Abraham E. Nizel

Effect of Food Ash, Phosphate, and Trace Minerals Upon Hamster Caries

EPIDEMIOLOGICAL surveys have indicated that the consistent geographic variation of caries prevalence in human beings may be related to an environmental factor. Although the evidence is quite conclusive that there is an inverse relationship between the level of fluoride in water supplies and the incidence of dental decay, it has been suggested that investigations be conducted to determine whether a relationship also exists between the composition of foods produced in different soil areas and the incidence of dental decay in these areas.2 Recently, Hewart and Eastcott3 have shown that this type of relation may exist. Experiments conducted at our laboratories have shown that corn and milk produced in two widely separate soil areas (New England and Texas) have different effects on the development of caries when included in the diet of the Syrian hamster.4 Spectrographic analysis revealed that the ashes of corn and of milk produced in these two areas were quantitatively different. For example, an ash of the Maine corn had 2 to 2.5 times more manganese, magnesium, and copper, 3 times more aluminum, 4 times more iron, the same amount of molybdenum, and one third as much nickel as the Texas corn. The results of an experiment in which four combinations of Texas and New England corn and milk were fed in the diets of hamsters indicated that a caries-producing factor present in both the corn and milk from New England was mainly responsible for the differences noted.5 In order to determine whether this cariogenic factor was a mineral substance, two diets were ashed at 5500 C., and the ash was added to equivalent amounts of each diet, thus doubling the mineral content. These ash-supplemented diets were fed to hamsters in comparison with unsupplemented diets. It was found that, although no regional differences in the cariogenicity of these foodstuffs was evident, the ash of both the Texas and New England diets caused a 60 to 70 per cent reduction in dental caries.6 7 It is likely that this effect was due to the larger amounts of minerals in the ash-supplemented diets.

Cariostatic Effects of Three Types of Phosphates when Fed Singly or in Combinations in the Diets of Rats

More than 100 experiments have been conducted by over a score of investigators in order to evaluate the cariostatic effectiveness of 20 or more different phosphate compounds when fed in cariogenic diets to rodents.1 In most cases these authors observed significant reductions in dental caries, and in several instances dental caries was completely prevented. In essentially all these studies only one phosphate was fed to each group of animals. Mixtures of the same type of phosphate (i.e., Na2HPO4 and NaH2PO4, 1: 1) were fed in a few instances1 in an effort to obtain a neutral mixture that would not disturb acidity of the diet. Harris and Nizel2 recently reported the results of an experiment in which the phosphate anion (orthophosphate) was held constant while three cations were varied in the diets of rats. In comparison with the control group, the rats fed predominant amotunts of Ca-, K-, and Na-orthophosphates showed reductions in caries scores equivalent to 29 per cent; 71 per cent, and 81 per cent, respectively. When all three were added to the diet in equal amounts (on a P basis), the reduction in caries was 45 per cent. Thus the Naand K-orthophosphates were more cariostatic than the Ca salt, and the data indicated that the Ca-orthophosphate interfered with the cariostatic activities of the Na and K salts when the three were fed together. The above experiment was conducted because there has been some concern that foods and diets supplemented with single phosphates might contain excess amounts of Ca, Na, K, etc., that would provoke metabolic stress due to mineral imbalance. Even

The caries-producing effect of similar foods grown in different soil areas.

A STATISTICALLY significant higher incidence of dental caries has been produced in hamsters fed diets containing corn and dried whole milk produced in New England, in comparison to those fed simila...

Cariostatic action of fat-imbedded potassium phosphate when fed in the diet of rats.

Abstract Granular potassium dihydrogen phosphate was imbedded by mixing into hydrogenated lard, cooling and pulverizing. It was added to a cariogenic diet in amounts sufficient to double the phosphorus content of the diet to 0.8 per cent. Other batches of this diet were supplemented either with the lard alone, or with lard and the granular KH2PO4 mixed into the diet separately. In two successive experiments these three diets and the control unsupplemented diet were fed to groups of twenty-four rats each beginning when they were 8 days old. They were then sacrificed, and the dental caries of the molars were scored. No significant differences between groups were noted with respect to diet consumption, body weight gain, femur length or the phosphorus content of blood serum and saliva. The four diet groups (control diet, control diet + 5.2 per cent hydrogenated lard, control diet + 5.2 per cent hydrogenated lard + 1.73 per cent KH2PO4, and control diet + 1.73 per cent KH2PO4 imbedded in 5.2 per cent hydrogenated lard) showed average caries scores, respectively, as follows: Series I, 18.9, 22.9, 9.3 and 4.6; Series II, 24.8, 43.7, 17.8 and 9.8. Thus, the addition of fully hydrogenated lard (m.p. 61–65 °C) to the diet caused a significant increase in caries. Although the lard-imbedded phosphate was essentially insoluble in water, it was significantly more cariostatic than the unimbedded phosphate. The implications of these results in relation to the mechanism of the phospate action are discussed. It is suggested that imbedded water-soluble phosphates and unimbedded water-insoluble phosphates may be more cariostatic because they are absorbed more slowly and continuously, and this results in increased retention.

Quantitative Technique for Pulverizing Rodent Teeth

Recently ixe described a technique for t of intact molars by immersing the cleai rats in a buffered ficin solution (NVx :HARRiS, IR. S., NIZEL, A. E., anti M J. dent. Res., 42:1251, 1963). This enzyme loosens the teeth from their socd each tooth can be lifted out by force fracturing it. We present here a simple heely pulverizing rodent teeth preliminary cal analysis or the separation of dentin; by procedures such as the modified I acetone flotation method of Gilda (J. 30:445---52 1951). It is common practice in dental pulverize rodent teeth by hand grind diamond mortar and pestle. Gilda has re he recovered between 86 and 90 per weight of 48 pooled rodent molars al fineness. Dirkson. and Hester (J. dent. R

Effect of particle size on the cariostatic action of potassium acid phosphate.

Abstract Four batches of potassium acid phosphate crystals of different particle sizes (10–20,20–30,30–40,40–50 mesh) were added at a 1.7% level to a caries-producing diet, thus doubling its phosphorus content. The unsupplemented diet (A) and the four supplemented diets (B, C, D, E, respectively) were fed to groups of twenty-four rats for 98 days, beginning at 8 days of age. The molar teeth were then scored for dental caries development. The average caries scores of groups A to E were 38.8, 36.4, 7.7, 13.5 and 11.8, respectively. Thus, the score of the group (B) fed the coarse 10–20 mesh phosphate supplement was essentially the same as that of the control group. The greatest reduction in caries development (80 per cent) was observed in the group (C) fed the 20–30 mesh phosphate. The two groups (D, E) fed finer granulations of phosphate showed 65 and 70 per cent reductions, respectively. These results indicate that the cariostatic action of potassium acid phosphate is predominantly on the tooth surface, and that the particle size of a dietary supplement of phosphate can significantly influence its cariostatic action.

Metabolic Significance of the Ratio of Calcium to Phosphorus in Foods and Diets

Introduction If future research should reveal that dental decay in human beings can be controlled b) the addition of phosphates to foods, we must be certain that the kinds and amounts of phosphate that are added will provoke no adverse effects in people who consume these foods. It is to be expected that questions will be raised concerning the safety of foods supplemented with phosphates, since there are a number of reports in the literature which indicate that under certain conditions the feeding of large amounts of phosphates to animals may interfere with the absorption of minerals and may also stimulate the formation of renal stones. It should be emphasized that the conditions under which