Roy I. Holland

Effect of sodium fluoride on LS cells.

The fluoride sensitivity and the lethal concentration of LS cells were determined. The cells were adapted to grow in the presence of lethal concentrations of fluoride. The adaptation persisted after removal of fluoride. Any possible binding of the fluoride to medium components was excluded.

Cytotoxicity of fluoride

The present summary and the following papers (I-VIII) have been submitted in partial fulfilment of the requirements for the degree of Doctor Odontologiae at the University of Oslo.Effect of sodium fluoride on LS cells. (Coauthors: Jan K. Hongslo and Jon Jonsen) J. Dent. Res. 1974, 53, 410-413Fluoride, fluoride resistance and glycolysis in cultured cells. (Coauthor: Jan K. Hongslo) Acta Pharmacol. Toxicol. 1978, 43, 240-245Fluoride and energy metabolism in LS cells. (Coauthor: Jan K. Hongslo) Acta Pharmacol. Toxicol. 1979, 44, 347-349On the role of cyclic AMP in the cytotoxic effect of fluoride. (Coauthors: Jan K. Hongslo and Thoralf Christoffersen) Acta Pharmacol. Toxicol. 1980, 46, 66-72The effect of fluoride on the cellular uptake and pool of amino acids. (Coauthor: Jan K. Hongslo) Acta Pharmacol. Toxicol. 1979, 44, 354-358Fluoride inhibition of protein and DNA synthesis in cells in vitro. Acta Pharmacol. Toxicol. 1979, 45, 96-101Effect of sodium fluoride on protein and DNA synthesis, ornithine decarbox...

51Cr release cytotoxicity assay evaluated with fluoride and cadmium.

The sensitivity of the51Cr release assay was evaluated with two known cytotoxic agents; fluoride and cadmium. The sensitivity was far less than that of other assays, e.g. growth inhibition of cultured cells, and additionally a two-peaked dose-response curve was found with cadmium.

Strength and creep of dental amalgam: The effects of deviation from recommended preparation procedure

The effects of deviations from recommended preparation procedures on the compressive strength, modulus of elasticity, plastic deformation, toughness, and creep of four commercial amalgam alloys have been investigated. Deviations included changes in trituration time, mercury/alloy ratio, and condensation pressure. With regard to both compressive strength and creep, there were great differences in the susceptibility of different amalgam alloys to variations in manipulation. One conventional alloy showed almost no variation in compressive strength as a result of the deviations from the recommended preparation procedure. This material also showed much greater plastic deformation and fracture toughness than the other materials, making it less brittle and probably more resistant to bending forces. Dispersalloy exhibited both increased and decreased strength as a result of the deviations, while ANA 2000 and Revalloy only showed decreased strength. Some of the alterations for ANA 2000 and Revalloy resulted in a decrease in strength below an acceptable clinical level. Regarding the modulus of elasticity, only the conventional alloys were affected by the alterations in the preparation procedure. However, for the plastic deformation, the results were reversed; only the high-copper alloys were affected. The toughness of the specimens was decreased for all the alloys with the exception of one, which was insensitive to changes in the preparation procedure as far as compressive strength was concerned. One of the high-copper alloys showed the least change in creep relative to deviations in preparation procedures. Lowered condensation pressure increased the creep value for all the amalgams; and for the conventional alloys a lowered mercury/alloy ratio also resulted in increased creep.(ABSTRACT TRUNCATED AT 250 WORDS)

Cellular resistance to fluoride.

Cells cultured in vitro can be adapted to grow in the presence of high concentrations of fluoride by stepwise increasing the fluoride concentration in the culture medium. Such cells seem to have the ability to exclude fluoride from intracellular compartments.

Influence of variations in preparation of dental amalgam on dimensional stability and porosities

The susceptibility of amalgam to deviations in the preparation procedure produced an overall trend for both the setting dimensional stability and the number of porosities. The dimensional stability of ANA 2000 was the least affected by the deviations, while ANA 68 exhibited low susceptibility to the deviations when porosities are concerned. Lowered condensation pressure usually increased both the setting expansion and the number of porosities, and vice versa. Dispersalloy exhibited an increased number of porosities with both higher and lower condensation pressure. Except for ANA 2000, undertrituration caused increased expansion and porosities, while overtrituration resulted in increased contraction but minor effects on porosities. Lower mercury/alloy ratio increased the setting expansion and the number of porosities, while the response to a higher ratio was relatively small with the exception of a markedly increased setting expansion for ANA 68.

Porosities in a dental silver-palladium casting alloy

Twelve single crowns were cast in a silver-palladium alloy by six different casting techniques. Polished sections of the crowns were inspected and photographically recorded by light microscopy. The area of the inspected section of the casting and the number and area of pores were recorded on the photographs by means of a digitizing table connected to a microcomputer. A great number of defects were observed unevenly distributed in all castings. Only small variations were observed between the various casting techniques.

Influence of fluoride on the uptake of 51Cr-chromate by human erythrocytes.

Uptake of 51Cr-chromate by freshly collected human erythrocytes was inhibited by 90 mM sodium fluoride only in cells preincubated with fluoride. In vitro storage also increased the sensitivity of the cells: 90 mM NaF clearly inhibited the uptake of chromate in cells stored in vitro for 5 weeks. Gel chromatography revealed two forms of 51Cr within the cells, one of small molecular weight, which thin layer chromatography indicated was unchanged chromate; the other form was apparently bound to macromolecules such as hemoglobin.

Electrical activity in dental amalgam of submerged divers during welding

Divers performing underwater manual metal arc welding/cutting (UMMA) have complained about a metallic taste phenomenon. In several dives with voluntary leakage in their diving suits, potential alterations in dental amalgam were registered when they performed UMMA. Polarization resistance values were obtained for the test amalgam cylinders used and the divers dental restorations. These values, along with the recorded potential values of the amalgam test cylinders and of the divers dental restorations, enabled us to calculate the depolarizing current, using the law of Ohm. The current depolarizing the amalgam test cylinder did not differ significantly from the mean intermetallic currents between the dental restorations. The clinical effect of intraoral currents when performing UMMA welding should be regarded as small, whereas considerably higher currents should not be ruled out in an intense cutting situation.

Glucose consumption and lactate production in normal and fluoride adapted LS cells

The established cell line LS (mouse fibroblasts) has been adapted to grow at otherwise toxic concentrations of fluoride. Different substrains of adapted LS cells consumed less glucose and converted less of the glucose to lactate than the unadapted cells. Differences were also found in the two parameters dependent on the number of generations grown in the presence of fluoride. The more generations with fluoride, the less lactate was produced and the less glucose consumed.