Acid-etching Pretreatment Research Articles

To date or not to date? A comparison of different 14C pretreatment methods applied to archeological marine shells from Vale Boi (Portugal)

AbstractMollusk shells are often found in archeological sites, given their great preservation potential and high value as a multipurpose resource, and they can often be the only available materials useful for radiocarbon (14C) dating. However, dates obtained from shells are often regarded as less reliable compared to those from bones, wood, or charcoals due to different factors (e.g., Isotope fractionation, reservoir effects etc.). The standard acid etching pretreatment for mollusk shells is the most used in many 14C laboratories, although another protocol known as CarDS (Carbonate Density Separation) was introduced just over a decade ago. We compare these two methods with two newly proposed methods for intracellular organic matrix extraction. We applied all four methods to samples selected from different archeological layers of the well-known Upper Paleolithic site of Vale Boi, rich in mollusk specimens throughout the stratigraphic sequence. Here we compare our results to previous dates to determine which of these pretreatment methods results in the most reliable 14C dates. Based on the results of this study, all four methods gave inconsistent ages compared to previous dates and the stratigraphic attribution.

Effect of acid corrosion on the surface roughness and floatability of magnesite and dolomite

To modify surface roughness and improve flotation performance, hydrochloric acid etching pretreatment was performed on magnesite and dolomite. Flotation tests disclosed that acid corrosion improved the flotation kinetics and flotation recovery rates of magnesite and dolomite. Under pulp pH 10 and sodium oleate (NaOl) concentration 20 mg·L−1, the flotation recovery rates of magnesite and dolomite after acid etching increased by 31.05% and 29.20%, respectively, compared with those before acid etching. Adsorption density tests proved that the adsorption density of NaOl on magnesite and dolomite was higher after acid etching than before acid etching, implying that acid etching drives NaOl adsorption. Zeta potential analysis revealed that acid etching reduces the point of zero charge of magnesite and dolomite. Atomic force microscopy and X-ray photoelectron spectroscopy results demonstrated that acid corrosion modified the surface roughness of magnesite and dolomite, increasing the magnesium (Mg) content on the magnesite surface and the calcium and Mg contents on the dolomite surface. Contact angle measurements indicated that acid corrosion slightly reduced the contact angle between magnesite and dolomite. With NaOl present on the surface, the contact angles of magnesite and dolomite after acid etching significantly increased compared with those before acid etching. Therefore, acid etching is effective in improving the floatability of magnesite and dolomite.

Interface Bonding Properties and Mechanism of Steel Fiber and Hot Melt Adhesive via Interface Design Engineering.

Steel fiber textile, which is composed of steel fibers and glass fibers, has a support layer impregnated with hot melt adhesive (HMA). During long-term service, the bonding force between the steel fiber/HMA system interfaces is poor. In order to improve the bond strength and durability of the interface, this paper introduced sandblasting, acid-etching, and phosphating treatments on the surface of the steel fibers. Also, the effects of these three pretreatment methods on the bond strength of the steel fiber/HMA interface were investigated. The results indicate that the interfacial bond strength of composites made from steel fibers is improved via surface treatment. Under a hydrothermal and simulated concrete pore solution environment, the durability of the steel fiber/HMA interface after sandblasting and acid-etching pretreatment is not as good as that after phosphating pretreatment. The mechanical properties of the phosphating/HMA composite were maintained at 4.56 and 2.24 times compared to those of the untreated/HMA composite, respectively. This is because the pinning effect formed by the phosphating film on the surface of steel fibers at the interface of steel fiber/HMA can serve as a physical barrier against corrosion, preventing the invasion of chloride ions and water vapor and improving the durability of the interface.

