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Biomedical subjects

M L Swartz

Publications and source records attributed to M L Swartz.

At least 55 records · Page 3Linked to original sources
PubMed1984

Long-term F release from glass ionomer cements.

Fluoride release from three commercial glass ionomer filling cements and three glass ionomer luting cements was measured in the laboratory over a 12-month period. Fluoride release from these glass ionomer cements was compared with that released from a silicate, silicophosphate, and a fluoride-containing polycarboxylate cement. The fluoride released from the glass ionomer cements throughout the one-year period was similar, both in quantity and pattern, to that released by the silicate cement. The silicophosphate cement tended to release fluoride in somewhat lesser amounts, while the amount of fluoride released by the polycarboxylate was negligible after the first few days. Analysis of these data indicates that these glass ionomer cements probably possess anticariogenic properties similar to those of silicate cement.

Chemical Phenomena↗
PubMed1983

The effects of enamel wear on the metal-porcelain interface.

This study evaluated the effects of wear of human tooth enamel on the metal-porcelain interface. Failure in the porcelain half of the specimens occurred only in specimens where the metal angle was 60 degrees. There was failure in one of four of the noble metal alloy specimens. With the base metal alloy specimens, in the first group two specimens showed cracks in the preparation stage while the other two showed no sign of cracks either before or after testing. In a second group of four base metal alloy specimens with a 60-degree angle, all four specimens showed cracks in the porcelain after glazing. These specimens were repaired by grinding out the cracks and filling them with porcelain. After wear-testing, all four specimens developed cracks. The data indicate that the acute angle of metal (60 degrees) at the metal-porcelain interface was more conducive to crack formation than were the other two angles tested. Therefore, in the case of a metal-ceramic restoration, with the occlusion on the metal, an acute angle of metal would not be appropriate. Furthermore, under clinical circumstances cracks that occur after glazing, as arose with the last four base metal alloy specimens (60 degrees), probably should not be ground out and refilled with porcelain. The results of this study indicate that such a practice in a clinical situation could lead to eventual fracture of the porcelain. The porcelain half of the specimens had a deeper and wider wear track than its metal counterpart, which indicated that the porcelain is less resistant than the metal to wear by enamel.(ABSTRACT TRUNCATED AT 250 WORDS)

Dental Alloys↗
PubMed1982

Dissolution of amalgam in saline solution.

This experiment was designed to investigate the in vitro corrosion of several modern dental amalgams in saline solution over a six-month period by measuring changes in the soluble corrosion products. Based on the change of the electrical conductivity of the solution, the dissolution rate seemed to decrease gradually for the first three to four months. Then a rapid increase was observed, indicating a reactivated corrosion process. Larger dissolutions of copper and mercury were observed, especially for the high copper alloys, in these later stages. Zinc and indium, if present, were preferentially released at the earlier stages. Silver and tin could not be detected. Evidence exists that the corrosion of tin results in insoluble deposits of corrosion products.

Copper↗
PubMed1980

In vivo measurements of thermal diffusion through restorations of various materials.

Temperature diffusion was monitored through in vivo restorations with and without bases 0.5 and 1 mm thick. Temperature diffusion was highest through amalgam restorations and slowest through unfilled resin restorations. The rate of diffusion through composite resins and silicate cement fell between the extremes. Bases of both zinc phosphate cement and zinc oxide-eugenol cement reduced the rate of temperature change on the floor of the cavity beneath amalgam restorations. The temperature change was generally less under the 1 mm base than the 0.5 mm base. Bases used beneath the nonmetallic restorations did not reduce the magnitude of temperature change on the cavity floor.

Acrylic Resins↗
PubMed1980

Rheology of luting cements.

A rheometer has been developed to simulate the extrusion of luting cement from beneath a full crown during seating using clinically realistic shear rates. Five luting cements were studied, and differences in rheological behavior were illustrated. These measurements demonstrate the importance of consideration of the effects of shear rate on viscosity when evaluating a cement for optimal clinical utilization.

Cold Temperature↗
PubMed1980

Fluoride distribution in teeth using a silicate model.

The fluoride determinations were done on enamel biopsies taken before and after restoration of extracted teeth with silicate cement. Two sites, one near the restoration and one 3 mm or more away from the restoration, were assayed. No difference was noted in pre- and post-restoration biopsies when teeth were restored with a fluoride-free silicate. Post-restoration biopsies at sites near and away from the restoration were significantly higher in fluoride as compared to pre-restoration biopsies when the teeth were restored with a fluoride-containing silicate.

Dental Cements↗
PubMed1979

The effect of relining on the accuracy and stability of maxillary complete dentures--an in vitro and in vivo study.

A technique was developed for evaluating in vitro the accuracy or fit of experimental denture bases using a low-viscosity impression material for determining the space between the master die and the processed denture base. These measurements indicated that relining heat-cured maxillary denture bases with autopolymerizing acrylic resin improved their adaptation to the ridges. Interestingly, if no teeth were present in the heat-cured denture base, markedly less distortion occurred after processing. Limited clinical measurements on the stability of maxillary dentures in function showed no statistically significant change in stability after relining, but the trend was toward increased stability with the relined denture.

Acrylic Resins↗
PubMed1979

Effect of composite resin bond agent on microleakage and bond strength.

A study was conducted to evaluate the efficacy of the bonding agents supplied with three composite resins in improving the sealing ability of the materials to tooth structure and the bond of the resins to enamel. When the enamel was not etched prior to insertion of the resin, the use of the bonding agents did not improve marginal seal. Little or no marginal leakage was detected when the restorations were placed by means of the acid etch technique, either with or without use of the respective bonding agents. A slight improvement in the bond of the resins to unetched enamel was secured by use of the bonding agents; however, this advantage was lost when the specimens were thermal cycled. Acid etching of the enamel significantly improved the bond of the strength of all three resins, both when the specimens were thermal-cycled and when stored at a constant temperature. Only one of the commercial bond agents enhanced the bond of its respective composite resin to etched enamel subjected to cycling.

Acid Etching, Dental↗