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International Journal of Dentistry
Volume 2011, Article ID 548068, 5 pages
Research Article

Evaluation by an Aeronautic Dentist on the Adverse Effects of a Six-Week Period of Microgravity on the Oral Cavity

1JBR Institute of Health Education Research & Technology, India
2Kepler Space University, Bluffton, SC 29909, USA
3Faculty of Earth & Life Sciences, Vrije Universiteit Amsterdam & ILEWG, Amesterdam, The Netherlands
4Catholic University, Leuven, Belgium

Received 2 July 2011; Revised 7 October 2011; Accepted 8 October 2011

Academic Editor: Francesco Carinci

Copyright © 2011 Balwant Rai et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


Objective. HDT bed rest condition is a simulated microgravity condition in which subject lies on bed inclined −6 degree feet up. To determine the influence of a simulated microgravity (HDT bed rest) on oral cavity, 10 healthy male volunteers were studied before, during, just after, and after 6 weeks of the simulated microgravity condition of −6° head-down-tilt (HDT) bed rest. Materials and Methods. Facial nerve function, facial sensation, chemosensory system, salivary biomarkers were measured. Results. Lactate dehydrogenase, MIP 1 alpha, malonaldehyde, 8-hydroxydeoxyguanosine, and thiocyanate were found to increase significantly, while flow rate, sodium, potassium, calcium, phosphate, protein, amylase activity, vitamin E and C, and mouth opening were decreased in simulation environments in contradiction to normal. The threshold for monosodium glutamate (MSG) and capsaicin increased during microgravity as compared to normal conditions. Moderate pain of teeth, facial oedema, mild pain, loss of sensation of pain and temperature, decreased tongue, and mandibular movement in simulation microgravity environments were observed. Conclusions. These results suggest that reversible effect of microgravity is oedema of face, change in taste, abnormal expression of face, teeth pain, and xerostomia. Further study will be required on large scale on long-term effects of microgravity on oral cavity to prevent the adverse effects.