Kozo Horie

The influence of surface conditions and silane agents on the bond of resin to dental porcelain

The influence of porcelain surface condition and the application of silane agents on the adhesion between resin and dental porcelain were investigated. The experimental variables included three porcelain surface preparations, as polished, etched with phosphoric acid, or etched with hydrofluoric acid and three kinds of commercially available silane coupling agents. The shear bond strength between the light-cured composite and the dental porcelain was measured after one-day immersion in 37 degrees C water. Samples without the silane agent application were also tested as controls. Without the silane agent, hydrofluoric acid-etched specimens had a higher bond strength than polished or phosphoric acid-etched specimens. The combination of hydrofluoric acid-etching and an application of Cosmotech Porcelain Primer increased the bond strengths more than that of phosphoric acid-etching. With the application of Laminabond Porcelain Primer or Optec Silane Coupling Agent, high bond strengths were obtained regardless of the porcelain surface condition. Therefore, it seems the chemical reactions between the porcelain surface and silane agents were responsible for the high shear bond strengths.

A Comparison of the Tensile Bond Strengths of Composite Resins to Longitudinal and Transverse Sections of Enamel Prisms in Human Teeth

The tensile bond strengths of composite resins to transverse and longitudinal sections of enamel prisms etched with phosphoric acid were examined. The tensile bond strengths were 18-19 MPa to the transverse and 10-11 MPa to the longitudinal sections and thus were influenced by the nature of the enamel crystal planes. These facts suggest that composite resin restorations will have a longer life span if the enamel walls are given marginal forms to produce transverse rather than longitudinal sections of enamel prisms.

Adsorption behavior of a silane coupling agent onto a colloidal silica surface studied by 29Si NMR spectroscopy

Abstract The adsorption mechanisms of a silane coupling agent onto a colloidal silica surface are investigated by means of 29 Si NMR and compared with previous spin-labeled ESR data. The dimer species are found to be the predominant species adsorbed onto a colloidal silica surface in silane solution. The adsorption behavior shows a dependence on the concentration of the silane coupling agent used. At low concentrations, the silane coupling agent appears to be adsorbed in regular fashion, while at higher concentrations, it is adsorbed in random fashion.

Condensation behavior of a sulane coupling agent in the presence of colloidal silica studied by 29Si and 13C NMR

Abstract The hydrolysis and condensation mechanisms of a silane coupling agent in the presence of colloidal silica were investigated with 29Si and 13C NMR. The influence of colloidal silica on the reaction is acceleration of the hydrolysis of the methoxy group of the silane coupling agent and, conversely, deceleration of the condensation of the hydrolyzed species. After 56 days, the main products are oligomeric species in the presence of colloidal silica, although mainly polymeric species are produced when the colloidal silica is absent. These results may derive from the acidic character of the colloidal silica.

Effect of water-soluble photoinitiator on the adhesion between composite and tooth substrate.

The effectiveness of a water-soluble photoinitiator in a dentin primer was examined by measuring the tensile bond strength between the composite and tooth substrate treated with the primer. The water-soluble photoinitiator, 2-hydroxy-3-(3,4 dimethyl-9-oxo-9H-thioxanthen-2-yloxy)-N,N,N-trimethyl-1- propanaminium chloride (QTX) was dissolved into an aqueous solution of methoxy-nonaethyleneglycol monomethacrylate (M9G) or poly-N-vinylpyrrolidone (PNVP), and these aqueous solutions were used as primers. The combination of 0.5 M EDTA pretreatment and 1% QTX -35% PNVP aqueous solution priming produced the highest bond strength. A mixture of dentin fractures and interfacial failure between the dentin and the resin was observed in the test specimen. This dentin priming combination was also effective in improving the bond strength to enamel pretreated with EDTA.

Adhesion of composite to polished dentin retaining its smear layer.

OBJECTIVES This study was designed to measure the adhesion of a composite to the smear layer. METHODS An experimental aqueous bonding agent was supplied in the form of two liquids. One contained methacryloyl tyrosine amide (MTYA), glyceryl methacrylate (GM), dimethylaminoethylmethacrylate and benzene sulfinic acid sodium salt, and the other contained glutaraldehyde, succinic acid and 2-hydroxy-3-(3,4-dimethyl-9-oxo-9H-thioxanthen-2-yloxy)-N,N, N-trimethy-1-propanaminium chloride (QTX). QTX is a unique water-soluble photo polymerization initiator. The application times and irradiation times of the experimental aqueous bonding agent were varied. RESULTS The highest mean bond tensile strength was obtained by irradiating the bonding agent for 1 min. A 3 min irradiation decreased the mean bond strength when the bonding agent was applied to the polished dentin surface for 1, 3 or 5 min. The mean values resulting from the application of experimental aqueous bonding agent were higher than those from a commercially available bonding agent which preserved or modified the smear layer. There was a significant decrease in the bond strength after 500 or 2000 thermocycles in specimens with a 5 min application of the bonding agent, but there was no significant decrease in the bond strength when the application time was for 1 or 3 min. SEM observation showed the formation of a hybrid layer with a thickness of approximately 1-1.5 micrometers. SIGNIFICANCE The aqueous bonding agent tested in this investigation was capable of penetrating the smear layer and the bond strength exceeded the values obtained by bonding agents that remove the smear layer.