Durability Of Resin Research Articles

On the fatigue behavior of resin–dentin bonds after degradation by biofilm

The durability of resin–dentin bonds is a growing concern in the placement of composite restorations. Most reported evaluations concerning the mechanical behavior of the bonded interface are conducted using static loading to failure only. They also do not account for the acid production of biofilms, which is one of the most common contributors to interfacial failures in vivo. In this investigation resin–dentin bonded interface specimens were exposed to S. mutans for 14 days and then subjected to quasi-static or cyclic four-point flexure to failure. Control specimens (without biofilm) were evaluated after aging for one and fourteen days. While no significant difference in flexure strength resulted from the duration of water aging (66.2MPa vs. 56.9MPa), biofilm exposure caused a significant reduction in strength (29.3MPa; p≤0.000). After water aging for one and fourteen days the apparent endurance limits were 13.0MPa and 13.1MPa, respectively. Biofilm treatment caused a significant (p≤0.001) reduction in fatigue resistance of the interface, and the endurance limit was reduced to 9.9MPa. Fatigue failure of the control specimens initiated within the resin composite adjacent to the interface, whereas failure of the biofilm treated specimens initiated within the hybrid layer and appeared attributed to the localized demineralization of dentin. Biofilm degradation is an important consideration in assessing the durability of resin–dentin bonds.

Development of Resin Disc Soil Testing in Rice Crop in Relation to Kinetics of Nutrient Adsorption on Resin

The aim of this investigation was to develop a durable, rigid, and reusable resin disc for soil testing with the hypothesis that a uniformly shaped disc of cation/anion exchange resin placed in direct contact with the soil will accumulate ions from the soil by processes similar to those for living plant roots in the natural soil–solution–plant continuum. To develop regression equations for the relationship of resin-adsorbed quantity (RAQ) to yield of rice, soils were collected before sowing from different plots of a rice field where a fertility gradient had been created in the previous year by growing rice with different doses of fertilizers. For resin-disc soil testing, a soil sample is made into a saturated paste and placed in intimate contact with the resin disc. After 24 h (as decided from the kinetic experiment), the resin disc–soil assembly was dismantled. Ammonium, phosphate, sulfate, and potassium ions were extracted from the discs. Rice was grown in those plots without any fertilizer, and yields were recorded. Regression analysis was done between yield and nutrients adsorbed by the resin (NAR). The same soils were also analyzed for organic carbon, phosphate, sulfate, and potassium by the conventional chemical extraction method. Multiple regression analyses of grain yield (Y) as the dependent variable and resin-adsorbed N (RN), resin-adsorbed P (RP), resin-adsorbed K (RK), and resin-adsorbed S (RS) as independent variables produced the following relationships: Y = 5.95 + 5.13RN + 23.85RP – 2.4RK + 1.05RS, multiple R2 = 0.793. The resin-disc method gave much better regression with rice yield than the conventional chemical extraction method.

Epigallocatechin-3-gallate (EGCG) enhances the therapeutic activity of a dental adhesive

ObjectivesThe purpose of this study was to evaluate the antibacterial potential and physicochemical properties of a dental adhesive incorporated with epigallocatechin-3-gallate (EGCG) in different concentration over time. MethodsEGCG was incorporated at a ratio of 100, 200, and 300μg/ml into a dental adhesive. The effects of the cured adhesives on the growth of Streptococcus mutans were determined by direct contact test immediately or one month later and by scanning electron microscopy (SEM), respectively. Microtensile bond strength (μTBS) test was used to test the mechanical property of the adhesives immediately or six months later. The degree of conversion (DC) of the adhesives was evaluated by Fourier Transform Infrared Spectroscopy (FTIR). ResultsCompared with negative control, the 200μg/ml and 300μg/ml EGCG-incorporated dental adhesive were found to exhibit inhibitory effect on the growth of S. mutans. The μTBS of the EGCG-incorporated dental adhesive was higher than the control. The DC of the adhesive system was not affected by the addition of EGCG. Conclusions200μg/ml EGCG incorporated dental adhesives could accomplish therapeutic goals that play in antimicrobial function whilst keeping the durability of resin–dentine bond.

