Applied Adhesion Science最新文献

This study evaluated the effect of different ceramic primers and heat treatment of silane coupling agents on bond strength of resin cement to glass ceramic. Five ceramic primers (Clearfil Ceramic Primer/CCP, MonoBond-S, ProSil, RelyX Ceramic Primer and Silano) and one conventional resin cement (RelyX ARC) were tested. Lithium disilicate-based ceramic plates were previously etched with hydrofluoric acid, except for CCP (n?=?10). All silane agents were applied to ceramics according to the manufacturer’s instructions and primed ceramics plates were heated (in oven at 100?°C for 1?min) or not before resin cement placement. Dual-cure resin cement was mixed and inserted in tubes (0.75?mm diameter?×?1?mm height) that were positioned over primed ceramic surfaces. Micro-shear testing was performed using a universal testing machine. Bond strength data were analyzed using two-way ANOVA and Tukey’s test (5%). Ceramic primer heating did not improve the bond strength of the resin cement to lithium disilicate. Most of ceramic primers did not indicate significant difference in bond strength among them; however, CCP yielded the lowest bond strength among the ceramic primers. In conclusion, when the silane was applied on etched surface the bond strength was higher and heat treatment of silane coupling agents did not affect the bond strength.

This study investigated the effect of adding different concentrations of phosphate-grafted-silica nanoparticles (SiO₂–POOH) on dentin bond strength of experimental one-step self-etching adhesives (1-SEAs). Phosphate functional group was grafted onto silica nanoparticles through the free radical polymerization of an acid phosphate monomer [methacryloyloxyethyl dihydrogen phosphate/bis (methacryloyloxyethyl) hydrogen phosphate—HEMA-P] in an alcoholic medium. The resulting SiO₂–POOH was characterized by FTIR spectroscopy. 1-SEA with two different acidic phosphate monomer concentrations (HEMA-P at 0 and 40%?wt) were prepared and SiO₂–POOH was added in 0 (control), 0.1, 0.2, 0.5, 1, 2, 4, 6 and 8wt%. The formulated 1-SEAs were evaluated for shear bond strength to dentin. Statistical comparisons were conducted at 5% significance level. The grafting reaction of SiO₂–POOH was confirmed by FTIR. Compared with the unfilled 1-SEA, the addition of 0.1wt% of SiO₂–POOH nanoparticles resulted in a significant dentin bond strength increase for HEMA-P_40% concentration (p?≤?0.001) while the addition of higher concentration of SiO₂–POOH (0.2, 0.5, 1, 2, 4, 6 and 8wt%) reduced significantly the bond strength. The 1-SEA formulated without an acidic monomer (HEMA-P_0%) did not exhibit bonding to the dentin, irrespective of SiO₂–POOH concentration added. SiO₂–POOH nanoparticles were obtained through graft polymerization of acidic phosphate monomer with silanized SiO₂ nanoparticles. The addition of the 0.1wt% of SiO₂–POOH nanoparticles associated with acidic monomer to 1-SEA improves the bonding effectiveness.

An epoxy monolith layer with porous structure is fabricated on the surface of a stainless steel (SUS) plate by polymerization induced phase separation process as the mediator for the bonding of SUS and various thermoplastic resin plates. Bonding strength is evaluated in the presence and absence of the epoxy monolith layer by a tensile lap shear test. The morphology of fracture surfaces is observed by scanning electron microscopy (SEM) in order to clarify the anchor effect of molten resins into the pores of the epoxy monoliths. The bonding strength values are calculated to be 1.2?2.7?MPa based on an apparent adhesion area for the bonding of SUS with polyethylene, polypropylene, polyoxymethylene and acrylonitrile–butadiene–styrene copolymer in the presence of the epoxy monolith mediator. These values are 2?30 times higher than those for direct metal-resin bonding. By the SEM observation, stretched needle-like structures were detected on the both fracture surfaces of the resins and the epoxy monoliths. The direct observation of the stretched debris out of the holes located at the monolith surfaces indicates the significant anchor effect for the present metal-resin bonding system. The bonding system mediated by the epoxy monolith layer is conveniently used for the bonding of dissimilar materials such as metals and resins without any special process and apparatus.

The aim of this study was evaluate the influence of the substance used as root canal lubricant during relining and the cleaning protocol on the bond strength of relined posts to root dentin. Eighty single canal mandibular bovine incisors were used in the study. The root canals were endodontically treated and allocated into four groups (n?=?20) according to the lubricant material and the root canal cleaning protocol: petroleum jelly/no cleaning; petroleum jelly/cleaning with paper points; hydrosoluble gel/no cleaning; hydrosoluble gel/water rinse and drying with paper points. All posts were relined with resin composite and luted to the root canals with regular resin cement. Specimens were cross-sectioned to obtain root slices producing 1.5?mm thick slices. The push-out test was performed at a crosshead speed of 0.5?mm/min until post dislodgement occurred. The failure mode was verified using a stereomicroscope. Data were analyzed by two-way ANOVA followed by Tukey post hoc test (push-out) with α?=?0.05. A statistically significant difference was found considering the type of lubricant (p?<?0.001). The hydrosoluble gel/water rinse group showed the highest mean bond strength value (11.0?±?3.7?MPa). The most frequent pattern of failure was adhesive between the root canal walls and resin cement. The use of a hydrosoluble gel as lubricant substance seems to be adequate for the relining post technique.

