Dental Caried in the Rat, Mus Norvegicus I. The Incidence and Extent of Tooth Decay in Three Strains of Rats Fed Finely Powdered, Synthetic Rations

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Abstract
Three strains of Norway rats, two white and one black, totalling 401 rats, were employed in this study; they were raised by mothers on natural food rations, and no strain was bred for high caries-susceptibility. The synthetic and finely powdered rations used contained all the nutrients seemingly necessary for good growth and maintenance of health. Sucrose or glucose comprised 63 to 73% of the rations. The rations were fed for periods of 60 to 98 days. The presence of tooth decay was determined by alternately grinding and inspecting the molars for yellow, soft enamel or yellow, soft dentin at successive planes. Tooth decay developed in all three strains. One white strain, strain C, developed 60% more decayed areas, 160% more extensive areas of decay, and 400% more cavities than did the other white strain. The black strain fell midway between the two white strains in caries-susceptibility. A 60-day feeding period for strain C rats was found to be as satisfactory as a period of 77 or 98 days, and an even shorter period might be sufficient.