Synthesis, Characterization, and Applications of a New Ion Exchanger Tamarind 4-aminobenzoic Acid (TABA) Resin in Industrial Wastewater Treatment

Chromatographic column separations of toxic metal ions from industrial wastewater were achieved in acid media at optimized (Kd) values with a synthesized cation exchange TABA resin. The prepared TABA resin was characterized by FTIR, elemental, and thermogravimetric analysis. Studies of total ion exchange capacity, resin durability, and swelling were carried out. The distribution coefficient values of metal ions, viz Cu2+, Fe2+, Zn2+, Cd2+ and Pb2+ at different pH, were also studied using a batch equilibration method. The different factors affecting metal ions adsorption on this substrate, such as treatment time, agitation speed, and temperature, were studied in detail.

Durability of Resin Cement Bond to Aluminium Oxide and Zirconia Ceramics after Air Abrasion and Laser Treatment

The erbium laser has been introduced for cutting enamel and dentin and may have an application in the surface modification of high-strength aluminum oxide and zirconia ceramics. The aim of this study was to evaluate the durability of the bond of conventional dual-cured resin cements to Procera Al(2)O(3) and zirconium oxide ceramics after surface treatment with air abrasion and erbium laser. One hundred twenty Al(2)O(3) and 120 zirconia specimens measuring 3 × 3 × 0.7 mm(3) were divided equally into three groups, and their surfaces treated as follows: either untreated (controls), air abraded with Al(2)O(3) particles, or erbium-laser-treated at a power setting of 200 mJ. The surface of each specimen was then primed and bonded with one of two dual-cured resin cements (either SCP-100 Ceramic Primer and NAC-100 or Monobond S and Variolink II) using a 1-mm thick Tygon tube mold with a 0.75-mm internal bore diameter. After 24 hours and 6 months of water storage at 37°C, a microshear bond strength test was performed at a crosshead speed of 1 mm/min. Surface morphology was examined using a confocal microscope, and failure modes were observed using an optical microscope. The data were analyzed using the Kaplan-Meier nonparametric survival analysis. In the case of zirconia, air abrasion and Erbium:yttrium-aluminum-garnet (Er:YAG) laser treatment of the ceramic surface resulted in a significant reduction in the bond strengths of both resin cements after 6 months water storage; however, when the zirconia surface was left untreated, the SCP-100/NAC-100 group did not significantly reduce in bond strength. In the case of alumina, no treatment, air abrasion and Er:YAG laser treatment of the surface led to no significant reduction in the bond strengths of the three SCP-100/NAC-100 groups after 6 months water storage, whereas all three Monobond S/Variolink II groups showed a significant reduction. Er:YAG laser treatment of the zirconia surface did not result in a durable resin cement/ceramic bond; however, a durable bond between a conventional dual-cured resin cement and Procera All Ceram and Procera All Zirkon was formed using a ceramic primer containing the phosphate monomer, MDP, without any additional surface treatment.

State of the art etch-and-rinse adhesives

Objectives: The aim of this study was to explore the therapeutic opportunities of each step of 3-step etch-and-rinse adhesives. Methods: Etch-and-rinse adhesive systems are the oldest of the multi-generation evolution of resin bonding systems. In the 3-step version, they involve acid-etching, priming and application of a separate adhesive. Each step can accomplish multiple goals. Acid-etching, using 32–37% phosphoric acid (pH 0.1–0.4) not only simultaneously etches enamel and dentin, but the low pH kills many residual bacteria. Results: Some etchants include anti-microbial compounds such as benzalkonium chloride that also inhibits matrix metalloproteinases (MMPs) in dentin. Primers are usually water and HEMA-rich solutions that ensure complete expansion of the collagen fibril meshwork and wet the collagen with hydrophilic monomers. However, water alone can re-expand dried dentin and can also serve as a vehicle for protease inhibitors or protein cross-linking agents that may increase the durability of resin–dentin bonds. In the future, ethanol or other water-free solvents may serve as dehydrating primers that may also contain antibacterial quaternary ammonium methacrylates to inhibit dentin MMPs and increase the durability of resin–dentin bonds. The complete evaporation of solvents is nearly impossible. Significance: Manufacturers may need to optimize solvent concentrations. Solvent-free adhesives can seal resin–dentin interfaces with hydrophobic resins that may also contain fluoride and antimicrobial compounds. Etch-and-rinse adhesives produce higher resin–dentin bonds that are more durable than most 1 and 2-step adhesives. Incorporation of protease inhibitors in etchants and/or cross-linking agents in primers may increase the durability of resin–dentin bonds. The therapeutic potential of etch-and-rinse adhesives has yet to be fully exploited.