Design of hybrid La1-xCexCoO3-δ catalysts for lean methane combustion via creating active Co and Ce species

The catalytic activity of perovskite-typed catalysts depends on both the surface properties and bulk structure. Herein, we report a facile strategy to induce surface reconstruction and lattice distortion of the La1-xCexCoO3-δ catalysts via acid-etching pretreatment, ultimately realizing superior performance for catalytic combustion of lean methane, even in the presence of steam and hydrogen sulfide. The exsolution of small Ce and Co oxides (ca. 5 nm) from the perovskite were found on the surface of the La1-xCexCoO3-δ catalysts to form a hybrid structure after the acid-etching, which interact with the perovskite bulk to create more Co3+ and surface absorbed oxygen as active sites for methane combustion. It is also found that Ce species can be embedded in the crystal lattice and decorated on the surface of the catalysts after the acid-etching, which may enhance the formation of surface absorbed oxygen and the redox ability of Co3+/Co2+ pair. This results in high catalytic activity (T90 = 486 ℃) with a space velocity of 30,000 mL·g−1·h−1. Otherwise, the weak ability of hydroxyl species adsorbed on the surface of acid-etched catalysts restrain further adsorption of water molecules, improving the stability of methane combustion in the presence of water vapour. The increase in CeO2 content on the surface due to acid etching also contributes to the catalyst’s resistance to sulfur poisoning. The present work may provide a new strategy for the synthesis of hybrid perovskite catalysts with excellent catalytic performance, stability and resistance to impurities poisoning.

Shear Bond Strength Of Etch And Rinse Adhesives To Dentin: Comparison Of Bond Strength After Acid And Papacarie Pre-Treatment.

Papacarie pre-treatment of dentin surface has been reported to exhibit good bond strength values between dentin and composites. Its desirable properties like high pH, sites specify and anti-inflammatory response makes it a future material in place acid etching pre-treatment. Acid etching may cause sensitivity and collapse of dentinal matrix. This in-vitro study involved, 60 caries free extracted premolars, randomly divided into three groups. Control Group (Group A) No pre-treatment of dentin prior adhesive application. Experimental Group B acid etchant was applied before adhesive application. Experimental Group C Papacarie was used as a pre-treatment agent. All these specimens were tested for shear bond strength with the help of Universal Testing Machine. All the collected data was entered in SPSS version 20.0. ANOVA was used to determine the mean SBS (Shear Bond strength) values of control and experimental groups. The mean shear bond strength of material was 7.74±0.47 in group A, 17.80±1.43 in group B and 15.11±0.70 in group C. Group B showing better strength than other two groups. The study provides information about longevity of composite restorations and may help in extending the clinical usage of papacarie to avoid harmful effects of acid etching on dentin and pulpal tissue.

Tuning the Surface Characteristic of Al-Si Alloys and Its Impacts on the Formation of Micro Arc Oxidation Layers

Aluminum Silicon (Al-Si) alloys are the most important among cast alloys and have widespread application. The β-Si phase is detrimental to the growth of micro arc oxidation (MAO) layers on Al-Si alloys. In this paper, the β-Si in the skin layer of different Al-Si alloys was removed by an acid etching pretreatment. Then, the impacts of different etching condition on their MAO process were investigated. Results show that, as etching time was prolonged, the Si content on the surface of Al-12 Si was decreased greatly (less than 0.5 wt.%), and the average size of pores left on the sample surface was increased gradually. This then led to the occurrence of some bigger and more drastic discharge sparks at the earlier oxidation stage. The corresponding layers had a higher ratio of Al2O3 and better corrosion resistance after 30 min of oxidation. Moreover, a 60 s etching pretreatment benefitted and boosted the growth rate and energy efficiency of layers on the Al-9 Si, Al-12 Si and Al-15 Si alloys. Such pretreatment was believed to be applicable to restrain the negative effects of Si on the MAO of different Al-Si alloys.

Influence of Hydrofluoric and Nitric Acid Pre-Treatment and Type of Adhesive Cement on Retention of Zirconia Crowns.

