This study presents data on the mineralization of the teeth in rats subjected
to prolonged space flight. Although the pitfalls inherent in quantitative radiologic
studies were kept in mind, there was an advantage in knowing the resorption
in the spongy bone and the ambiguous result on dense bone in the same animals.
Special efforts were made to standardize the regions of tooth structure measured,
in the hope that masses of tissue in low experimental reactivity might not obscure
more highly reactive sites.
Heads were divided sagittally and x-rayed. Optical densities were measured
on the films with a densitometer calibrated in American Standard Diffuse Density
units. Limitations were principally: 1) that readings would be taken at some
reasonable distance from the apex (region of tooth formation) to reach the mineralized
band of structure and 2) that readings would not be over the tip of the tooth
since the greatest part of the tooth was in fact closed in thin bone. While
the density readings followed a logarithmic scale, the light transmission values
were on an arithmetic percentage scale.
Although enamel values in the flight animals, both at recovery and 25 days post-
flight, seemed lower than controls, the difference was not significant. Other
findings suggest a small amount of mineral loss may have occurred during the
experimental period. Mineral repletion was not observed during the recovery
period. The thin bone of the mandibular body was slightly reduced in both syn-
chronous and flight rats, but rose to the level of vivarium controls after the
recovery period. Changes of similar direction were found in the heavy bone underlying
the molar teeth, suggesting that the stimulus of chewing was reduced in these
groups, with restoration of a firmer diet during the recovery period increasing
masticatory activity and improving bone structure.
Reference C782-5 Title of Study Savostin-Asling, I. et al.: Mineralization
in Teeth and Jaws, as Judged Radiographically, in Rats of the Cosmos 782 Experiment:
Final Reports of U.S. Experiments Flown on the Soviet Satellite Cosmos 782.
S.N. Rosenzweig and K.A. Souza, eds., NASA TM-78525, 1978, pp. 308-320.
¥ = publication of related ground-based study