A 2-year in vitro evaluation of a chlorhexidine-containing acid on the durability of resin–dentin interfaces

Objective This study evaluated the effect of 2% chlorhexidine-containing acid (Ac/CHX) and 2% chlorhexidine digluconate solution (CHX) on immediate (IM) and 2-year (2Y) resin–dentin bond strength (BS) and silver nitrate uptake (SNU) for two simplified etch-and-rinse adhesives. Methods Forty-two caries-free extracted molars had a flat dentin surface exposed. In the control groups (groups 1), the surfaces were acid etched with conventional phosphoric acid and the adhesives Prime&Bond NT (PB) or Adper Single Bond 2 (SB) was applied after rinsing, drying and rewetting with water. In groups 2, Ac/CHX groups the adhesives were applied in a similar manner; however a 2% CHX-containing acid was previously applied. In groups 3, the adhesives were applied according to the control group; however the rewetting procedure was performed with an aqueous solution of 2% CHX for 60 s. Composite build-ups were constructed incrementally and microtensile specimens (0.8 mm 2) were prepared for microtensile bond strength testing in the IM or 2Y periods at 0.5 mm/min. For SNU, 2 bonded sticks from each tooth were coated with nail varnish, placed in the silver nitrate, polished down with SiC papers and analysed by EDX-SEM. The data from each adhesive was submitted to a two-way repeated measures ANOVA and Tukey's test ( α = 0.05). Results After 2Y, significant reductions of BS were observed for both adhesives in the control group ( p < 0.05). In Ac/CHX or CHX groups the BS remained stable for both systems. SNU was more evident in the control than in the experimental groups ( p < 0.05) both in IM and 2Y periods. The use of CHX in an aqueous solution or associated with the acid conditioner was effective to reduce the degradation of dentin bonds over a 2-year period. Significance The addition of CHX digluconate in the acidic conditioner may be an excellent tool to increase the long-term stability of collagens fibrils within the hybrid layer against host-derived metalloproteinases without the need for additional steps for the bonding protocol.

Chemical adhesion rather than mechanical retention enhances resin bond durability of a dental glass-ceramic with leucite crystallites

This study aims to evaluate the effect of chemical adhesion by a silane coupler and mechanical retention by hydrofluoric acid (HFA) etching on the bond durability of resin to a dental glass ceramic with leucite crystallites. Half of the ceramic plates were etched with 4.8% HFA (HFA group) for 60 s, and the other half were not treated (NoHFA group). The scale of their surface roughness and rough area was measured by a 3D laser scanning microscope. These plates then received one of the following two bond procedures to form four bond test groups: HFA/cement, NoHFA/cement, HFA/silane/cement and NoHFA/silane/cement. The associated micro-shear bond strength and bond failure modes were tested after 0 and 30 000 thermal water bath cycles. Four different silane/cement systems (Monobond S/Variolink II, GC Ceramic Primer/Linkmax HV, Clearfil Ceramic Primer/Clearfil Esthetic Cement and Porcelain Liner M/SuperBond C&B) were used. The data for each silane/cement system were analyzed by three-way ANOVA. HFA treatment significantly increased the surface Ra and Ry values and the rough area of the ceramic plates compared with NoHFA treatment. After 30 000 thermal water bath cycles, the bond strength of all the test groups except the HFA/Linkmax HV group was significantly reduced, while the HFA/Linkmax HV group showed only adhesive interface failure. The other HFA/cement groups and all NoHFA/cement groups lost bond strength completely, and all NoHFA/silane/cement groups with chemical adhesion had significantly higher bond strength and more ceramic cohesive failures than the respective HFA/cement groups with mechanical retention. The result of the HFA/silane/cement groups with both chemical adhesion and mechanical retention revealed that HFA treatment could enhance the bond durability of resin/silanized glass ceramics, which might result from the increase of the chemical adhesion area on the ceramic rough surface and subsequently reduced degradation speed of the silane coupler, rather than the mechanical retention of the ceramic rough surface.