Background: The aim of this study was to test the impact of hot acids etching and two types of adhesive cement on the retention of zirconia crowns. Methods: Forty maxillary premolars were prepared, and zirconia crowns were designed and fabricated with proximal extensions, then divided into 4 groups (n = 10). Group AP; the crowns were air-abraded and cemented using Panavia SA Cement. Group AL; the crowns were air- abraded and cemented using GC LinkForce. Group AHP; the crowns were air-abraded, etched with the hot acids (48% hydrofluoric acid and 69% nitric acid), and cemented using Panavia SA Cement. Group AHL; the crowns were air-abraded, etched with the hot acids, and cemented using GC LinkForce. Each zirconia crown was pre-treated and bonded to its corresponding tooth. After thermocycling (5–55 °C/10,000), the retention test was performed and the load required to dislodge the crown was reported in Newton (N), and mode of failure was recorded. The retention strength (MPa) was calculated for each tested variable and statistically analyzed. Results: Group AHP showed the highest mean value of the retention strength, followed by group AP then group AHL. Group AL showed the lowest value. A statistically significant effect (p = 0.001) of the hot acids etching on the retention of zirconia crown was found. Also, there was a significant effect (p = 0.000) of the cement type. The interaction between surface treatment and the cement type has no significant impact (p = 0.882). The main mode of failure for Panavia SA Cement is mixed mode of failure, while for G-CEM LinkForce is adhesive failure. Conclusions: Hot acid etching pre-treatment improved the retention of zirconia crown. Usage of Panavia SA Cement with hot acids etching is effective can be used for adhesive cementation of zirconia crown.

Effects of Pretreatment Methods on the Enamel Surface Improving Sealant Adhesion

Is PlasBeam pretreatment an efficient method to improve sealant adhesion onto the enamel surface?The aim of this study isto investigate the effects induced by three pretreatment techniques used to improve sealant adhesion on the enamel surface, respectively standard acid-etching, UV radiations and a new method based on plasma operating at atmospheric pressure, namely the PlasBeam method.The physical-chemical modifications induced onto the enamel surface by the above pretreatments were analyzed using Contact Angle Measurements and Diffuse Reflectance Spectroscopy.The changes in the enamel surface morphology show that the acid-etching pretreatment is mostly efficient in increasing roughness, but this method stimulates the degradation processes that are well-known and turns down the brillianceof the treated surface. On the other hand, the PlasBeam treatment brings a higher roughness at the contact area between sealant and the enamel surface, compared to the UV radiations pretreatments.Moreover, the PlasBeam improves the hydrophilic character of enamel as a practical solution in enhancing the sealant adhesion to the surface. Related to other effects, it has been noticed that thePlasBeam method generates the most reflective enamel surface, whereas the White/Yellow index reaches the minimum level after a 10 second treatment.

Sandblasting pretreatment for deposition of diamond films on WC-Co hard metal substrates

Sandblasting combined with acid etching was utilized as pretreatment of Co-cemented tungsten carbide substrates for the deposition of chemical vapor deposition (CVD) diamond films. Diamond films were deposited on the pretreated surface as well as on substrates treated by a two-step alkali-acid pretreatment as a contrast. The field emission scanning electron microscopy (FESEM), X-ray diffraction (XRD), Raman spectroscopy, Rockwell hardness tester and turning test were respectively conducted to characterize the pretreated substrates and deposited diamond films. Surface roughness of the treated surface was controlled by adjusting sandblasting parameters. An enhancement of surface roughness and removal of the binder phase were detected on the treated surface. The porous Co-depleted carbide layer caused by sandblasting and acid-etching pretreatment was obviously thinner compared to the two-step pretreatment. The nucleation stage of CVD process was investigated and the nucleation density was obviously enhanced by the sandblasting pretreatment. Indentation tests exhibited an improvement of adhesive strength compared to the two-step pretreatment. Moreover, the XRD patterns showed that the residual stress of diamond films was decreased. The turning tests showed that the diamond coated tools with sandblasting-acid pretreatment exhibited less area of flank wear and film shedding.

