Fifteen-year clinical performance of a resin-bonded fixed partial denture seated with a thione primer and a tri-n-butylborane-initiated luting agent

Adhesive bonding of noble metals with a thiohydantoin primer

OBJECTIVE

The purpose of this study was to assess the effects of an experimental primer containing acetone solution and a sulfur-containing functional monomer, 10-methacryloyloxydecyl-(2-thiohydantoin-4-yl)propionate (MDTHP), on the bonds between noble metals and acrylic resin.

METHODS

The experimental primer used as the control for comparison consisted of 6-(4-vinylbenzyl-n-propyl)amino-1,3,5-triazine-2,4-dithione (VBATDT) in acetone. These primers were prepared as equimolar functional monomers (0.1 mol%). A self-polymerizing acrylic resin initiated with tri-n-butylborane (TBB) was used as the luting agent. Four elemental metal disks (silver, copper, palladium, and gold) were used as adherend specimens. All the disks were wet-ground with silicon carbide paper (#1500). Bonding reactions were performed on 12 combinations of the four metals, and the disks were either primed with MDTHP or VBATDT or were unprimed (control). Shear bond strengths were determined pre- and post-thermocycling (5-55 °C, dwell time 60 s, 20,000 cycles). The results were statistically analyzed via a non-parametric test (α = 0.05).

RESULTS

The post-thermocycling shear bond strengths of the MDTHP primer were as follows (median, n = 11): 13.2 MPa on silver, 25.9 MPa on copper, 4.1 MPa on palladium, and 11.3 MPa on gold. The MDTHP primer showed higher post-thermocycling shear bond strength on all the four metals. Additionally, on silver and copper, the MDTHP bond strengths were higher than on the other metals.

SIGNIFICANCE

Within the limitation of current of experimental setting, the MDTHP compound may be applicable as a functional monomer for bonding noble metal alloys.

Molecular Modulation of Fetal Liver Hematopoietic Stem Cell Mobilization into Fetal Bone Marrow in Mice

Development of hematopoietic stem cells is a complex process, which has been extensively investigated. Hematopoietic stem cells (HSCs) in mouse fetal liver are highly expanded to prepare for mobilization of HSCs into the fetal bone marrow. It is not completely known how the fetal liver niche regulates HSC expansion without loss of self-renewal ability. We reviewed current progress about the effects of fetal liver niche, chemokine, cytokine, and signaling pathways on HSC self-renewal, proliferation, and expansion. We discussed the molecular regulations of fetal HSC expansion in mouse and zebrafish. It is also unknown how HSCs from the fetal liver mobilize, circulate, and reside into the fetal bone marrow niche. We reviewed how extrinsic and intrinsic factors regulate mobilization of fetal liver HSCs into the fetal bone marrow, which provides tools to improve HSC engraftment efficiency during HSC transplantation. Understanding the regulation of fetal liver HSC mobilization into the fetal bone marrow will help us to design proper clinical therapeutic protocol for disease treatment like leukemia during pregnancy. We prospect that fetal cells, including hepatocytes and endothelial and hematopoietic cells, might regulate fetal liver HSC expansion. Components from vascular endothelial cells and bones might also modulate the lodging of fetal liver HSCs into the bone marrow. The current review holds great potential to deeply understand the molecular regulations of HSCs in the fetal liver and bone marrow in mammals, which will be helpful to efficiently expand HSCs in vitro.

Effect of multi-purpose primers on the bond durability between tri-n-butylborane initiated resin and gold alloy

PURPOSE

This study investigated the influence of an interaction between sulfur-containing monomers and other monomers in multipurpose primers on the bond durability of a tri-n-butylborane (TBB)-initiated acrylic resin to a gold alloy.

METHODS

The disk-shaped adherend materials were prepared from a gold alloy (Casting Gold M.C. Type IV). Two multipurpose-primers (Universal Primer, Monobond Plus), four metal primers containing an organic sulfur compound (M.L. Primer, Alloy Primer, Metaltite, and V-Primer), and three acidic primers (Estenia Opaque Primer, Acryl Bond, and Super-Bond Liquid) were used. The shear bond strengths were determined pre- and post-thermocycling to evaluate the bond durability. A statistical analysis of the results was performed using a non-parametric procedure, and the cohesive failure ratios of the debonded surfaces were compared.

RESULTS

Among the pre-thermocycling groups, M.L. Primer, Metaltite, Monobond Plus, Universal Primer, and Alloy Primer showed the greatest bond strengths. Among the post-thermocycling groups, M.L. Primer, Metaltite, Monobond Plus, and Universal Primer showed the greatest bond strengths, whereas Acryl Bond, Super-Bond Liquid, Estenia Opaque Primer, and the unprimed control showed the lowest. Similarly, the primers that did not contain either a sulfur compound showed an obvious reduction in the cohesive failure ratio.

