or surgery.
  7. Treatment with Bleomycin sulfate.

Alternative Instruments

There are no similar gas delivery systems that apply the same method of conscious sedation as a dental nitrous oxide system. However, doctors may use such pharmaceutical medications before the treatment sessions as anxiolytic, analgesics, and hypnotics.

General specifications of dental nitrous oxide system

The Accutron N2O system consists of the following main functional parts:

  1. Flow-meter
  2. Reservoir bag
  3. Corrugated tube
  4. Vacuum control assembly
  5. Gas delivery and vacuum tubing
  6. Nasal hood

Safety features in the Accutron N2O system

There are mainly two major N2O delivery systems, the portable tanks on yoke stands that can be wheeled between operating units, and the central fixed tanks that are connected with a divergent system that can supply several operation units. 

N2O delivery systems are typically configured to a delivery of 70% nitrous oxide and 30% oxygen saturation. Also, the system should have the ability to deliver 100% of O2 saturation at the beginning and end of the administration.

There are safety features that should be included in any delivery system to ensure the least events of adverse reactions and complications; these features include:

  • Emergency air inlet

An emergency inlet is structured to be closed when gases are administered to the patient. They should be opened to allow ambient air to enter the system when the oxygen supply turns off at any point during the administration. This emergency air inlet allows the patient to continue breathing through the nasal hood or the face mask.

  • Oxygen fail-safe system

The oxygen fail-safe system is structured to automatically turn the nitrous oxide system off when oxygen saturation fails at any point in the administration. The average delivery system delivers a minimum of 2.5 to 3.0 liters of oxygen per minute; this amount ensures that the oxygen concentration never falls below 30% through the administration time. 

  • Alarms

This safety feature is an audio or visually alarming attachment that gives alarm messages whenever a problem occurs in the delivery system.

  • Color Coding

Color codes are standardized nationally for each gas tank, knobs, and hoses, for example, the green for O2 tanks and blue for N2O tanks. 

 Quick connect for positive-pressure oxygen.

This safety feature allows the practitioner to shift quickly to positive pressure oxygen in case of emergencies like "augment cardiopulmonary resuscitation."

How dental nitrous oxide system works

Nitrous oxide-oxygen mix consists of portable tanks, attached to a flow-meter device which controls the pressure and the concentration of the gasses. The mixing process takes place in a reservoir bag. Then the gases are pushed to a vacuum tube assembly via a corrugated tube. The last part is a nasal delivery device called "nasal hoods." This device is directly attached to the nose, delivering the gas directly to the respiratory system. The nitrous oxide then gets absorbed and distributed by the alveoli in the lungs, and reaches the steady-state in the blood, which gives the needed sedative effect.

The average accepted flow rate for most patients is five to six liters per minute. This flow rate could be adjusted due to the observation of the reservoir bag during the administration. The reservoir bag should shrink to one-third full after inhalation and expand to two-third full after the patient exhales, and the bag is filled with mixed gas. An over-inflated on distended bag indicates too high gas flow, and it should be reduced. An under-inflated or collapse bag indicates low gas flow and should be increased.

The nasal hood has several characteristics that help patients inhale and exhale easily during the procedure. The double hood enhances the elimination of carbon dioxide from the system. It minimizes ambient N2O, and the transparent outer hood expands the clinician field of the view and provides easier access to the patient's mouth. A capnography device could be attached to the nasal mask to help directly measure the exhalation volume and monitor the carbon dioxide concentration.

Market Leaders 

  1. Crosstex International, Incorporated
  2. Porter Medical Instruments
  3. Tecno Gaz Industries
  4. Prime Dental Supply Incorporated


The procedure-related anxiety is a significant challenge in dental practice; most of the patients experience some level of anxiety or irritability during dental treatments. Hence, it becomes very hard for them to communicate throughout the procedure. The conscious sedation concept allows the patient to be aware and fully participate in the treatment while providing a moderate sedation level, which helps the patient keep calm and reduce reflexes and untoward reactions.

The Nitrous oxide system is a closed circle. The patient receives 70% of N2O gas and 30% of oxygen gas during administration, controlled by a flow-meter device, and delivered by a nasal hood. The system is secured by multiple safety features that automatically control flow and shut down the administration in case of emergency. Also, the system should deliver 100% of O2 saturation at the beginning and the end of the administration to meet the ADA criteria. The administration and monitoring should be run by well-trained individuals and under the supervision of licensed practitioners to ensure the highest safety and functionality standards.

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