Bonding efficacy of a self-adhesive resin cement to enamel and dentin

With the objective to evaluate the bonding efficacy of a new self-adhesive resin cement (RelyX Unicem, 3M ESPE) to enamel and dentin using a shear bonding strengths test with or without acid etching pretreatment, flat buccal dentin surface and mesial/distal enamel surface were made using a high-speed diamond bur. Copper rings were luted using Rely X Unicem (RU; 3M ESPE), Panavia F (PF; Kuraray) or Vitique (VI; DMG). For RU, the shear bonding strengths using GL (Gluma Etch, Heraeus) acid etching pretreatment were also tested. The teeth were placed into copper rings (inner diameter: 16mm, height: 4mm) and embedded in methylmethacrylate resin. The specimens were stored for 24h in distilled water at 37 °C prior to shear bonding strengths testing. In addition, bond failures were examined by optical microscope and categorized as 4 models such as different adhesive, cohesive, or mixed. Shear bonding strengths were calculated by dividing the maximum debonding force over the cross sectional area of each specimen. The Kruskal-Wallis test was used to determine pairwise statistical differences (P < 0.05) in SBS between the experimental groups. For dentin bonding strength, statistical analysis showed that there was no significant difference among RU (12.84 MPa), PF (14.93 MPa) and VI (11.03 MP); and the bonding strengths of them were higher than RU with acid etching pretreatment (9.12 MP). When bonded to enamel, PF (17.99 MP) and VI (17.58 MP) scored significantly higher than RU efficacy. The use of self-adhesive cement RelyX Unicem can obtain the bonding strengths to dentin similar to traditional resin cements. Phosphoric acid etching can improve the bonding strengths of the self-adhesive resin cement to enamel, but was negative for dentin.

Effect of different monomer-based composites and acid etching pre-treatment of enamel on the microleakage using self-etch adhesives systems

Objective. To evaluate quantitatively the marginal microleakage of restorations carried out with self-etching adhesives with or without prior phosphoric enamel acid etching of silorane or methacrylate resin-based composite restorations subjected to thermal cycling. Materials and methods. Forty cavities were prepared at the proximal surface of bovine incisors and randomly divided according to the etching of the enamel and restorative system used. The groups were restored with methacrylate [Adper SE Plus adhesive (3M ESPE) + Filtek Z250 (3M ESPE)] or silorane [Filtek LS adhesive (3M ESPE) + Filtek LS composite (3M ESPE)] restorative systems, light-cured using a LED unit (Bluephase 16i, Vivadent). After restorative procedure and thermocycling (1000 cycles), the specimens were immersed in methylene blue for 2 h. The specimens were triturated and the powder was used for analysis in an absorbance spectrophotometer. Data were statistically analyzed by 2-way ANOVA (alpha = 0.05). Results. No statistical difference between the restorative materials tested with or without previous acid etching of enamel in Class II marginal microleakage was observed (p > 0.05). Conclusions. The use of acid etching prior to self-etching adhesives did not interfere on the microleakage of methacrylate- or silorane-based restorations.

Multiscale characterization of partially demineralized superficial and deep dentin surfaces

The objective of this study was to address the following question: 'Which properties are modified in partially demineralized surfaces, compared with non-demineralized dentin surfaces, following orthophosphoric acid-etching as performed in clinical procedures?'. For this purpose, the complementary techniques atomic force microscopy/spectroscopy, scanning electron microscopy, energy-dispersive X-ray spectroscopy, and contact angle measurements were used to provide a multiscale characterization of the dentin substrate undergoing the acidic preconditioning designed to enhance wetting. Special attention was given to the influence of the etching pretreatment on the nanomechanical properties at different levels of dentin surfaces, in both dry and hydrated conditions. The four-sided pyramid model (extended Hertz contact model) proved to be accurate for calculating the apparent Young's modulus, offering new information on the elasticity of dentin. The modulus value notably decreased following etching and surface hydration. This study underlines that after the acid etching pretreatment the contribution of the nanomechanical, morphological, and physicochemical modifications has a strong influence on the dentin adhesion properties and thus plays a significant role in the coupling of the adhesive-resin composite build-up material at the dentin surface.

