F.R. von der Fehr

The Prevalence of Dental Caries in Europe 1990-1995

Caries prevalence data from recent studies in all European countries showed a general trend towards a further decline for children and adolescents. However, in several countries with already low carie

Fingernail Fluoride: A Method for Monitoring Fluoride Exposure

This work was based on the hypothesis that fingernail clippings can be used as a biomarker for the subchronic exposure to fluoride. The results provide data on factors that may affect the concentration of fluoride in fingernail clippings as determined with the electrode following HMDS–facilitated diffusion. The following variables had only minor or no effects on the concentrations: (1) the surface area of the clippings (intact, minced or filed into powder) that were placed into the diffusion dishes; (2) soaking in deionized water for up to 6 h; (3) soaking in fluoridated water (1.0 ppm) for 2 h, and (4) removal of the organic material of nails by dry ashing. Fingernail fluoride concentrations were approximately 50% higher than those in toenails. A 1–month period of increased fluoride intake by one of the authors resulted in significant increases in fingernail fluoride concentrations after a lag time of approximately 3.5 months. The fluoride concentrations in fingernail clippings obtained from three groups of Brazilian children were directly related to the concentrations in the drinking water (0.1, 1.6 or 2.3 ppm). The results indicate that: (1) HMDS–facilitated diffusion completely separates fluoride from intact nail clippings, so the need for ashing or other preparative methods is obviated; (2) fingernail fluoride is derived mainly from the systemic circulation, and (3) fluoride intake is reflected by the concentrations in fingernails.

The Influence of Fluoride Rinses on the Fluoride Content of Dental Plaque in Children

One sample of soft deposit was taken from each of 143 11 to 13-year-old children performing weekly mouth rinses with 10 ml 0.2% NaF or 0.2% NaCl. F was determined, and the ppm F calculated on the dry

Effect of fluoride on the saturation of an acetate buffer with respect to hydroxyapatite

Synthetic hydroxyapatite and powdered enamel were equilibrated with a pH 5.0 buffer for one or two weeks at 20 °C. When the liquid approached saturation with respect to hydroxyapatite, the fluoride ion activity was adjusted to 0.1, 0.5 or 1.0 parts/106 which made the liquid highly supersaturated with respect to fluorapatite. A rapid formation of a fluorapatite occurred, which made the liquid unsaturated with respect to hydroxyapatite. After further equilibration, the liquid once more approached saturation with respect to hydroxyapatite.

A study of carious lesions produced in vivo in unabraded, abraded, exposed, and F-treated human enamel surfaces, with emphasis on the X-ray dense outer layer

Abstract Caries was produced in sixty-seven premolars from children by means of the gold plate technique. Natural caries and lesions produced in pretreated enamel surfaces were studied by means of microradiography, macroscopic inspection, polarized light, and 32 P uptake. Except for the thickness of the surface layer, the produced lesions were found to be similar to natural caries. In unabraded enamel the X-ray dense surface layer was found to have an average thickness of 20μ, which is less than that observed in natural lesions. Enamel surfaces which were either abraded or abraded and exposed to the oral milieu for periods of 7–56 days, did not show significantly different lesions. The average thickness of the X-ray dense layer in these groups was 7–8μ. Topical treatment with a hexafluorostannate solution resulted in increased thickness of the surface layer. The results support the concept of a caries resistant surface layer, but indicate that this layer may be re-established after removal. Furthermore, the thickness of the X-ray dense outer layer in carious lesions appears to be influenced by the nature of the attack.

THE SOLUBILITY RATE OF UNABRADED, ABRADED, AND EXPOSED HUMAN ENAMEL SURFACES STUDIED BY MEANS OF ACTIVATION ANALYSIS

Abstract The solubility rate was expressed by the amount of phosphorus extracted in 5 min by 2-mm paper discs, moistened with 2 μl ammonium acetate-acetic acid buffer. In unabraded enamel surfaces of extracted teeth an average of 260 ± 15 ng phosphorus was found, and in abraded facets 486 ± 13 ng. In abraded facets exposed to the oral environment for periods of 1–49 days, the amount of phosphorus extracted by the first test ranged from 223 to 460 ng, depending somewhat on the length of the exposure time. In unabraded and exposed surfaces there was no significant difference between the first and the second test, whereas in abraded facets significantly lower values were found in the second test, viz. 418 ± 11 ng.

