Biomedical subjects

J Vaidyanathan

Publications and source records attributed to J Vaidyanathan.

6 recordsLinked to original sources

PubMed1992

Thermoanalytical characterization of visible light cure dental composites.

Selected commercial and experimental composites and resin systems have been evaluated by thermal analysis techniques of Differential Scanning Calorimetry, Thermogravimetric Analysis and Thermomechanical Analysis. Important thermal data such as heat of cure, coefficient of thermal expansion, dimensional changes over selected temperature ranges, filler weight percent, onset temperature of decomposition, etc. have been determined. Heat of cure, thermal expansion coefficient and dimensional changes appear to follow an inverse linear regression fit with filler fraction in the composite. Thermal expansion changes and exothermic reactions with temperature indicate secondary cure during postcure heating. The thermally-induced decomposition occurs in multiple stages indicating presence of different structural species in the resin matrix.

Bisphenol A-Glycidyl Methacrylate↗

PubMed1991

Tarnish of dental alloys by oral microorganisms.

Five dental alloys, on exposure to blood and chocolate media with and without inoculated microorganisms, showed varying degrees of tarnish. The results indicated a composition-dependent tarnish behavior of alloys in microorganism-inoculated media, indicating a potential role for the oral microorganisms in inducing clinically observed tarnish of dental alloys. Actinomyces viscosus and periodontal pocket specimens show a similarity in their activity to induce tarnish in base metal-containing dental alloys.

Actinomyces viscosus↗

PubMed1991

Direct post and core pattern made with light-curing composite resin.

An unfilled Bis-GMA composite resin can be used advantageously for making an accurate cast post and core pattern. The technique is faster and easier than normal pattern fabrication methods using an unfilled acrylic resin, wax, or a combination of the two.

Bisphenol A-Glycidyl Methacrylate↗

PubMed1991

Computer-controlled differential scanning calorimetry of dental composites.

In this paper, computer-controlled differential scanning calorimetry has been used to evaluate the heat liberated and the temperature rise associated with the light cure of selected dental composites. In addition, the effect of postcure heating and increased ambient temperature of light cure are examined in terms of potential secondary cure. The results indicate significant differences between the mean heats of cure of different composites, primarily reflecting the filler fraction variations of the composites. In addition, increased cure activity appears to result from both postcure heating as well as thermal activation due to higher ambient temperature of light cure. The results are analyzed and attributed to variations in resin phase composition and resin content per unit weight of composite as well as thermally induced enhancement of cure.

Calorimetry, Differential Scanning↗

PubMed1990

Interactive effects of etching and pre-oxidation on porcelain adherence to non-precious alloys: a guided planar shear test study.

Interactive effects of etching and pre-oxidation on porcelain adherence to non-precious alloys were studied by a guided planar shear bond test under non-cantilever conditions. The results indicated that electrolytic etching decreases bond strength, but that oxidation of etched surfaces restores the bond strength level. The results are explained by a hypothesis that depletion of critical elemental species occurs during etching. Potential replenishment of the lost elements during subsequent oxidation, although not confirmed, may assist in improving bond strength.

Acid Etching, Dental↗

PubMed1989

Evaluation of the ability of glass-ionomer cement to bond to glass-ionomer cement.

This study investigated the cohesive bond strengths of glass-ionomer cement at three setting and etching intervals and compared these bonds to the shear strength of the material itself. Bonded cylinders were created and then sheared using the Instron Universal Testing Machine. Analysis of bond values of glass ionomer added to glass ionomer indicate bond variability and low cohesive bond strength of the material. Bond values of unbonded glass-ionomer material indicate that the material itself is stronger than bonds established between bonded samples.

Dental Bonding↗