Dental changes induced in rats by chronic exposure to adverse environments

¹ Department of Experimental Dentistry, School of Aviation Medicine, USAF, Randolph Air Force Base; and Clayton Foundation Biochemical Institute, The University of Texas, Austin, Texas

The histology and chemical composition of teeth were examined from rats acclimated for 18–24 weeks to cold (3°C), neutral (24°C) or heat (36°C), at barometric pressures of either 750 or 380 mm Hg. There were negligible histological changes in cold alone, but altitude induced changes in the mesenchymal elements of the teeth. These were made more severe by superimposed cold, but superimposed heat counteracted some of these effects. In the latter group, however, there were ectodermal changes. Chemical studies on these teeth revealed significantly reduced concentrations of calcium, phosphate and magnesium in the altitude- and heat-exposed rats. The cold-acclimated rats, as was the case histologically also, did not differ from the controls. Protein and iron content did not differ significantly among the groups. There were significant changes in the ratios of calcium, magnesium and phosphate. Possibly the basic inorganic composition of the teeth of altitude acclimated rats was changed since the Ca/PO₄ ratio was low. X-ray diffraction failed to confirm this, however.