Oral health in space: Understanding impacts of microgravity and developing countermeasures for space applications

Space oral medicine is an emerging interdisciplinary field dedicates to preserving oral health during space missions, managing dental conditions throughout extended spaceflights, and utilizing the unique microgravity environment for scientific innovation and advancement. It also plays a crucial role in astronaut selection, training, and spacecraft design. Research into microgravity's effects on oral health has been pivotal in advancing this field. As long-duration missions became more feasible, understanding the oral health challenges under microgravity conditions grows increasingly important. Microgravity can lead to bone loss, muscle atrophy, changes in oral microbiota, virus activation, and impacts on stem cell differentiation, all of which are interconnected and share common mechanisms. These changes can affect not only oral health but also overall well-being. The mechanisms underlying these effects are complex and multifaceted. For instance, microgravity-induced mechanical unloading can disrupt bone remodeling by inhibiting osteogenesis and promoting osteoclast activity. This can result in reduced bone density and increased fracture risk. Similarly, muscle atrophy can impact the muscles of mastication, potentially leading to difficulties in chewing and swallowing. Changes in oral microbiota can increase the risk of dental caries, periodontal diseases, and other infections, while virus activation may contribute to oral lesions and other complications. Nevertheless, the microgravity environment manifests dualistic biological effects. It brings new ideas to cell culture, directed induction, and tissue regeneration by affecting stem cell proliferation and differentiation. To safeguard astronaut health, the implementation of comprehensive countermeasures is crucial where these include resistance training, pharmacological treatments, nutritional supplements, vaccinations, and probiotic therapies. These approaches not only address the immediate challenges of spaceflight but also pave the way for sustainable human exploration beyond Earth. By advancing targeted oral health protocols, we can improve astronaut well-being, enhance operational success, and contribute to the viability of future long-term missions.