The Incidence of Dental Needs During Isolated Missions Compared to Non-isolated Missions: A Systematic Review and Implications for Future Prevention Strategies.

INTRODUCTION: Dental emergencies in isolated groups have always been difficult to treat. Especially in people or groups who cannot be evacuated and who need urgent dental assistance: long-term submarine missions, long-term spaceship trips, military or non-governmental organizations deployments in conflict areas, military maneuvers, etc. The dental and evacuation problems could put the success of the mission at risk, with relevant associated economic and strategic costs. Our study summarizes current evidence about dental problems in isolated personnel (submarines and Antarctic missions) compared to other non-isolation conditions (military deployment in conflict area, military maneuvers) with the objective to assess the need for specific dental equipment in special long-term isolation conditions. MATERIALS AND METHODS: We searched Medline, Cochrane Library, and Dentalgate between 1960 and 2017 for studies reporting dental disease in long-term isolation conditions (minimum 1 month) versus non-isolation conditions. We conducted the systematic review with all studies fitting the inclusion criteria. The comparison of the incidence rate was performed fitting a Poisson regression model to see the effect of the individual's condition on the incidence of dental event. RESULTS: Thirty-eight studies were included in the systematic review. Antarctic missions showed a higher dental incidence rate compared to non-isolation conditions, but submarine missions showed the lowest dental incidence rate. In the sub-analysis of acute dental events, those with great impact on unit effectiveness, the incidence rates were higher. Caries and secondary decay events were the most prevalent dental problem in all conditions, followed by periodontal pathology and fractures of teeth or tooth problems not due to tooth decay in isolation conditions, and then by molar problems and endodontic problems in non-isolation conditions. The most common acute dental events were third molar problems and endodontic problems in all conditions. CONCLUSION: This systematic review shows that the incidence of dental pathology in long-term isolation conditions may seem relatively infrequent but it exists and is relevant. Dental events are unpredictable, unrelated to trauma, and caused mainly by poor dental status. Preventive measures considerably reduce dental prevalence.

Beyond the Required LISA Free-Fall Performance: New LISA Pathfinder Results down to 20 µHz.

In the months since the publication of the first results, the noise performance of LISA Pathfinder has improved because of reduced Brownian noise due to the continued decrease in pressure around the test masses, from a better correction of noninertial effects, and from a better calibration of the electrostatic force actuation. In addition, the availability of numerous long noise measurement runs, during which no perturbation is purposely applied to the test masses, has allowed the measurement of noise with good statistics down to 20 µHz. The Letter presents the measured differential acceleration noise figure, which is at (1.74±0.05) fm s^{-2}/sqrt[Hz] above 2 mHz and (6±1)×10 fm s^{-2}/sqrt[Hz] at 20 µHz, and discusses the physical sources for the measured noise. This performance provides an experimental benchmark demonstrating the ability to realize the low-frequency science potential of the LISA mission, recently selected by the European Space Agency.

Charge-Induced Force Noise on Free-Falling Test Masses: Results from LISA Pathfinder.

We report on electrostatic measurements made on board the European Space Agency mission LISA Pathfinder. Detailed measurements of the charge-induced electrostatic forces exerted on free-falling test masses (TMs) inside the capacitive gravitational reference sensor are the first made in a relevant environment for a space-based gravitational wave detector. Employing a combination of charge control and electric-field compensation, we show that the level of charge-induced acceleration noise on a single TM can be maintained at a level close to 1.0 fm s^{-2} Hz^{-1/2} across the 0.1-100 mHz frequency band that is crucial to an observatory such as the Laser Interferometer Space Antenna (LISA). Using dedicated measurements that detect these effects in the differential acceleration between the two test masses, we resolve the stochastic nature of the TM charge buildup due to interplanetary cosmic rays and the TM charge-to-force coupling through stray electric fields in the sensor. All our measurements are in good agreement with predictions based on a relatively simple electrostatic model of the LISA Pathfinder instrument.