CONCLUSIONS

Multi-purpose primers containing a sulfur-containing monomer increased the bond strength of a TBB-initiated acrylic resin to a gold alloy. The proportion of the area of cohesive failure to the bonded area showed an interrelationship with the shear bond strength testing results.

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.

Effect of different surface treatments and retainer designs on the retention of posterior Pd-Ag porcelain-fused-to-metal resin-bonded fixed partial dentures

The aim of this study was to investigate the adhesive property of palladium-silver alloy (Pd-Ag) and the simulated clinical performance of Pd-Ag porcelain-fused-to-metal (PFM), resin-bonded, fixed partial dentures (RBFPDs). A total of 40 Pd-Ag discs (diameter=5 mm) were prepared and divided into the following four groups (n=10): a) No sandblasting, used as a control; and b, 50 µm; c, 110 µm; and d, 250 µm aluminum oxide (Al₂O₃) particles, respectively. Another 50 discs were pre-sandblasted and divided into five groups (n=10) subjected to different treatments: e) Sandblasting, used as a control; f) silane; g) alloy primer; h) silica coating + silane and i) silica coating + alloy primer. All 90 discs were bonded to enamel with Panavia F 2.0 and then subjected to shear bond strength (SBS) testing. The fracture surfaces were examined by scanning electron microscopy. Next, 40 missing maxillary second premolar models were restored with one of the four following RBFPD designs (n=10): I) A premolar occlusal bar combined with molar double rests (MDR); II) both occlusal bars with a wing (OBB); III) a premolar occlusal bar combined with a molar dental band (MDB); and IV) two single rests adjacent to the edentulous space with a wing (SRB) used as a control. All specimens were aged with thermal cycling and mechanical loading. Subsequently, they were loaded until broken. The data were analyzed by one-way analysis of variance. Al₂O₃ (250 µm) abrasion provided the highest SBS (P<0.05). The alloy primer and silica + silane exhibited increased SBS. Furthermore, fracture analysis revealed that the failure mode varied among the different treatments. Whereas MDB exhibited the highest retention (P<0.05), that of OBB was greater than that of MDR (P<0.05), and the control exhibited the lowest retention. Abrasion with Al₂O₃ (250 µm) effectively increased the adhesive property of Pd-Ag. Additionally, treatment with the alloy primer and silica coating + silane was able to increase the adhesive property of abraded Pd-Ag. Under the present conditions, all three modified retainer types provided improved outcomes for Pd-Ag PFM RBFPDs compared with the control.

Effect of thione primers on adhesive bonding between an indirect composite material and Ag-Pd-Cu-Au alloy

The current study evaluated the effect of primers on the shear bond strength of an indirect composite material joined to a silverpalladium-copper-gold (Ag-Pd-Cu-Au) alloy (Castwell). Disk specimens were cast from the alloy and were air-abraded with alumina. Eight metal primers were applied to the alloy surface. A light-polymerized indirect composite material (Solidex) was bonded to the alloy. Shear bond strength was determined both before and after the application of thermocycling. Two groups primed with Metaltite (thione) and M. L. Primer (sulfide) showed the greatest post-thermocycling bond strength (8.8 and 6.5 MPa). The results of the X-ray photoelectron spectroscopic (XPS) analysis suggested that the thione monomer (MTU-6) in the Metaltite primer was strongly adsorbed onto the Ag-Pd-Cu-Au alloy surface even after repeated cleaning with acetone. The application of either the thione (MTU-6) or sulfide primer is effective for enhancing the bonding between a composite material and Ag-Pd-Cu-Au alloy.

Effect of a self-etching primer and phosphoric acid etching on the bond strength of 4-META/MMA-TBB resin to human enamel

The purpose of this study was to evaluate the shear bond strength and durability of 4-META/MMA-TBB resin to human enamel. A self-etching primer that contained 4-META (Teeth Primer, TP) and 35-45% or 60-65% concentrations of phosphoric acid (K-Etchant Gel, KE, and Super Bond C&B Red Activator, RA) were used as the surface treatment agents. A methyl methacrylate (MMA)-based self-polymerizing resin (Super-Bond C&B) was used as a luting agent. The shear bond strength was determined both pre and post thermocycling. The results were statistically analyzed with a non-parametric procedure. The post-thermocycling shear bond strength of the TP group was significantly higher than that of other groups, and that of the KE group was significantly higher compared with the RA group. These results demonstrated that 4-META was effective. Furthermore, when the degree of tooth demineralization was compared, surface treatment with less demineralization using TP was the most effective treatment.