Why do astronauts get cavities? Student researchers drill into the data

Rachel Stubits
Thursday, November 28, 2019 - 4:01pm
Blake Eligh

Curiosity and a passion for research is taking four U of T students to the final frontiers of health and space. A paper by the student research team, presented at a recent international conference of space experts, is the first step in a process that could inform future research into the dental woes of space travellers 

Rachel Stubits, a third-year molecular biology student at U of T Mississauga, is lead author on the project, which seeks to understand why astronauts suffer more dental problems than their earthbound peers. In 2018, Stubits was looking for a side project to develop her research skills when she hit upon a fact that piqued her curiosity. 

“Dental caries—also known as tooth decay or cavities—are the single-most non-communicable disease in the world,” she says. “More than 97 per cent of people on Earth will experience it at some point in their lifetimes.” While prevention and treatment protocols on Earth are well-documented, Stubits wanted to know more about those who didn’t have ready access to treatment. “I wondered about people who are really far removed from our healthcare system. You can’t get much farther away than space.”

Tooth decay occurs when sugar-loving bacteria produce acidic by-products that can erode tooth enamel and, if untreated, lead to painful infections. The issue is particularly problematic for astronauts, with some studies suggesting that prolonged exposure to microgravity may increase the prevalence of dental caries. 

Currently, space agencies manage dental health with pre-flight assessment and prevention measures and post-flight treatments, but dental abscesses are the main medical reason behind medical evacuation from spacecraft because it’s difficult to treat in space.

The statistics behind current research warrant further investigation. “There are so many differences between humans on Earth and humans in space that could be contributing to the incidence rate of dental caries” she says, noting that variables such as air quality, diet, hygiene, or even gravity itself may contribute to the development of dental caries. “It’s difficult to pinpoint because of the small sample size and the number of variables.”

In October 2018, Stubits joined U of T’s Aerospace Team to develop a protocol for a review of literature about the issue. Her co-authors include fellow UTM molecular biology student Anisha Hundal, third-year U of T chemical engineering undergraduate student Claire Velikonja, and alumna Wendy Yao (H. B.Sc.., 2018)whose expertise includes global health and immunology. Their project lays the groundwork for a more detailed literature review that could inform future research into dental health in space. 

The team completed the protocol project in the summer of 2019 and, with funding from the Canadian Space Agency, Yao travelled to Washington, D.C. to present their work at the 70thInternational Astronautical Congress. That event draws an international and multidisciplinary group of agencies, companies, associations and institutes to advance knowledge and foster global cooperation in the development of space assets. “It’s so exciting to have the Canadian Space Agency take a chance on students,” Stubits says.

The group’s work is an important first step in the process of solving the problem of cavities in space. “Dental caries will become a bigger problem as the duration of space missions become longer and people are travelling in space for months or even years,” Stubits says. “We hope to solidify our understanding of the incidence rate, what is potentially causing it, and the possibility of microgravity being the culprit.” 

In early 2020, the team will begin work on a scoping review to discover potential patterns within the existing research. “There may be a difference in the ability of Streptococcusbacteria to succeed in causing dental caries in space without gravity,” Stubits says. “We would love to see this review help researchers in this field, especially those who study simulated microgravity on Earth, to decide what to focus their efforts on.” 

“I think working on a literature review is one of the most successful research formats for undergraduate students with a bit of extra time on their hands,” says Stubits. “This is all about collaboration, and it’s something that I love about research.”

Canadian astronaut and Commander Chris Hadfield answers questions about how astronauts brush their teeth in space: