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 examination has been made of factors affecting the results obtained from the impinging jet method for evaluating the durability of dental cements. These included intrinsic factors i.e. the powder/liquid ratio used in the mix and the cure time of the cement and extrinsic factors i.e. the pH, ionic strength and temperature of the test solutions. The method was found to be sensitive to test conditions. The initial rate of erosion was found to be essentially constant.
Subject(s)
Dental Cements , Evaluation Studies as Topic , Humans , Hydrogen-Ion Concentration , Osmolar Concentration , TemperatureABSTRACT
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
An extensive review has been made of the impinging jet method for evaluating the durability of dental cements. A comprehensive range of 28 dental cements was examined. The initial rate of erosion was found to be essentially constant. Zinc oxide cements were found to be markedly less durable than alumino-silicate cements. Results broadly correlate with those found in clinical studies.
Subject(s)
Dental Cements , Glass , Polycarboxylate Cement , Silicate Cement , Stress, Mechanical , Structure-Activity Relationship , Zinc Oxide-Eugenol Cement , Zinc Phosphate CementABSTRACT
A study has been made on improving the adhesion of a glass ionomer cement by the chemical treatment of dentin and enamel surfaces. The most effective surface conditioners were high molecular weight substances containing a multiplicity of functional groups capable of hydrogen bonding. Low molecular weight chelating agents which dissolve calciferous material and dramatically alter the surfaces of enamel and dentin are less effective.