Substantivity of chlorhexidine to human dentin

Objectives To better comprehend the role of CHX in the preservation of resin–dentin bonds, this study investigated the substantivity of CHX to human dentin. Material and methods Dentin disks ( n = 45) were obtained from the mid-coronal portion of human third molars. One-third of dentin disks were kept mineralized (MD), while the other two-thirds had one of the surfaces partially demineralized with 37% phosphoric acid for 15 s (PDD) or they were totally demineralized with 10% phosphoric acid (TDD). Disks of hydroxyapatite (HA) were also prepared. Specimens were treated with: (1) 10 μL of distilled water (controls), (2) 10 μL of 0.2% chlorhexidine diacetate (0.2% CHX) or (3) 10 μL of 2% chlorhexidine diacetate (2% CHX). Then, they were incubated in 1 mL of PBS (pH 7.4, 37 °C). Substantivity was evaluated as a function of the CHX-applied dose after: 0.5 h, 1 h, 3 h, 6 h, 24 h, 168 h (1 week), 672 h (4 weeks) and 1344 h (8 weeks) of incubation. CHX concentration in eluates was spectrophotometrically analyzed at 260 nm. Results Significant amounts of CHX remained retained in dentin substrates (MD, PPD or TDD), independent on the CHX-applied dose or time of incubation ( p < 0.05). High amounts of retained CHX onto HA were observed only for specimens treated with the highest concentration of CHX (2%) ( p < 0.05). Conclusion The outstanding substantivity of CHX to dentin and its reported effect on the inhibition of dentinal proteases may explain why CHX can prolong the durability of resin–dentin bonds.

The effect of zirconia surface treatment on flexural strength and shear bond strength to a resin cement

Despite the expanded applications for zirconia in restorative dentistry, there is no clear recommendation in the literature regarding surface treatment before bonding. The purpose of this study was to evaluate the effect of mechanical surface treatment of yttria-partially stabilized zirconia on its flexural strength and the effect of mechanical and chemical surface treatments on its bond strength to a resin cement. For flexural strength evaluation, zirconia bars (4 x 5 x 40 mm) were prepared from zirconia blocks, finished using a diamond rotary cutting instrument, sintered, then assigned into 4 groups: (1) control (no treatment), (2) airborne-particle abrasion, (3) silicoating, and (4) wet hand grinding. After storage for 24 hours at 37 degrees C, flexural strength was determined using a 3-point bending test, and the results were analyzed using 1-way ANOVA (alpha=.05). For shear bond strength evaluation, zirconia rods (2.5 x 3 mm) were prepared from zirconia blocks, sintered, and assigned into 16 groups. Each group underwent a combination of the following mechanical and chemical treatments. Mechanical treatment included: (1) control (no treatment), (2) airborne-particle abrasion, (3) silicoating, or (4) wet hand grinding. Chemical treatment included: (1) control (no treatment), (2) acid etching followed by silanation, (3) silanation only, or (4) application of zirconia primer. Dentin specimens were prepared from extracted molars stored in 0.5% chloramine-T. Zirconia rods were bonded to dentin using a resin cement (Multilink Automix), then light polymerized. After storage, the specimens were loaded to failure with the notched shear bond test method in a universal loading apparatus. For artificial aging analysis, the groups that achieved the highest bond strength values were duplicated, stored at 37 degrees C and 100% humidity for 90 days, and thermal cycled before being loaded to failure. Results were analyzed using 2-way ANOVA (alpha=.05). Airborne-particle abrasion and hand grinding significantly increased flexural strength. The highest shear bond strength values were achieved for the following groups: silicoated + silanated > hand ground + zirconia primer > airborne-particle abraded + silanated > zirconia primer > airborne-particle abraded + zirconia primer. Artificial aging resulted in significantly lower shear bond strength for the silicoated/silanated and the zirconia primer groups. Mechanical modification of the surface increased the flexural strength of Y-TZP. The resin bond to Y-TZP was improved by surface treatment. A combination of mechanical and chemical conditioning of the zirconia surface was essential to develop a durable resin bond to zirconia.

