To make it into space as a NASA astronaut, you have to be smart, fit, between 5'2" and 6'3", and have outstanding oral health.
It's not just to smile for the cameras. Like any other part of an astronaut's body, teeth can be affected by the extreme conditions of space travel.
* During the launch phase, an astronaut must endure a G-force of up to four times their own body weight. Under that incredible pressure and the accompanying vibration, weaker dental fillings, crowns or bridges could become loose or dislodged.
* Atmospheric pressure changes would create great pain where undetected or untreated cavities are present.
* While in space, astronauts can have a serious decline in bone mass, an estimated 1% for every month. NASA calls this degeneration "space bones." Some researchers believe conditions such as periodontal disease can become more prominent with the loss of bone mass.
* Astronauts examined after their return to earth or after a simulated space flight showed an increased risk for periodontal diseases based on changes in oral bacteria. Under these circumstances, any pre-existing condition would worsen.
To avoid such risks, NASA requires meticulous oral screening procedures for astronauts. Applicants are classified into three categories:
* Class I astronauts have good oral health and are not expected to require dental treatment or evaluation for the next 12 months.
* Class II astronauts have some oral conditions that, if left untreated, are not 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.
Given annual exams, all astronauts are expected to retain a minimum Class II status, and only astronauts with Class I status prior to launch are considered for the International Space Station.
Clearance doesn't end there. In addition to annual exams, astronauts undergo pre-flight exams 18 to 21 months before launch. During this exam, the astronaut undergoes a thorough clinical and radiographic exam, including bitewing and panoramic X-rays. All necessary treatment is then to be completed 90 days prior to launch. The astronaut undergoes an additional exam to rule out any hidden pathology or any unreported recent oral injuries 30 to 90 days before launch. The astronaut is also expected to follow a meticulous oral hygiene routine during flight.
Think NASA recognizes how critical dental health is to the crew's function? Wait until you get aboard. Just in case something has slipped by all of those screenings, or in the event of an accident, every mission has two crew medical officers (CMOs) who are trained to perform not only medical emergency procedures, but dental emergency procedures as well. They are authorized to treat with antibiotics and analgesics, administer anesthetics, place temporary dental fillings, replace a crown with temporary cement, treat exposed pulp, and as a last resort, extract teeth. Any emergency treatment would include communication with ground support flight physicians, as the CMOs are not necessarily physicians or dentists themselves. However, since the ISS is in low earth orbit, a true emergency situation would likely result in a return to earth for proper treatment.
While in space, astronauts develop their own technique to maintain their hard-won oral health. With their water recycled and strictly limited, most brush and then swallow their toothpaste with a bit of water. Others spit their toothpaste into a towel. All of them know better than to skip their oral hygiene routine.
And if you'd like to sport NASA-worthy teeth and gums, you will too.