Out-of-this-world oral health for astronauts

Do you remember what you wanted to be when you grew up? For a lot of people, the allure of space travel is strong, but the requirements to get there can be hard to meet.

There are technically only five requirements to becoming a NASA astronaut:

• U.S. citizenship
• good physical health
• a master's degree in a STEM field
• 1,000 hours of piloting a jet
• a passing mark on the NASA long-duration flight astronaut physical

And as a part of NASA's physical requirements, astronauts also need to have great oral health.

Why astronauts need good oral health

Pressure changes in the atmosphere, like those experienced during launch and landing, can cause pain in untreated cavities.

G-forces during launch creates incredible pressure and vibrations. Weaker dental fillings, crowns and bridges can be dislodged.

Astronauts in space experience an estimated 1% decline in bone mass for every month in space, which can affect teeth, too.

Examinations after returning to Earth or after simulated space slight show changes in oral bacteria that could increase the risk of gum disease

NASA requires meticulous oral screening procedures for astronauts to avoid damage. Astronauts are classified into three categories: Class I, Class II and Class III.

• Class I astronauts have good oral health and aren’t expected to require dental treatment or evaluation for the next 12 months.  

• Class II astronauts have some oral conditions that, if left untreated, aren’t expected to result in a dental emergency within a 12-month period.  

• Class III astronauts have an oral condition that, if left untreated, is expected to result in a dental emergency within a 12-month period.

All astronauts are expected to stay at Class II or Class I status. Only astronauts with a Class I status are considered for the International Space Station — and that doesn’t mean they’re fully cleared!

Astronauts have yearly dental exams to determine which Class they’re in and then more exams 18 to 20 months before launch. These exams include bitewings and panoramic x-rays like the ones you get at your dentist. If their dentist finds any problems, the astronauts must receive treatment at least 90 days prior to launch. Even after all of that, astronauts have to get one final exam to find hidden diseases or unreported injuries at least 30 days before launch.

It might seem excessive, but NASA has good reasons to be cautious.

Brushing teeth on the International Space Station

When astronauts are on the International Space Station (ISS), they follow thorough oral hygiene routines to maintain their hard-won oral health. However, the living space on the ISS is small. It can be difficult to include things you use only once, such as dental floss, and all the water is recycled.

Astronauts adjust their routines from Earth to adapt to life on the ISS. They brush their teeth and then swallow their toothpaste with water since spitting it out isn’t an option. International Space Station Commander Chris Hadfield made an informative video on his morning routine that shows how he deals with the unique effects of microgravity when brushing his teeth.

Treating dental emergencies on the International Space Station

Many astronauts are on the ISS for six months or longer and any dental problems can be difficult to treat. There isn’t enough room on the ISS to keep equipment and materials for specific and uncommon procedures. Problems that can’t be taken care of onboard could result in an astronaut’s early return to Earth. 

NASA recommends (but doesn’t require) that astronauts get their wisdom teeth and appendix removed to avoid the possibility that they’ll cause problems while in space.

Aside from the absence of specific tools, there’s another barrier to oral treatment in space. Space organizations bet on the fact that health emergencies are rare, so they don’t require a member of the ISS crew to have a medical degree.

Instead, there are two crew medical officers (CMOs), regular astronauts who perform medical procedures in additional to their research. And all astronauts are trained to perform CPR in weightless conditions, stitch wounds and pull teeth.

Did you know?

There are no astronauts who hold a degree in dentistry!


Becoming an astronaut takes a lot of work and isn’t going to be for everyone. Even if you’re not planning to go to space anytime soon, brush your teeth and visit your dentist to get out-of-this-world oral health that even astronauts would be proud of!