Automated determination of uranium(VI) at ultra trace levels exploiting flow techniques and spectrophotometric detection using a liquid waveguide capillary cell

Rapid and fully automated multisyringe flow-injection analysis (MSFIA) with a multi-pumping flow system (MPFS) coupled to a long path-length liquid waveguide capillary cell (LWCC) is proposed for the determination of uranium(VI) at ultra trace levels. On-line separation and pre-concentration of uranium is carried out by means of a TRU resin. After elution, uranium(VI) is spectrophotometrically detected after reaction with arsenazo-III. Combination of the MSFIA and MPFS techniques with the TRU-resin enables the analysis to be performed in a short time, using large sample volumes and achieving high selectivity and sensitivity levels. A detection limit of 12.6 ng L(-1) (ppt) is reached for a 100-mL sample volume. The versatility of the proposed method also enables pre-concentration of variable sample volumes, enabling application of the analysis to a wide concentration range. Reproducibility of better than 5% and a resin durability of 40 injections should be emphasized. The developed method was successfully applied to different types of environmental sample matrices with recoveries between 95 and 108%.

Effect of concentration of chlorhexidine on bonding durability of dentine and resin

To evaluate the effect of concentration of chlorhexidine on bonding durability of dentine and resin. Forty extracted third molars were randomly allocated into five groups, which include one control group and four test groups. Teeth dentin surfaces in each group were treated with one of the following solution, 1.5 microl water (control), 0.02%, 0.2%, 2% and 20% chlorhexidine. Single Bond 2 adhesive was applied to the dentin surface according to manufacturer's recommendations. Then 5 mm thickness of composite (Z250) was built up on the dentin of each molar. The teeth were sectioned into microtensile samples and subdivided into two subgroups, 16 samples each. Samples in subgroup II and I were tested after being stored in distilled water for 24 h and 6 month respectively. Each fractured sample was examined with SEM. No significant differences of 24 h bonding strength were found among the five groups. There were significant difference in bonding strength between 0.2%, 2% chlorhexidine groups [(24.68 ± 5.26) and (23.19 ± 5.26) MPa] and the control group [(19.10 ± 4.67) MPa] after 6 month (P = 0.007,0.045), and significant differences were also found between 0.2%, 2% and 0.02% chlorhexidine group [(19.01 ± 6.87) MPa, P = 0.006, 0.041). Most of the fractured modes were mixed or interface failures after 24 h of water storage, and the mixed failure increased after six month of water storage. In the 0.2%, 2% and 20% chlorhexidine treated group, most of the failure was found at the top of hybrid layer, while in the 0.02% group, it was found in the base part of hybrid layer. Chlorhexidine could increase the bonding durability of resin and dentine. Higher than 0.2%, concentration of chlorhexidine couldn't improve bonding durability.

Development of a ceramic primer with higher bond durability for resin cement

To increase the bond durability of resin to the CAD/CAM ceramic surface, two types of two-bottle type ceramic primers, consisting of Primer A1 or A2 and Primer B, were designed. Primer A1 was prepared by dissolving 25, 50, or 100 mg of gamma-methacryloxypropyltrimethoxysilane in 1 mL of ethanol. Primer A2 was prepared by dissolving 50 mg of mixed silanes, consisting of 1,2-bis(trimethoxysilyl)ethane to gamma-methacryloxypropyltrimethoxysilane, in 1 mL of ethanol. Mole fractions of 1,2-bis(trimethoxysilyl)ethane to gamma-methacryloxypropyltrimethoxysilane were 0, 10, 20, 30, 40 and 50 mol%. Primer B was prepared after dissolving 0.01, 0.05 or 0.1 mol L(-1) hydrochloric acid in ethanol by 50 vol%. Ceramic surface was silanated with a mixture of Primers A1 and B or Primers A2 and B for 1 min, and then air-dried. Commercial GC ceramic primer and Porcelain Liner M were utilized. Thereafter, dual-curing type resin cement was bonded to silanated ceramic surface through visible-light irradiation. Shear bond strength of resin to the ceramic surface was measured, before and after thermo-cycling. Addition of 0.01 or 0.05 mol L(-1) hydrochloric acid to the gamma-methacryloxypropyltrimethoxysilane allowed for significant increases in the bond strength. However, thermo-cycling resulted in significant decreases of approximately 5 MPa in the bond strength. Conversely, when the mixed silane, where 30 mol% of 1,2-bis(trimethoxysilyl)ethane dissolved in gamma-methacryloxypropyltrimethoxysilane, was utilized with 0.05 mol L(-1) hydrochloric acid, the reduction in the bond strength decreased to approximately 2 MPa. The designed ceramic primers exhibited higher ceramic bond durability than commercial ceramic primers.

