Restorations placed without the application of cavity varnish to the cavity walls and the cavosurface angle exhibited significant marginal leakage after 24 hours and 3 months. At the end of 6 months a decrease in leakage was exhibited with all alloys. With the exception of two specimens, restorations placed after coating the cavity walls and the cavo-surface angle with cavity varnish demonstrated slight or no marginal leakage at all time intervals. The results of this study indicate that the marginal leakage of a conventional filing alloy, a conventional spherical alloy, and two high-copper alloys are approximately the same. The corrosion-resistant high-copper alloys showed the same degree of marginal leakage as the conventional alloys. The results of this study agree with those of a previously reported in vitro study on amalgam leakage.

Animals↗

PubMed1978

Cyanoacrylate as a cavity liner for amalgam restorations.

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Acid Etching, Dental↗

PubMed1978

Film thickness of cements beneath complete crowns.

The results showed that Durelon, EBAC, zinc phosphate, Epoxylite CBA, and Fynal had thinner film thicknesses than EBA and Fluro-Thin. In addition, venting of a crown resulted in lower film thicknesses with all cements except Fynal and EBAC. No significant differences occurred with these two cements whether the crown was vented or not. Obviously many other factors besides film thickness, such as toxicity, strength, and solubility, have to be considered before selecting a cement for clinical use. When only film thickness is to be considered, all of the cements in the study could be recommended for the cementation of crowns with the exception of EBA and Fluoro-Thin.

Cementation↗

PubMed1978

The bactericidal potential of various endodontic materials for primary teeth.

An in vitro study of the bactericidal or bacteriostatic effects of several pulp therapy compounds and their components on selected bacterial commonly isolated from infected primary teeth was undertaken. It was determined that zinc oxide had no inhibitory effects on E. coli, Staph. aureus, and Strep. viridans; however, the addition of eugenol to this system retarded the growth of only the grampositive organisms. The inclusion of zinc acetate as a setting accelerator inhibited both gram-positive and gram-negative bacteria. Also the inhibitory effects on these three organisms could be greatly enhanced by the addition of formocresol or paraformaldehyde to the zinc oxide--eugenol--zinc acetate system. It was also noted that Sargenti's N-2 paste was apparently no more effective in retarding growth of these organisms than the mixtures. Only the lead tetroxide and hydorcortisone present in the N-2 paste was toxic to the Staph. aureus but not to E. coli or to Strep. viridans. The other heavy metals in N-2 apparently have no antibacterial activity in the manner in which they were tested. This evidence suggests, but is not conclusive, that zinc oxide--eugenol--zinc acetate, with or without formaldehyde-containing compounds, may be effective in the elimination of bacteria from pulpotomized primary teeth. Therefore, the addition of highly cytotoxic chemicals which will remain sealed in a root canal and be active for extended periods of time may not be necessary for successful treatment.

Anti-Bacterial Agents↗

PubMed1978

Microleakage of several class V anterior restorative materials: a laboratory study.

The study was designed to evaluate the marginal leakage of abraded gingival areas in extracted teeth using five anterior composite resin acid-etch restorative materials and a glass ionomer cement, ASPA. In using three of the composite resin restorative materials, Simulate, Cervident, and Concise, there was a layer of unfilled resin between the etched tooth surface and the composite resin. Restodent and Enamelite were placed directly on the etched tooth surface. The results of the study indicate that there is a significantly greater degree of marginal leakage at the gingival margin than there is at the occlusal or incisal margin of composite restorations. In addition, greater marginal leakage was observed in those restorations where no layer of unfilled resin was placed between the etched tooth surface and the composite resin. The glass ionomer cement showed no marginal leakage at intervals of one day, three months, and six months; however, a small amount of leakage was observed at the incisal or occlusal and gingival margins at a year on half of the autoradiographs. A study has been initiated to determine leakage patterns around composite resin restorations placed in teeth with naturally occurring cervical erosion or abrasion.

Acrylic Resins↗

PubMed1978