A Modified Enamel Biopsy Method for Fluoride Studies

The purpose of this study was to improve the sensitivity of the biopsy method developed by Brudevold et al. Enamel surfaces were abraded by means of rubber cups and silicon carbide. The slurry was collected by the lip of the cup, which was cut off and transferred to a plastic test tube. The material was dissolved in perchloric acid and buffered by sodium citrate. Fluoride was determined by a combination fluoride activity electrode and calcium by atomic absorption spectrophotometry. The method permits determination of the fluoride content in approximately 0.2-μm thick layers within single tooth surfaces. In two selected groups of 207 children (7–16 years of age) residing in high and low fluoride areas, the fluoride concentration in the enamel surface ranged from 1,000 to 6,000 ppm. In 33 children two successive layers were sampled, each being approximately 0.5 μm thick. In the first layer the fluoride concentration ranged from 2,000 to 5,800 ppm and in the second from 1,500 to 4,800 ppm.

Wear of teeth due to occupational exposure to airborne olivine dust

Objectives. To clarify whether high tooth wear of employees in a mining industry that extracts the mineral olivine could be associated with airborne dust exposure in their working environment. Method. The cumulative exposure to airborne mineral dust for the workers in the company was calculated on the basis of their period of employment multiplied by the airborne olivine-dust concentrations, which have been monitored continuously during the past 20 years for all divisions of the company. After invitation, 85% of the employees (n=191) were examined clinically and their dentitions were photographed and duplicated in plaster casts. Four clinicians, working independently, examined the sets of casts/photographs for tooth wear and ranked these from most to least. Two groups of employees were compared with regard to tooth wear, i.e. the 30% with the highest (case) and the lowest (control) estimated dust exposure levels. Tooth wear in the case and control groups was compared using a non-parametric test based on rankings (Mann-Whitney test). Results. Tooth wear differed significantly between the workers in the low and the high mineral dust exposure groups (p<0.001). The differences were also apparent within three age subsets, although statistical significance was reached only in the 34–44 years subset (p=0.002). Considerable individual variation was noted within the three exposure groups. Conclusion. Workers with high exposure to airborne olivine dust may contract considerable tooth wear.

A method employing activation analysis for the study of human enamel surface solubility rates in vivo and in vitro.

Abstract The method is based upon the dissolution of surface enamel in selected areas and the determination of phosphorus by means of neutron activation analysis. Filter paper discs, 2 mm in diameter, were applied to the cleaned tooth surface and moistened with 2 μl 1 M ammonium acetate-acetic acid buffer, pH 4.0. The amount of phosphorus extracted in 5 min was taken as a measure of the enamel solubility rate. Fifteen extracted premolars from young individuals were tested. Significant solubility rate differences were observed between unabraded and abraded enamel surfaces, the average phosphorus values being 260 ng and 486 ng respectively. Tests made in clinically intact areas of ten premolars in situ gave a mean of 101 ng phosphorus, but these teeth were not directly comparable to those above. The precision of the method ranged from 8 to 22 per cent. The technique is simple and the test is suitable for both clinical and laboratory studies.

The 32p uptake and the hardness of unabraded, abraded and exposed human enamel surfaces

Abstract Abraded facets were made in enamel surfaces of teeth in situ and exposed to the oral environment for periods of 1–82 days. After extraction, the in vitro uptake of 32 P was measured in selected enamel areas representing unabraded, abraded, and exposed surfaces. This part of the material comprised fifty-two premolars from children, and in eighteen of them the micro indentation hardness was also determined. Furthermore, the hardness was measured in unabraded and abraded surfaces of eight teeth from old individuals. The results showed that in the young teeth, the unabraded surfaces took up less 32 P and were softer than the abraded facets. Oral exposure of such facets resulted in impeded 32 P uptake and increased hardness. The old teeth were generally harder than the young teeth, but the unabraded surfaces of the old teeth were not significantly harder than the abraded facets.