Durability of resin–dentin bonds using the ethanol bonding technique

Durability of resin–dentin bonds using the ethanol bonding technique

Durability of resin bonding to zirconia ceramic using different primers.

The purpose of this in vitro study was the evaluation of the bond strength and its durability to zirconia ceramic after using two phosphate monomer-containing primers. Plexiglas tubes filled with composite resin were bonded to zirconia ceramic disks (Cercon) which were air abraded (50 microm Al2O3 at 2.5 bar pressure) and ultrasonically cleaned in isopropanol for 3 min. Groups of 16 specimens each were bonded with Multilink Automix using either no primer (NO) or using a metal primer (AP: Alloy Primer, Kuraray) or a metal and zirconia primer (MZ: Metal/Zirconia Primer, Ivoclar Vivadent). Another group bonded with a phosphate monomer (MDP) containing resin (PF: Panavia F, Kuraray) served as control for an established bonding method to zirconia ceramic. Prior to tensile bond strength testing, subgroups of 8 bonded specimens were stored in distilled water (37 degrees C) for either 3 or 150 days. Additionally, the 150-day specimens were thermocycled (TC) between 5 degrees and 55 degrees 37,500 times. Statistical analyses were conducted with the Wilcoxon rank sum test. Without primer, the median initial bond strength of Multilink Automix to zirconia ceramic was relatively low (12.4 MPa). The primers improved the bond strength significantly (p <or= 0.05), increasing them to 38.5 MPa (Metal/Zirconia Primer) and 53.6 MPa (Alloy Primer). The Alloy Primer group did not differ significantly from the control group Panavia F with 51.8 MPa. After 150 days storage and TC, specimens without primer (NO) debonded spontaneously, while the other groups showed significantly reduced bond strengths ranging from 19.7 to 37.2 MPa. Using phosphate monomer-containing primers on air-abraded zirconia ceramic improves bonding to zirconia ceramic significantly.

Dentin as a bonding substrate

Dentin comprises the largest dental structure available for bonding. Because of its inherent morphological and physiological characteristics, reliable and durable resin–dentin bonding remains a challenging accomplishment that is subjected to multi‐factorial interferences. Adhesive technology has evolved significantly over the past decade, resulting in improved predictability of resin–dentin bonds. This article reviews the present knowledge regarding resin–dentin bonding from the perspective of the dentin substrate. Since another article in the previous issue ofEndodonticTopicsalready covers dentin structure and composition, the intention is not to fully review these aspects. Instead, basic principles of current bonding strategies used by adhesive agents are presented. Specific attention is given to describing how the morphology and physiology of dentin affect existing bonding mechanisms, how some chemical treatments of dentin can affect its properties and bonding, and finally how bonding to root canal dentin is currently viewed and understood.

EDTA or H 3PO 4/NaOCl dentine treatments may increase hybrid layers’ resistance to degradation: A microtensile bond strength and confocal-micropermeability study

Objectives The aim of this study was to reduce hybrid layer degradation created with simplified dentine adhesives by using two different methods to condition the dentine surface. Methods A smear-layer was created on flat dentine surfaces from extracted human third molars with a 180-grit/SiC-paper. Dentine specimens were conditioned before bonding with the following procedures: 37% H 3PO 4; H 3PO 4/0.5% NaOCl; 0.1 M EDTA; 0.1 M EDTA/0.5% NaOCl. Two etch-and-rinse adhesives: (Scotchbond 1XT or Optibond Solo Plus) were applied and light-cured. Composite build-ups were constructed. The bonded teeth were sectioned into beams, stored in distilled water (24 h) or 12% NaOCl solution (90 min) and finally tested for microtensile bond strengths (μTBS). Additional dentine surfaces were conditioned and bonded as previously described. They were prepared for a pulpal-micropermeability confocal microscopy study and finally observed using confocal microscopy. Results μTBS results revealed that both adhesives gave high bond strengths to acid-etched dentine before, but not after a 12% NaOCl challenge. Bonds made to acid-etched or EDTA-treated dentine plus dilute NaOCl, gave high μTBS that resisted 12% NaOCl treatment, as did EDTA-treated dentine alone. A confocal micropermeability investigation showed very high micropermeability within interfaces of the H 3PO 4, etched specimens. The lowest micropermeability was observed in H 3PO 4 + 0.5% NaOCl and 0.1 M EDTA groups. Conclusions The use of dilute NaOCl (0.5%) after acid-etching, or the conditioning of dentine smear layers with 0.1 M EDTA (pH 7.4) produced less porous resin–dentine interfaces. These dentine-conditioning procedures improve the resistance of the resin–dentine bond sites to chemical degradation (12% NaOCl) and may result in more durable resin–dentine bonds.

