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A series of experiments were carried out to determine the effect of the rate of gland function on parotid saliva fluoride levels in the human. Means for fluoride for stimulated parotid saliva ranged from 0.012 to 0.02 ppm. These are much lower levels than those previously reported for whole saliva and support other electrode analyses recently reported. In a 3-hour experiment involving continuous exogenous stimulation, salivary fluoride levels showed no alterations suggestive of depletion. Significantly higher levels of fluoride were found in parotid saliva collected without exogenous stimulation. It is suggested that the glandular mechanisms responsible for these observations are purely passive in nature with the fluoride ion probably moving in bulk flow with the fluid of secretion as it is generated by the secretory cells. However, the exact mechanisms which govern absolute saliva fluoride levels remain obscure.

Dental caries is a multifactorial disorder, the initiation and progression of which are affected by factors related to host susceptibility, oral microflora, and diet. Interlocking triple rings are frequently employed to demonstrate that microorganisms, fermentable carbohydrates, and a susceptible tooth surface are all requisite in the caries process. It is well established that lesions do not develop in gnotobiotic animals and that dietary modification such as carbohydrate restriction significantly restricts caries activity. There is a paucity of knowledge on the effect of specific environmental factors on caries incidence.In an earlier study (1 ) it was found that lighting significantly affected caries incidence in the golden hamster. These animals were fed a diet containing 61% sucrose over a 15-week period. Under these conditions carious breakdown was very extensive and in many cases the crowns were virtually destroyed. The authors pointed out that this overwhelming involvement may have caused a loss of masticatory ability resulting in reduced chewing, ingestion, and absorption of food.There was thus a need for the testing of the effects of light on caries incidence in a more sensitive model with a much less advanced state of destruction induced. Such a model has been developed for caries evaluation in which the cotton rat (Sigmodon hispidus) is weaned at 12 days of age and placed on a cariogenic diet (2). With a dietary sucrose level of approximately 6%,

While studying natural diets which were cariogenic to the cotton rat, Constant, Sievert, Phillips, and Elvehjem1 found that the degree of dental caries produced by an oatmeal diet was sharply decreased by the inclusion of finely ground oat hulls in the diet. The protective effect was greater at the 25 per cent level than at the 12.5 per cent level. Later work by Taketa and Phillips2 demonstrated that oat hulls were also protective in a semipurified diet at both 25 and 10 per cent levels. These workers furnished evidence suggesting that the protective effect was due neither to a brushing or abrasive action by the hulls nor to a dilution of the cariogenic diet by the hulls. They also verified an earlier observation by Constant et al.1 that the ash portion of the hulls was not anticariogenic. Jenkins and Phillips3 showed that the crude fiber, hemicellulose, and lignin fractions of the hulls were devoid of anticariogenic activity. Taketa and Phillips2 found that the greatest activity was located in an ethanol-soluble fraction of the hulls, which comprised less than 5 per cent of their weight. Some activity remained in the residue; however, later studies4 showed that extraction with ammoniacal ethanol removed activity that was not removed by ethanol alone.The activity in the ethanol extract not only was effective in the inhibition of dental caries but was also capable of inhibiting the growth of organisms isolated from the carious cotton rat tooth.5 This observation, coupled with the fact that a pure culture of Lactobacillus acidophilus var. Farr was inhibited by the extracted solids, indicated that the anticariogenic activity of oat hulls was related to an alteration in the oral flora of the cotton rat. Using L. acidophilus as an assay organism for oat-hull anticariogenic factors, Taketa and Phillips5 found the active factors to be acidic in nature and perhaps to be certain phenolic acids and palmitic acid.Madsen4 assayed other seed hulls for their anticariogenic activity by feeding them in an oatmeal diet at the 25 per cent level. It was found that, in addition to oat hulls, the hulls of rice and peanuts were also effective and reduced the incidence of caries by about 75 per cent; the hulls of cottonseed and barley reduced the incidence by about 35 per cent. Madsen also demonstrated that the acidic fraction prepared from ethanol extracts of these hulls was effective as a growth inhibitor of L. acidophilus var. Farr.Subsequent studies demonstrated that oat hulls were also anticariogenic in the diet of the albino rat. Madsen4 found them to be anticariogenic when fed in a semipurified diet to the Harvard strain of caries-susceptible rats. Buttner and Muhler6 demonstrated

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