An evaluation of the penetration of peroxide from tooth-whitener

The purpose of this study was to clarify the effects of peroxide on teeth after the tooth-whitenerapplication. An artificial root canal was prepared using the crown of human incisors filled with phosphate buffer solution. Tooth-whitener containing 30% hydrogen peroxide or 35% carbamide peroxide was applied according to the instructions with or without acid-etching pretreatment. Luminol-chemiluminescence was used to measure the quantity of peroxide that penetrated into the buffer within the root canal. The penetrated peroxide quantity ranged from 7 μM to 100.5 μM. The penetration quantity for the hydrogen peroxide-applied group was about 1.6-fold greater than that for the carbamide-applied group. The penetration quantity for the acid-etching pretreatment group exceeded about 4-fold greater than that of the non-pretreatment group. The whitener containing hydrogen peroxide consists of liquid and powder. Qualitative analysis of powder component of the whitener with EPMA showed that it contained Fe and Cu ions. This finding suggests that whitener affects on the tooth by means of hydrogen peroxide itself or the oxygen radical that generated with Fe or Cu ion. Hence, these findings suggest that the penetration of peroxide from whitener applied to the tooth surface might cause some discomfort after whitening treatment.

Liquid crystalline adhesives for polypropylene joints

This study was devoted to the investigation of the adhesion of epoxy resins to polypropylene adherends. In particular, the study was carried out as follows: synthesis of both a liquid crystalline (LC) and a bisphenol-A-based resin, their characterization and their further evaluation as adhesives for polypropylene adherends. This was done in order to evaluate the difference between an LC epoxy resin and an isotropic one in adhesive applications. The adherends chosen were neat polypropylene (PP) and polypropylene reinforced with 20 and 40 wt% talc (PP20 and PP40, respectively). The effect of two different pre-treatments (simple degreasing and acid etching) on the polypropylene adherends was also evaluated. It was shown that the adhesion strength of the liquid crystalline adhesive was higher compared to that of the isotropic one. The higher adhesion was related to the extra ductility demonstrated by the LC epoxy resin, which was due to its particular microstructure. Moreover, the acid etching pre-treatment performed on polypropylene adherends prior to bonding improved the adhesion at the interface with the resin. The increased stiffness of the adherends due to the presence of talc turned out to be beneficial to obtain more resistant joints.

Microleakage of composite restorations after acid or Er-YAG laser cavity treatments

Objectives: The purpose of this study was to compare microleakage of Class V restorations following acid, laser or laser and acid treatment of cavity walls. Methods: Standardized lingual and buccal Class V preparations were made in 18 human extracted third molars. The preparations were randomly assigned to three equal groups ( n=12). Group 1: cavities were treated with 35% phosphoric acid. Group 2: cavities were irradiated with an Er-YAG laser at 2 Hz and 250 mJ on dentin and 300 mJ on enamel, with water cooling. Group 3: cavities were irradiated with the laser before acid etching. Scotchbond 1 Adhesive System and Z100 resin composite were used for restorations. The specimens were stored in water for 24 h at 37°C and thermally cycled (500×) between 6–60°C. After 24 h immersion in 0.5% basic fuchsin, dye penetration was recorded according to an ordinal scale. Data were analysed using non-parametric statistical tests (Kruskal–Wallis and Mann–Whitney). Results: On the occlusal walls, microleakage in acid etched cavities was significantly lower than that achieved after laser treatment ( P<0.001) or after both treatments ( P<0.05). On the gingival walls, no statistical differences were found. Significance: Laser irradiation of enamel is not a valid alternative to acid-etching pretreatment for resin composite materials adhesion. Acid etching alone gave the lowest microleakage at the occlusal margin. No differences were found for microleakage on gingival wall, although lased dentin surfaces presented several characteristics that appear to be advantageous for bonding.

Effect of a room temperature sodium dichromate/sulphuric acid etching pretreatment on the durability of aluminium alloy bonded joints

Practical constraints may restrict the method of surface pretreatment of aluminium alloy surfaces prior to bonding, and a need then arises for simpler techniques than those normally carried out, without a significant decrease in long term environmental durability of the bonded components. It is shown that use of the conventional sodium dichromate/sulphuric acid etching process at room temperature for a longer time, rather than at the specified 60–65°C, can produce equally durable joints and, with the particular alloy composition investigated, appears to show an improvement. Two cold curing modified epoxy adhesives were used to compare the performance of the hot and cold etching processes, respectively, and some limited testing was also carried out with several hot curing adhesives. Joint durability was assessed by water immersion of lap shear specimens and by wedge testing.