Junko Satou

In vitro color change of composite-based resins

The adsorption of staining materials to resin restoratives was considered to be influenced by the physico-chemical properties of the resin-based monomers. To study the effects of the surface characteristics of resins on staining, we prepared five visible-light-cured experimental resins without fillers. Staining of these resins was colorimetrically measured. The staining solutions used were the Oil Orange and the Food Red 3 solutions. With the Oil Orange solution, the materials with higher hydrophobicity showed higher staining. With the Food Red 3 solution, the materials with higher water sorption showed higher staining.

Effects of various finishing methods on staining and accumulation of Streptococcus mutans HS-6 on composite resins

Abstract Microfilled and conventional composite resins, polished by different methods were tested for their staining and for bacterial accumulation in vitro. All 4 composite resins showed their characteristic staining tendencies for either Tobacco or Oil orange depending on their physicochemical properties and surface roughness. The effect of these factors seemed to depend on the substance adsorbed and the nature of the resins. Thus, in Tobacco solution immersion test, white point-polished surface showed the highest value of staining, which was followed by smooth surface and finished surface in this order, except one (Clearfil), in which the order was reversed. In the Oil orange solution immersion test, staining tendencies showed little correlation with surface roughness, but the hydrophobicity of the resin seemed to be an important factor. Polished surface accumulated more bacteria than smooth surface in the in vitro test of bacterial accumulation. However, no appreciable difference was observed among these 4 resins having an equal roughness.

Streptococcal Adherence on Various Restorative Materials

The adherence of Streptococcus sanguis ATCC 10556, S. sanguisATCC 10557, S. mutans Ingbritt, and S. mutans OMZ 176 to the surfaces of composite resins, amalgam alloys, and a Au-Ag-Pd alloy was measured. Adhesion was correlated with values for hydrophobicity and ζ-potential of the bacteria and the restorative materials. The hydrophobicity of the restoratives showed a positive correlation between the numbers of adherent S. sanguis cells, suggesting that hydrophobic interactions are important for the adherence of this bacterial species. In contrast, the numbers of adherent S. mutans cells showed a positive correlation with the ζ-potential of the restoratives, suggesting that electrostatic interactions are important in adherence of this bacterium.

Clinical evaluation of two posterior composite resins retained with bonding agents

Two hundred thirteen carious cavities were restored with two brands of chemically adhesive posterior composite resins by totally etching both the enamel and dentin walls after removing only the caries detector-stainable tissue and with no mechanical retention form in the cavity preparation. Most cavities were extensive, involving more than two surfaces in 74%. The dentin floor was not covered with cement although a spot lining was placed when the cavity was deep. All restorations were examined, usually after 4 years, by photographs and scanning electron microscope observation of replicas, and by criteria established by the U.S. Public Health Service. The materials and the technique proved to be clinically useful.