Is oral health affected in long period space missions only by microgravity? A systematic review

Abstract

BackgroundSince the starting of Space Age astronaut's health has been a subject of the utmost importance. To date, numerous studies describe the effect of microgravity on the body health of the astronauts. Some of these studies analyzed dental diseases and were conducted in conditions of microgravity and simulated microgravity, during short or long periods. Taking into account the increase of long space missions, it is necessary to systematically review the oral health events related with short and long periods spent in space missions with all the available evidence. MethodsTo identify all relevant oral diseases attributed to the effects of microgravity, we performed a rigorous systematic review regarding the published articles regarding microgravity and dental diseases from 1969 to 2018. Databases such as Pubmed, Cochrane, Scielo, Google Scholar and the NASA were consulted. Additional studies from the reference lists of the selected articles were included in order to get a greater complete overview. Ten scientific documents (containing 12 studies) with a direct relation with oral/dental health and microgravity were assessed. ResultsFive studies about short period missions (≤30 days) were included. The studies showed increases of cortisol as well as salivary immunoglobulin A (IgA) and salivary IgG. Seven studies about long period missions (>30–220 days) were included, and the more important fact retrieved was the increase of anaerobic bacteriae. ConclusionFuture long-term missions to Mars or to space stations will require 18–24 months of exposure to microgravity, that, added to other conditions, could have potentially deleterious effects on human physiology, including oral health. Preventive measures, adequate material and training of the crew have to be applied to avoid an oral health event to jeopardize the mission.