M.E.J. Curzon

Combined Effect of Trace Elements and Fluorine on Caries

Caries examinations of 251 children aged 12 to 14, from two Ohio towns that use water supplies with high contents of boron and strontium showed a mean DMFS score of 3.56 compared to a score of 5.54 in a control group of 338 children. Findings suggest that the significantly lower caries prevalence in the former group is related to the boron and strontium content of the water rather than a 0.2 ppm difference in the fluorine level.

The Relation Between Caries Prevalence and Strontium Concentrations in Drinking Water, Plaque, and Surface Enamel

Samples of plaque and surface enamel were collected from 80 boys aged 14 years living in five communities in Ohio (USA). Mean (± SE) strontium concentrations in plaque were 1.43 ± 0.18 μg/g (wet) and 12.34 ± 1.63 μg/g (dry). For surface enamel, the mean concentration was 421 ± 31 μg Srlg. Concentrations of strontium in both plaque and enamel were significantly related to strontium levels in the drinking water. Caries prevalence as DMFS was inversely related to strontium levels in water, plaque, and enamel.

Environmental Effects of Molybdenum on Caries

Examination of 786 children in California towns situated on soils with high and low molybdenum contents failed to show differences in caries prevalence.

Interactions of Zinc with Fluoride on Growth, Glycolysis and Survival of Streptococcus mutans GS-5

Effects of zinc and/or fluoride on growth, glycolysis and survival of Streptococcus mutans GS-5 were examined in vitro. Zinc inhibited growth and glycolysis, and enhanced the antimetabolic activity of fluoride. Zinc alone had little effect on cell survival. During cell growth without pH control a protection from cell death was mediated by fluoride, which appeared to be caused by a higher final pH in the culture medium. When cell death was observed under controlled pH conditions in a lactate-acetate buffer at pH 6.5, 5.0 or 4.0, fluoride was bactericidal only at pH 4.0. However, the combination of zinc plus fluoride was strongly bactericidal at all pH values that were tested.

Urinary Excretion of Fluoride Following Ingestion of MFP Toothpastes by Infants Aged Two to Six Years

The absorption and excretion of fluoride in a group of 25 infants (<6 years of age) were followed for up to seven hours after the ingestion of a known quantity of either sodium monofluorophosphate alone in solution, or toothpastes with sodium monofluorophosphate and an abrasive of either hydrated silica or dicalcium phosphate dihydrate. Fluoride appeared to be well-absorbed based on the excretion patterns found. From the results, it was concluded that parents of pre-school-aged children should now be given appropriate advice regarding their childrens use of fluoride toothpaste. Such use of fluoride toothpaste should be closely supervised by the parents, and only a smear of paste, about the size of a pea, should be used, particularly where fluoride supplements are used. Because of the likelihood of toothpastes with even higher amounts of fluoride being marketed, it would also appear that toothpaste manufacturers and researchers in caries prevention should look further at the problem of fluoride absorption from toothpastes in infants.

Combined Effect of Trace Elements and Fluoride on Caries: Changes Over Ten Years in Northwest Ohio (U.S.A.)

Dental caries examinations were carried out in an area of low caries prevalence, ascribed to a combined effect of fluoride and other trace elements. Repeat examinations in 1978 on lifelong resident children aged from 12 to 14 yr showed caries distribution patterns to be essentially the same as those found in a previous study in 1968. Some changes in DMFS scores had occurred, which were associated with changes in the strontium content of the drinking water; low caries levels were significantly associated with high strontium concentrations.

Effects of Fluoride, Lithium, and Strontium on Growth and Acid Production of Mutans Streptococci and Actinomyces viscosus

Eight strains of mutants streptococci and two strains of Actinomyces viscosus were studied to determine (1) their relative sensitivities to fluoride, lithium, and strontium and (2) whether lithium or strontium interact to enhance the known antimicrobial effects of fluoride. Analyses of variance of the data revealed a major inhibition of growth and acid production by fluoride, but not by lithium or strontium. Fluoride (5 mg/l) inhibited cell growth of all strains tested by a mean of 17% and total titratable acid production by a mean of 31%. However, there were marked differences between the strains. Mean total titratable acid was inhibited by fluoride least with the A. viscosus strains (15%) and most with the mutans streptococci (34%). Although interactions among the elements were statistically significant, they were generally slight in magnitude.

Relationship of Strontium in Drinking Water and Surface Enamel

The Sr content of surface enamel of 233 teeth from nine communities was related to drinking water Sr concentrations. These water concentrations ranged from 0.02 μg/ml to 33.9 μg/ml. The relationship between enamel concentrations and water concentrations was linear for water concentrations less than 10μg/ml Sr, but leveled off at approximately 300 μg/gm Sr in the enamel for communities with greater than 10 μg/ml Sr in drinking water. Binding of Sr to components in the oral environment is proposed as an explanation of this effect.

Effects of Fluoride, Lithium, and Strontium on Intracellular Polysaccharide Accumulation in S. mutans and A. viscosus

Fluoride (5 mg/l) consistently depressed the accumulation of intracellular iodophilic polysaccharides (IPS) in Streptococcus mutans strains BHT, FA-1, and GS-5 by over 90% and in Actinomyces viscosus strain RC-45 by over 50%. There was little further reduction in IPS content when fluoride was increased from 5 to 100 mg/l. Lithium (0 to 1 mg/l) neither enhanced nor inhibited IPS accumulation, nor did it modify the inhibitory effects of fluoride in three of the four strains tested. Strontium (0 to 100 mg/l) did not alter IPS accumulation in S. mutans GS-5 but decreased accumulation (<10%) in S. mutans FA-1 and BHT and significantly enhanced IPS accumulation in A. viscosus RC-45. Analysis of variance indicated no statistically significant interactions between fluoride and strontium, fluoride and lithium, or strontium and lithium.

Clinical Science Physical and Chemical Effects of Toothpastes on Dental Enamel

The effects on surface enamel of an experimental toothpaste containing Sr-EDTA, sodium ricinoleate, and fluoride were compared with those of a commercially available fluoride toothpaste. Knoop indentations, before and after treatment with control and experimental toothpastes, showed no significant changes. Both toothpastes rendered the enamel surface less soluble after treatment.