ABSTRACT
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.
Subject(s)
Dental Cements , Dental Leakage/diagnosis , Dental Restoration, Permanent , Carbon Radioisotopes , Dental Bonding , Dental Enamel , Diffusion , Glass Ionomer Cements , Humans , Polycarboxylate Cement , Silicate Cement , Sucrose , Time Factors , Zinc Phosphate CementABSTRACT
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.
Subject(s)
Dental Cements , Hydroxyapatites , Adsorption , Calcium , Carboxylic Acids , Durapatite , Hydrogen-Ion Concentration , Molecular Weight , Phosphates , Structure-Activity RelationshipABSTRACT
Novel acid-base reaction cements have been developed for use as controlled release formulations. Many new ones have been discovered and assessed; these include those which are capable of releasing copper, cobalt or selenium singly or in combination. A selection was made of the most suitable formulations for this purpose and these were subjected to field trials.
Subject(s)
Delayed-Action Preparations , Trace Elements/administration & dosage , Animals , Biocompatible Materials , Cattle , Cobalt/administration & dosage , Copper/administration & dosage , Hydrogen-Ion Concentration , Rumen , Selenium/administration & dosage , Sheep , Time FactorsABSTRACT
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.
Subject(s)
Dental Cements , Glass Ionomer Cements , Acrylates/analysis , Aluminum Silicates/analysis , Carboxylic Acids/analysis , Dental Cements/analysis , Elasticity , Glass/analysis , Glass Ionomer Cements/analysis , Polyethylenes/analysis , Stress, Mechanical , Tensile StrengthABSTRACT
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.
Subject(s)
Cattle/metabolism , Copper/administration & dosage , Digestive System/metabolism , Sheep/metabolism , Animals , Copper/metabolism , Delayed-Action Preparations , Female , Phosphoric Acids , SolubilitySubject(s)
Dental Materials , Biocompatible Materials , Calcium Hydroxide , Calcium Sulfate , Child , Composite Resins , Dental Bonding , Dental Caries/prevention & control , Dental Impression Materials , Dental Leakage , Denture Bases , Fluorides/administration & dosage , Glass Ionomer Cements , Humans , Maxillofacial Prosthesis , Models, Dental , Pit and Fissure Sealants/therapeutic use , Resins, Synthetic , Root Canal Filling Materials , Silicate Cement , Zinc Oxide-Eugenol CementSubject(s)
Dental Cements , Acrylic Resins , Biocompatible Materials , Chemical Phenomena , Chemistry, Physical , Diffusion , Glass Ionomer Cements , Humans , Silver , SolubilitySubject(s)
Dental Materials , Acrylic Resins , Biomechanical Phenomena , Composite Resins , Dental Amalgam , Dental Articulators , Dental Cements , Dental Leakage/etiology , Dental Restoration, Permanent , Dentures , Humans , Orthodontic Appliances , Root Canal Filling Materials , Surface PropertiesABSTRACT
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.
Subject(s)
Acrylic Resins , Hydroxyapatites , Adhesiveness , Chemical Phenomena , Chemistry, Physical , Spectrophotometry, Infrared , Surface PropertiesABSTRACT
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.