This study compared the microtensile bond strength (BS) and the micromorphology of resin-dentin interface (MI) of a conventional adhesive to two-steps etch-and-rinse bonding agents after 1?year of water storage. Twenty-eight human third molars were used (n?=?7). Teeth were divided into four groups (GCB: Gluma Comfort Bond; OPB: OptiBond FL; OCB: One Coat Bond SL; PUB: Peak Universal Bond). Specimens were tested in tension after 24?h or 1?year of water storage. Dentin BS strength data were analyzed by split-plot two-way ANOVA followed by Tukey–Kramer tests (α?=?0.05). Water-storage for 1?year significantly decreased BS for OCB; however, no significant difference was noted between OCB and GCB and PUB adhesives after 1?year of water-storage. OPB showed the highest BS values at both storage times. All adhesives formed a hybrid layer with resin tags, and both interfacial structures were maintained after 1?year. However, degradation signals within interfacial structures were observed only for the adhesive with a bond strength reduction. BS test showed that only one adhesive declined after 1?year of water storage. The degradation of some structures of the interface collaborated this finding. The classic three-step etch-and-rinse (OPB) presented higher values of bond strength than GCB and OCB after 1?year, but it was not statistically different from PUB.

The interference of eugenol on the adhesive systems and composite polymerization could promote a higher marginal microleakage. This could be reduced by mechanical and chemical cleansing. The objective of this study was to evaluate the influence of the previous use of eugenol-based materials to a permanent restoration on the marginal microleakage. The influence of mechanical cleansing associated with chemical cleansing with chlorhexidine gel was also evaluated. Non-eugenol endodontic sealer and temporary material and mechanical cleansing was used as a control. Eighty bovine incisors were endodontic treated and divided into eight groups (n?=?10) according to the sealer, temporary material and removal method. The specimens were temporarily restored and stored for 1?week at 37?°C and 100?% relative humidity, followed by definitive restoration and one-year storage at the same environment. The teeth were then sealed, immersed in silver nitrate at 50?% for 2?h and sectioned to have the microleakage qualitatively and quantitatively visually analyzed under a stereomicroscope at 45×. The percentage data were submitted to an ANOVA and Tukey’s test, and the scores were submitted to a Kruskal–Wallis and Dunn’s test at 5?% of the significance level. There was no difference between the groups when mechanical removal was made (p?>?0.05). When chlorhexidine was used, the group that used endodontic eugenol based material as a sealer and the resin-based material as a temporary restoration showed less microleakage than the other (p?<?0.05). All groups showed less microleakage when chlorhexidine was used instead of solely using mechanical removal (p?<?0.05). For scores, when the eugenol based sealer was combined with resin-based temporary material, and when the resin sealer was combined with eugenol based temporary material using chlorhexidine, a lower median was found (p?<?0.05) compared to all other groups. Eugenol showed no influence, and chlorhexidine gel showed to be effective in reducing microleakage.

Adhesives used to bond the wood panels are petroleum-based and has volatile organic compound, VOCs. Harmful substance when inhaled by human being and can cause different problems, such as cancer. As an alternative to replace these adhesives is to use the polyurethane derived from castor oil (PU), a renewable resource that can be used to structural applications, indoor and outdoor environments. It is weather resistant and has good mechanics properties. The aim of this paper is to evaluate the mechanical resistance of glued joint with PU biding MDF panels. It was produced raw MDF samples glued two by two with 0.05?g of adhesive in 1?cm². Where 6 samples were used with PVA adhesive, 6 with contact adhesive and 6 with PU. After 72?h it was applied a mechanical analysis technique of shear bond strength, according to the standards ASTM D 3983-93 and ASTM D897-95A. The results shows the shear average resistance of PU was 12.67?±?2.26?MPa, whereas for the PVA adhesive was 2.55?±?0.19?MPa and the contact adhesive was 3.26?±?0.63?MPa. It is conclusive the polyurethane derived from castor oil can be used to bind MDF panels, due to its superior shear average resistance compared to PVA and contact adhesives.

This study, we evaluated the effect of green tea on the shear bond strength of metal orthodontic brackets to human enamel after home whitening treatment. Ninety premolars were selected and divided into six experimental groups: G1, no treatment (positive control); G2, whitening (negative control); G3, no whitening?+?10?% sodium ascorbate (SA) gel; G4, no whitening?+?10?% green tea (GT) gel; G5, whitening?+?SA; and G6, whitening?+?GT. The samples of G2, G5, and G6 were whitened with 10?% carbamide peroxide for 8?h daily, during 14?days at 37?°C. G3, G4, G5, and G6 were treated with the respective antioxidants (GT or SA) for 1?h at 37?°C. After the treatments, the brackets were bonded with Transbond XT. Then, the samples were tested in a universal testing machine and the adhesive remnant index (ARI) was examined under 40× magnification. Data were submitted to analysis of variance, Tukey’s and Dunnett’s tests (α?=?5?%). The averages (standard deviations) obtained were: G1, 17.6 (4.1); G2, 9.8 (3.6); G3, 18.1 (4.1); G4, 18.2 (4.7); G5, 14.9 (2.5); and G6, 14.8 (5.4). G2 had statistically lower values than the other groups. Concerning the ARI, all groups had a higher number of flaws type score 0 (no material adhered to the tooth). We conclude that the use of GT can be an alternative method to allow bracket bonding immediately after home whitening treatment.