Relative Frequency of Loss of Individual Molars of Rats during a Longevity Study

¹ Department of Animal Science, University of Florida, Gainesville, Florida

In a longevity study with 96 rats subdivided equally into dietary groups and fed four different levels of corn-soybean meal protein diets (11, 14, 17, and 20 per cent protein), with and without chlortetracycline (22 p.p.m.), observations made when the rats succumbed showed that (a) 17 per cent of the maxillary, compared with 11 per cent of the mandibular, molars were missing (P < 0.01); (b) in the mandible 6, 10, and 17 per cent of the molars in the first, second, and third positions were lost, respectively, while in the maxilla 29, 10, and 11 per cent losses had occurred in these three corresponding positions (P < 0.01); (c) 15 per cent of the molars were lost in the left compared with 13 per cent in the right quadrants; and (d) dietary protein level and chlortetracycline had no significant effect on the number of molars lost.