XPS study on the weakest zone in the adhesion structure between resin containing 4-META and precious metal alloys treated with different surface modification methods

Trace of organic sulfur compounds detected from debonded interface between transparent acrylic resin and gold alloy

The purpose of the current study was to evaluate the bonding performance of two single-liquid primers, which contained 6-(4-vinylbenzyl-n-propyl) amino-1,3,5-triazine-2,4-dithione (VTD) or 6-methacryloyloxyhexyl 2-thiouracil 5-carboxylate (MTU-6), used for bonding between metals and an acrylic resin. A gold alloy and high-purity titanium were used as adherend materials, and a transparent acrylic resin initiated with tri-n-butylborane derivative was selected as the luting material. Both adherends were treated with one of the primers and bonded with the luting material, after which shear bond strength was determined. Fourier transform infrared spectroscopy was used to analyze debonded resin specimens. Shear bond strength to gold alloy was significantly greater than that to titanium for both the VTD and MTU-6 primers. A trace of thiol structure, probably derived from VTD and MTU-6, was detected on resin surfaces debonded from gold alloy. These results indicate that the two organic sulfur compounds, which are stable in an atmospheric environment, are tautomerized into a thiol structure, thus allowing adsorption onto noble metals. In addition, the adsorbed thiol compounds contribute to chemical bonding between the acrylic resin and noble metal alloy, as polymerizable adhesive functional monomers.

Acid Etching of Titanium for Bonding with Veneering Composite Resins

Commercially pure titanium (cpTi) was etched using three concentrated acids: 18% HCl, 43% H3PO4, and 48% H2SO4. The bond strengths between five types of veneering composite resin and eight cpTi treatments (involving combinations of sandblasting, acid etching in 48% H2SO4, and vacuum firing) were determined before and after 10,000 and 20,000 thermal cycles. There were no significant differences in the bond strength of resin to cpTi after etching in 48% H2SO4 at 90 degrees C for 15 minutes, at 60 degrees C for 15, 30, or 60 minutes, and after sandblasting with and without vacuum firing (p > 0.05); moreover, these treatments yielded the highest values. As for vacuum firing, it had no significant effect on resin bond strength to cpTi before or after 10,000 and 20,000 thermal cycles. We therefore concluded that acid etching in concentrated H2SO4 is a simple and effective surface modification method of titanium for bonding to veneering composite resins.

Clinical longevity of resin-bonded bridges bonded using a vinyl-thiol primer

The purpose of this study is to clinically confirm the adhesive effect of a vinyl-thiol primer (V-Primer) for precious alloys. Further, we examined the failure of resin-bonded bridges (RBBs) in order to improve the clinical longevity of RBBs, and to analyse the causes of failure. Twenty-six RBBs were bonded with V-primer and Super Bond C & B between May 1987 and December 1997 in the Dental Clinic of the Health Sciences University of Hokkaido. The RBBs were made of silver-palladium-gold alloy or metal-ceramic gold alloys. V-primer was effective in bonding Super Bond C & B to the RBBs made of silver-palladium-gold alloys. Ten prostheses had functioned satisfactorily for 8-11 years. However, six of the 26 RBBs had become detached. In four of the six failed RBBs, the type of bond failure was a mixture fracture in the resin-enamel interface. Our results suggest that: (1) V-primer is effective on RBBs made of silver-palladium-gold alloys. (2) Mechanical retention is necessary for retainers to improve the longevity of RBBs when the V-primer is applied to RBBs made of precious alloys without copper. (3) The RBB should not be applied to abutment teeth that have differences in tooth mobility.

Effect of alkaline treatment of pure titanium and its alloys on the bonding strength of dental veneering resins

Commercially pure titanium (cpTi), Ti6Al4V, an experimental beta-type titanium (Ti 53.4 wt%, Nb 29 wt %, Ta 13 wt %, and Zr 4.6 wt %), and 12% AuPdAg alloy plates were sandblasted, cleaned in water, and dried. cpTi plates were treated with nine alkaline treatments that differed in the type of alkali, alkaline concentration, soaking temperature, soaking time, and heating temperature. cpTi plates that were only sandblasted or sandblasted and oxidized at 600 degrees C for 1 h in air were also prepared. Finally, the bonding strengths of 11 kinds of surface-treated cpTi to resin were measured using a pull-shear bonding method after immersion in physiologic saline solution at 37 degrees C for 24 h. The bonds of the standard alkaline-treated cpTi and two titanium alloys to resins were 1.5-1.9 times stronger than those of sandblasted specimens (p < 0.01), but no significant effects of the alkaline treatment were observed on the 12% AuPdAg alloy. The greatest bonding strengths were found for cpTi treated with NaOH and KOH and then heated at 600 degrees C (p < 0.01). In conclusion, alkaline treatment is a simple, effective surface modification of titanium that improves bonding to veneering resin.

Raman and IR studies on adsorption behavior of adhesive monomers in a metal primer for Au, Ag, Cu, and Cr surfaces

6-[N-(4-vinylbenzyl)propylamino]-1,3,5-triazine-2,4-dithione (VBATDT) and 10-methacryloyloxydecyl dihydrogen phosphate (M10P) are functional monomers used for the surface treatment of dental alloys. The aim of our study was to clarify the role of a commercial metal primer containing both the monomers in adhesion between resin and various dental metals on a molecular level. We used surface-enhanced Raman scattering (SERS) and infrared reflection absorption (IRA) spectroscopy. An SERS measurement was performed with a 647 nm laser line for a mixture of aqueous Au colloid and the primer. IRA spectra were taken for cast films of the primer on Au, Ag, Cu, and Cr surfaces as a function of rinse time, and for self-assembled monolayer (SAM) films from dilute mixed solution of VBATDT and M10P. These spectra indicate that VBATDT in the primer is mainly chemisorbed on Au, Ag, and Cu surfaces with respect to thickness, whereas only M10P is adsorbed on Cr. We also examined the tensile bond strengths between resin and Au, Ag, Cu, and Cr plates treated by VBATDT, with and without M10P, and found that VBATDT effectively promotes the bond strength between resin and the metals except for Cr, whereas M10P is effective only for Cr. These adhesion characteristics are consistent with the chemisorbed species on each metal surface as shown in the spectroscopic evidence.