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Biomedical subjects

H J Prosser

Publications and source records attributed to H J Prosser.

At least 19 recordsLinked to original sources
PubMed1988

Long-term monitoring of microleakage of dental cements by radiochemical diffusion.

Radioactive 14C sucrose was found to be an ideal marker for microleakage because it did not penetrate tooth tissue, dental cement, or mounting resin. The main finding is that the adhesive cements--the glass-ionomer and polycarboxylate--are significantly more effective at preventing microleakage than are the traditional phosphate cements--silicate and zinc phosphate. The differences can be as high as two orders of magnitude. The adhesive cements provide almost perfect and reliable seals. By contrast, the nonadhesive cements are erratic sealants with most of the restorations leaking.

Carbon Radioisotopes↗
PubMed1986

Adhesion of carboxylate cements to hydroxyapatite. I. The effect of the structure of aliphatic carboxylates on their uptake by hydroxyapatite.

An investigation was made into the effect of the structure and functionality of aliphatic carboxylates on their sorption onto hydroxyapatite with a view to ascertaining factors affecting the adhesion of polyacrylate cements to tooth materials. In general, the amount of carboxylate sorbed was found to increase with the number of groups contained in the molecule. Thus, polyacrylate was found to be much more strongly sorbed than low molecular weight species. Sorption of the low molecular weight species appeared to be related to stereochemical factors rather than to the stability constants of their calcium chelates.

Adsorption↗
PubMed1986

Glass-ionomer cements of improved flexural strength.

The effect of glass and polyacid composition on cement strength has been investigated with a view to improving the glass-ionomer cements. The flexural strength of glass-ionomer cements was found to be greatly dependent on the glass and polyelectrolyte used to prepare them. Opaque and opal glasses containing crystallites tended to yield cements with high flexural strength. Flexural strength was also found to be increased by increasing the molecular weight of the polyacid. In water-setting systems, cement strength was shown to be critically dependent on the glass/polyacid ratio.

Acrylates↗
PubMed1985

Reaction cements as materials for the sustained release of trace elements into the digestive tract of cattle and sheep. I. Copper release.

Acid-base reaction cements were produced by reacting copper oxide with phosphoric acid. When placed in the reticulo-rumen of cattle and sheep these cements released copper into the digestive tract for at least 3 months at a rate sufficient to provide the animals' requirements for copper. Lambs given a pellet of cement at 3 months of age had significantly greater concentrations of copper in their livers than similar untreated animals when slaughtered 3-4 months later. It was shown that salts of cobalt and selenium could be incorporated into the cement to provide additional supplementation with these two elements.

Animals↗
PubMed1983

Mechanism of adhesion of polyelectrolyte cements to hydroxyapatite.

The interaction between polyacrylate ions and hydroxyapatite was examined using extraction techniques and infra-red spectroscopy. These studies have shown that polyacrylate ions become irreversibly attached to the surface of hydroxyapatite by displacing existing phosphate ions. The mechanism is not one of simple ion exchange, since calcium ions are displaced by the phosphate ions.

Acrylic Resins↗
PubMed1983

The cement-forming properties of phytic acid.

The properties of aluminosilicate-phytic acid cements were investigated. They proved to be fast-setting and resistant to acid attack, with the ability to bond to enamel, but not to dentin.

Adhesiveness↗
PubMed1982

NMR spectroscopy of dental materials. I. 31P studies on phosphate-bonded cement liquids.

Phosphorus-31 nuclear magnetic resonance spectroscopy of phosphoric acid solutions containing zinc and aluminium indicates that zinc forms simple salts in solution, whereas aluminium forms a number of complexes, some of which are polymeric. The formation of the aluminophosphoric acid complexes controls the gelation and strengthening of the dental silicate cement and prevents the formation of crystalline zinc phosphate in the zinc phosphate cement.

Aluminum↗