Antibacterial effects of amalgams on mutans streptococci in an in vitro biofilm test procedure.

Conflicting data continue to be presented in the literature regarding the antibacterial potential of various amalgam alloy compositions. The aim of the present study was to compare the antibacterial effects of 4 different amalgam samples on mutans streptococci using two in vitro test procedures. Glass and bovine enamel served as negative controls.

Effects of warm air-drying and spreading on resin bonding.

The purpose of this study was to compare the effect on resin-to-enamel bonding produced by warm air from a hair dryer, and to correlate changes in resin bond strength with resin tag structure. Herculite-XR resin composite and Bondlite bonding resin were used. The three technique variables were the type of air used for drying, air dryer distance, and drying and spreading time.

Effects of warm air-drying on intra-pulpal temperature.

This study was designed to determine what effects different warm air-drying conditions have on the intra-pulpal temperature (IPT), with or without chamber preparation and with or without an acid-etching treatment of the enamel. Four human maxillary centrals and four cuspids had lingual access openings prepared to accommodate a thermal sensor probe. Half of the specimens received a labial chamber preparation and half were acid-etched.

Mechanical tests of smooth silver-plated retention pins in amalgam.

Retention and stress concentration factors can be improved if a good mechanical bond exists between smooth retention pins and an amalgam restoration. It is shown that, by silver-plating pins and by using a rubbing technique during condensation of the amalgam, a good mechanical bond is produced. Mechanical tests of this bond show that its shear strength is adequate to withstand the stresses likely to be produced by occlusal forces.

Microscopic study of smooth silver-plated retention pins in amalgam.

A silver-plating technique was developed in an effort to produce good mechanical bonding characteristics between stainless steel pins and amalgam. Metallographic microscope and scanning electron microscope (SEM) studies were made to assess the presence, or otherwise, of such a bond between (a) the silver layer plating and the surface of the stainless steel pins, and (b) and silver plating and the amalgam. Unplated stainless steel and sterling silver pins were used as a control and as a comparison, respectively.

A photoelastic study of stress concentrations produced by retention pins in amalgam restorations.

Photoelastic models of pin-amalgam restorations were constructed to simulate different pin-dentin-amalgam relationships. The stress-raising effect of a pin is influenced by the axial stiffness of the pin and its capability of bonding with the amalgam. The stress produced by a very stiff non-bonded pin could cause failure of the restoration.

Axial stiffness of retention pins in human dentin.

Axial deflections of pins, anchored in specimens of human dentin by five different procedures, were measured by a specially constructed apparatus to an accuracy of 0.1 mu. Axial stiffness values calculated from these measurements were found to be significantly different for different methods of anchorage.

A laboratory evaluation of the effect of two surface-wetting treatments on soft denture liners.

The wettability of acrylic and silicone soft denture-liners was improved by two methods of surface treatment. They consisted of formation of a thin film of silica from the application of silicon tetrachloride, and by cross-linking the surface molecules and bombarding with hydroxyl free radicals. Softness and water sorption were monitored throughout the study.