Rune Söremark

FLEXURE STRENGTH OF RESIN-MODIFIED GLASS IONOMER CEMENTS AND THEIR BOND STRENGTH TO DENTAL COMPOSITES

The flexure strength of three resin-modified glass ionomer cements and one conventional glass ionomer cement and their bond strength to dental composites were studied by measuring the three-point bending and the shear strengths. The bond strengths between the dental composite and the resin-modified glass ionomer cements were dependent on the curing modes. Resin-modified glass ionomer cements bonded significantly more strongly to cured dental composites than dental composites bonded to cured resin-modified glass ionomer cements. However, the dental composites showed a significantly stronger bonding to the resin-modified glass ionomer cements than to the cured conventional glass ionomer cement, to which the dental composite did not adhere without acid etching. The flexure strengths of the resin-modified glass ionomer cements were significantly improved compared with the conventional one but were still significantly lower than that of the dental composites.

A comparison of the distribution of some halide ions in the body

Abstract The distribution of the halide ions F − , Br − , I − and tentatively Cl − , and the pseudo-halide ion SCN − has been studied in mice and rats. Whole body autoradiography, microautoradiography, double tracer autoradiography, and scintillation counting methods have been used. Similarities and dissimilarities in the distribution pattern of the various ions are described and discussed. Although the chemical and physical properties are similar for the elements studied—with some notable exceptions for fluorine—their distribution patterns in the body show pronounced dissimilarities.

Improved resolution in autoradiography with radioiodine using the extranuclear electron radiation from 125I.

In autoradiographic experiments with labelled micro test-charts, stain-cases, and histological sections, 125I has proved to offer significantly better resolution than 131I. Autoradiographic techniques favouring a registration of the low energetic internal conversion- and Auger-electrons emitted from 125I are discussed.

Analysis of Inorganic Constituents in Dental Calculus by Means of Neutron Activation and Gamma-Ray Spectrometry:

Approximately 80 per cent of dental calculus by weight has been found to be composed of such inorganic material as calcium, magnesium, phosphate, carbonate, and fluoride.1-5 There is, however, at this time no full agreement about the composition. Moreover, very few investigations have been published concerning the concentrations of various elements in calculus. This lack of quantitative data of the various constituents may be due to the fact that the chemical characteristics are variable but probably also that quite reliable analytical methods have not been available for the determination of a lot of trace elements present in biological materials. The purpose of the present investigation was to study the concentrations of some elements in dental calculus quantitatively and, for many other kinds of biological materials, to evaluate a new rapid method for analyzing inorganic components.

Distribution of bromide in mice. An autoradiographic study with Br82

Abstract (1) The distribution of Br 82 in entire mouse cadavers has been studied autoradiographically at various intervals after intravenous injection. (2) The concentration of Br 82 in the organs of fully developed foetuses has been compared with that in their dams. (3) Br 82 levels in various tissues have been determined quantitatively on autoradiograms and histological sections. Tissue levels are expressed as percentages of the blood level. (4) The results are compared with those obtained for other halogens. Special attention is given the stomach, central nervous system, salivary glands and thyroid glands. (5) Among other clinical and experimental applications of Br 82 measurement of the extracellular space and studies of gastric secretion are discussed.

Autoradiographic Localization of Bromide (Br82 and Br80m) in the Gastric Mucosa

Summary 1.The accumulation of bromide ions in the stomach was studied autoradiographically in mice and rats. 2.Br 82 and Br 80m were used. The internal conversion of the two γ-rays of Br 80m results in the emission of shell electrons, which were found excellent for autoradiography. 3.Bromide ions were found to be transported into the gastric juice through the gastric mucosa after intravenous injection of a trace dose of ammonium bromide. 4.The highest concentration of bromide within the gastric mucosa was found in the surface epithelium of the fundic part.

Abrasion of acrylic veneers by simulated toothbrushing

The abrasion responses were tested on four acrylic veneer materials, K + B Plus, K + B 75, Isosit, and Ivocron. The studies were performed in two independent research laboratories. Two different brushing machines were used with an abrasive slurry. The results were used for comparing the degree of abrasion for the resin materials. Three analytical methods of measuring the degree of abrasive wear were used: surface profile measurement, microscopic evaluation, and measurement of loss of volume. Isosit showed the best abrasion resistance of the four materials tested.

Influence of phytic acid on zinc phosphate cement.

The influence of phytic acid on the properties of zinc phosphate cement was studied by adding 2-13 wt% phytic acid to the liquid. Improved mechanical strength and stability were found for some cements prepared from commercial powders when liquids with increased phytic acid content were used. The results indicate that the formation of increased amounts of zinc phytate has a favorable effect on the properties of zinc phosphate cement.