Caries Patterns of Intact and Sialoadenectomized Albino Rats of the Emory Wistar Strain Fed a Cariogenic Diet

¹ Emory University School of Dentistry, Atlanta, Georgia

In agreement with the report of Muhler and Bixler,¹¹ we found that sialoadenectomized rats fed a high-sucrose diet developed much more caries in the mandibular teeth than in the maxillary teeth.

The locations of the most severe and least severe lesions as to fissure and tooth found in our study are in agreement with the report of Dalderup.¹It may be of interest that we, as well as Dalderup, rarely find lesions in the third molars. This very low degree of susceptibility of the third molars differs from that seen by Volker¹² in hamsters. Volker found the most severe decay in the third molars.

Our procedure has been to start feeding our animals the cariogenic diets at 21-25 days of age, and, since the Emory Wistar strain, when sialoadenectomized, develops severe caries in the first and second molars in 70 days, we ordinarily terminate the experiment at this time. One possible explanation of the relatively low incidence and extent of the caries found in the third molars of our strain may be due to the fact that the third molars erupted 10-14 days after the experiments had been started and were therefore exposed to the cariogenic diet a shorter time than the first and second molars. Perhaps this shorter exposure time is not sufficiently long to permit any appreciable development of lesions in these teeth.

In our several experiments feeding the Harvard 100 diet, we have never observed any sex difference in our animals in the susceptibility to caries. To check this observation, 100 males and 100 females that had been sialoadenectomized and fed this diet for 70 days were selected in equal numbers from various experiments. The average caries scores of the animals were 46 for the males and 44 for the females. It is of interest that in 9 experiments conducted over a period of 10 years, various groups of animals ranging from 20 to 25 in number exhibited average caries scores of from 39 to 46, with an over-all average of 43. These data indicate that the Emory Wistar strain of albino rats gives reproducible results in studies on dental caries.

Twenty littermate pairs of Emory Wistar strain albino rats were selected at weaning, ten pairs of males and ten pairs of females. One of each pair was subjected to a sham operation, and the other was sialoadenectomized. All animals were fed a highly cariogenic high-sucrose diet for a 70-day period, at the end of which time the animals were sacrificed and the teeth scored for caries.

Removal of the major salivary glands of the rats of the Emory Wistar strain resulted in an increase in incidence and extent in caries of between 300 and 400 per cent. There was a high degree of bilateral symmetry in incidence and extent of caries in both groups. Observations of the caries in a large group of animals in this strain showed no sex difference in susceptibility to caries. The Emory Wistar strain of albino rats gives reproducible results in caries studies.