Thermocycling Effects on Resin Bond to Silicatized and Silanized Zirconia

Various techniques have been introduced to create a durable resin composite bond to sintered zirconia (Y-TZP). Shear bond strength values achieved through tribochemical treatment have been investigated in numerous studies, but less is reported about long-term durability. The objective here was to evaluate the effects of thermocycling and silane on shear bond strength of a composite luting cement to silicatized Y-TZP. Two groups of Y-TZP (Procera Zirconia, Nobel Biocare), both consisting of 40 specimens were prepared. The specimen surfaces were air particle abraded with silica-coated aluminum trioxide particles (particle size 110 μm, duration 15 s, air pressure 300 kPa, nozzle distance 10 mm). The silica-coated surfaces in group ZA were silanized with an acrylate-functional silane (Experimental laboratory-made acrylate silane, Toray Dow Corning Silicone) and in the other group ZM with a pre-activated methacrylate silane (ESPE Sil, 3M ESPE). The surfaces were coated with adhesive system (Scotchbond 1, 3M ESPE) and photo-polymerized for 10 s. Resin composite luting cement (RelyX ARC, 3M ESPE) stubs were bonded to substrates and photo-polymerized for 40 s. The test specimens were thermocycled for 0, 1000, 3000, 8000 or 15 000 times (temperature 5–55°C, exposure time 20 s). The shear bond strengths of luting cement to ceramics were measured with a crosshead speed of 1.0 mm/min. ANOVA was used for statistical analysis. ANOVA revealed that both silane and thermocycling affected significantly (p < 0.001) the shear bond strength. Short term hydrolytic stability of acrylate silane was superior. It was concluded that evaluation of bonding requires extended thermocycling.

Extraction and separation studies of silver(I) and copper(II) from their aqueous solution using chemically modified melamine resins

Two modified melamine resins has been prepared and investigated, the modification process took place through the treatment with thiourea to produce R1 or tetraoxalyl ethylenediamine to produce R2. The adsorption behavior of the obtained resins towards Ag(I) and Cu(II) from their aqueous solutions has been studied using batch method. The obtained resins were tested for selective separation between Cu(II) and Ag(I) form their binary mixtures. Resin R1 showed high selectivity towards Ag(I) from Cu(II) solution, while R2 gave a promising results for the selective separation of Cu(II) from Ag(I) solution. Both kinetic and thermodynamic parameters of the adsorption process were obtained. Thermodynamic data indicated that the adsorption process is endothermic spontaneous reaction. Kinetic analysis showed that the adsorption of Ag(I) on R1 is perfectly fit pseudo-first order model, while the adsorption of Cu(II) on R2 is perfectly fit pseudo-second order one. The interaction mechanism between metal ion and active sites has been interpreted as chelation. Durability of resins was estimated from column studies. These parameters indicated that the prepared resins have a good efficiency for repeated use.

Effects from Applying Adhesive Agents onto Silanated Porcelain Surface on the Resin Bond Durability

This study examined the effects on the bond durability of resins arising from the application of adhesive agent on porcelain surface, silanated by a ceramic primer consisting of gamma-methacryloxypropyltrimethoxysilane (gamma-MPTS), by comparing shear bond strengths before and after thermocycling. When an adhesive agent was applied to a porcelain surface which had been silanated by a ceramic primer for 10 seconds, a significant reduction in resin bonding durability was observed. Extending the silanating period of the ceramic primer to 60 minutes resulted in an increase in resin bonding durability to the porcelain surface. However, the effect on resin bonding durability resulting from the application of adhesive agent was nearly the same as that without adhesive agent application, even though the porcelain surface was silanated for 60 minutes. In other words, positive effects arising from adhesive agent application on resin bonding durability were not observed.