If you have ever had a discussion with friends or family about dental work before, then chances are that you have heard a little something about a little thing called laughing gas. While laughing gas (nitrous oxide) may certainly help calm a fearful or anxious patient, it is not indicated for use on every patient and there are some important things to consider first. Fear not, though, laughing gas has an extremely safe track record and there have never been any reported deaths or severe complications associated with its use when utilized at the standard concentrations 6.
Let's first talk a little bit about what laughing gas is to better understand its indications for use and what it does to our bodies. Nitrous oxide is a combination of nitrogen and oxygen that, when inhaled, enters the lungs and then the bloodstream and can make a patient feel more relaxed, calm, distracted, and even feel tingly or "floaty". This Happy Air, as many dentists call it, does not put a child to sleep or take away their ability to interact with their surroundings or even numb or anesthetize their body. What it can do however, is calm and distract a patient enough to be able to get a dental procedure done without having an unfavorable experience.
As nitrous oxide is rapidly displaced from the lungs and bloodstream (2-3 minutes), it is a quick acting medication both with it's onset and with its removal from the body 1. Because of this, at normal concentrations laughing gas is a very safe option for use with dental procedures - both with children and adults. Just as with many safe medicines however, there are some people that should avoid using nitrous oxide and this is what we will discuss today.
Genetic Mutations And The MTHFR Gene
One very important thing to consider is how a person's body can metabolize nitrous oxide - or how it can interact at the cellular level. If you or your child has any known genetic mutations, especially a known MTHFR mutation nitrous oxide and other anesthetics may not be safe to use. In the typical process of ridding the body from anesthetics, the products are broken down in order to leave the body - in the case of the MTHFR gene mutation the enzyme necessary to break down the anesthetic is defective. This leads to an accumulation of the anesthetic chemicals in the body and bloodstream which can lead to serious side effects such as neurotoxicity, cardiac concerns, and long term effects (cite and fact check). If your child has any known genetic mutations, be sure to discuss this with your pediatrician and dentist prior to using laughing gas.
Asthma And Respiratory Virus Status
In a patient that has very active asthma or respiratory viruses the capacity of the lungs to maintain enough oxygen is impaired. At typical levels of nitrous oxide use for dental procedures, patients are able to maintain more than enough oxygen in their bodies for normal function. In a patient that already has a limited oxygen supply due to asthma, bronchitis, or pneumonia the lungs may not be able to ventilate the body well enough when nitrogen is introduced into the bloodstream leading to varying levels of hypoxia 2. This is, of course, a dangerous side effect of laughing gas and should be taken seriously. It is also important to note that if your child also has a fairly stuffy nose, nitrous oxide may still be safe to use but likely won't be effective as the ability to inhale it into the body is impaired. A stuffy nose may also make the child feel like they are unable to breathe when the nose piece is placed on the child and therefore it may be best to reschedule the procedure for a day when congestion is not present.
Cancer And Medication History
Of course all medications should be discussed with your dentist for possible procedure interactions, but Bleomycin therapy history is especially important to note to your dentist before the use of laughing gas. Bleomycin is a type of medication used to treat certain patients with cancer and it is possible that additional oxygenation to the body (as is the case with nitrous oxide use) can lead to pulmonary toxicity in patients undergoing this medication therapy 4. This type of pulmonary condition called interstitial pneumonitis can severely damage the lungs and be dangerous for the patient. If your child has a history of cancer or more importantly is currently undergoing cancer treatment, this should be discussed in detail with your doctor prior to receiving nitrous oxide.
Vitamin B12 And Other Vitamin Deficiencies
While the exact mechanism is certainly complicated to understand, laughing gas has been shown to reduce the amount of active B12 in the body which in turn can lead to both genetic and protein abnormalities 5. For this reason nitrous oxide is recommended to be avoided in the first trimester of pregnancy (see below) and also in those patients who are naturally low in vitamin B12 or other nutrients. Patients that may naturally be low in these vitamins are those that have GI disease, those that have specific types of anemia (the pernicious variant), or those that are malnourished for any reason. It should be noted that those patients that are healthy with no other medical concerns do not have an issue with the temporary depletion of the Vitamin B12 when using nitrous oxide.
Ear Infections And Inner Ear Concerns
The inner ear is one of the most common areas in the body to have sensitivity to pressure (think ear popping and Swimmer's Ear pain). As nitrous oxide is known to increase pressure in the air spaces of the body 2. Most patients have absolutely no problems with this increase of pressure because the body is able to regulate it on its own. However anyone that has ear concerns or the inability of the ear to release pressure on its own (due to ear infections, ear surgeries, eustachian tube dysfunction) can suffer from serious side effects such as hearing changes or even rupture of the ear drum in extreme cases 2. For the same reasons, anyone who has recently had eye surgery should avoid nitrous oxide use as well. If your child has any ear concerns or ear infections, it is best to discuss the use of laughing gas first with their pediatrician/ENT doctor and dentist prior to using it for dental procedures.
Chemical Dependence and Psychological Health
While occasional and short term use of nitrous oxide is not known to produce psychiatric episodes or disorders, it should be used with caution in anyone with a known psychological condition since laughing gas is known to alter the psychological state 2. In addition to this, nitrous oxide is also known to induce a euphoric state in the patient so the use should also be avoided in those who have any history of chemical dependency 2. Any concerns related to the patient's psychological well being should be addressed with the patient's treating physician.
Though data on this occurrence is somewhat limited, it is advised that patients avoid nitrous oxide in the first trimester of pregnancy as there may be an increased risk of spontaneous miscarriage 3. One study did show that while there may be a slightly elevated risk of miscarriage however this study was centered around female dental assistants who were exposed to laughing gas several times per day. No reason has been confirmed as to why nitrous oxide may increase this risk however many have speculated this could be due to the depletion of Vitamin B12 as mentioned above 5.
To read the guideline on nitrous oxide use for pediatric dental patients in its entirety visit the PDF guidelines section of the AAPD.
1.American Academy of Pediatric Dentistry Council on Clinical Affairs. Guideline on use of nitrous oxide for pediatric dental patients. 2018.
2. Duncan GH, Moore P. Nitrous oxide and the dental patient: A review of adverse reactions. J American Dental Association. 1984; 108(2):213-9.
3. Rowland AS, Baird DD, Shore DL, Weinberg CR, Savitz DA, Wilcox AJ. Nitrous oxide and spontaneous abortion in female dental assistants. American Journal Epidemiology 1995;141(6):531-7.
4. Fleming P, Walker PO, Priest JR. Bleomycin therapy: A contraindication to the use of nitrous oxide - oxygen psychosedation in the dental office. Pediatric Dentistry 1988;10(4):345-6.
5. Sanders RDB, Weimann J, Maze M. Biologic effects of nitrous oxide: A mechanistic and toxicologic review. Anesthesiology 2008;109(4):707-22.
6. Wilson S, Gosnell E. Survey of American Academy of Pediatric Dentistry on nitrous oxide and sedation: 20 years later. Pediatric Dentistry 2016;38(5):385-92.
7. Selzer R, Rosenblatt D, Laxova R, Hogan K. Adverse effect of nitrous oxide in a child with 5, 10-methylene-tetrahydrofolate reductase deficiency. New England Journal of Medicine 2003;349(1):45-50.
Dr. Mikaeya Kalantari has been a practicing pediatric dentist for over 7 years working in both the children's hospital setting and private practice. She has had a wealth of experience treating children of all ages, and medical conditions. When it comes to serving children, she feels the importance of communication between the dentist and parent can not be emphasized enough. Dr. Kalantari practices in her family owned dental office in Mission Viejo, California.