Abstract
It has been noted by Hoppert et al 1 that white rats which received comparatively coarse foods were more prone to develop dental caries than those animals receiving a finely ground ration. This was explained on the basis of impaction; the coarse food particles became firmly lodged in or between the teeth and caries developed following the fermentation of these particles. The finely ground food was not subject to impactions; as a result dental caries did not develop in the absence of a fermentable material.
In this experiment an attempt was made to determine the ability of certain acid producing organisms in pure cultures to produce caries when introduced in connection with a sterilized coarse ration. The following cultures were employed:
No. 1. Lactobacillus acidophilus, oral strain, isolated from an old rat with extensive caries.
No. 2. A rough type of L. acidophilus, from the mouth of a human having dental lesions.
No. 3. A cocco-bacillus from same source as No. 2.
No. 4. A coccus of fowl origin, isolated in pure culture from a fowl having a partially eroded beak.
The diet chosen for the rats was one that was adequate for growth, retained its physical characteristics upon sterilization and was palatable. The formula for the ration in percentages by weight was as follows: Alfalfa 10, corn 63, oilmeal 15, yeast 5, casein 5, sodium chloride 1, and calcium carbonate 1.
The ration after having been thoroughly mixed, was placed in suitable containers, plugged with cotton and autoclaved for 30 minutes at 15 pounds pressure. A control container was plated for bacterial growth to insure sterility. After being sterilized the food was broken up with a sterile glass rod. One cc. quantities of 24-hour yeast extract broth 2 cultures of the organisms were added to the rations daily.
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