The Experts below are selected from a list of 84 Experts worldwide ranked by ideXlab platform
Daniel De La Fuente - One of the best experts on this subject based on the ideXlab platform.
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The settling of critical levels of soluble salts for painting
Elsevier, 2013Co-Authors: Daniel De La Fuente, Bohm M., Houyoux C., Rohwerder M., Morcillo ManuelAbstract:The presence of hydrosoluble species, mainly chlorides and sulphates, at the metal/paint interface promotes Osmotic Blistering of the coating and underfilm metallic corrosion when the concentration of the soluble salts exceeds a critical level. Both processes can lead to the deterioration of the paint system in a very short period of time. The International Standards Organization (ISO) has for some time been trying to develop a standard about guidance safe levels for water-soluble salt contamination before the application of paints and related products. However, it is difficult to set acceptable unique levels since each type of coating and thickness varies in susceptibility to soluble salt degradation and also the exposure conditions vary. In this study, by a variety of accelerated and natural weathering trials, realistic series of limits of soluble salt have been provided depending on the coating systems and exposure conditions. The results show that the generalised levels suggested in the draft version of the ISO standard are far too low compared with the critical levels obtained here. It is suggested that higher levels could be defined, which would save costs and time. © 2006 Elsevier B.V. All rights reserved.Peer Reviewe
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Scanning kelvin probe study on the stability of the steel/coating interfaces contaminated by soluble salts
Trans Tech Publications, 2013Co-Authors: Daniel De La Fuente, Rohwerder M., Chico Belén, Morcillo ManuelAbstract:The presence of hydrosoluble species, mainly chlorides and sulphates, at the metal/paint interface promotes Osmotic Blistering of the coating and underfilm metallic corrosion when the concentration of the soluble salts exceeds a critical level due to the accelerated entrance of water to the interface. Loss of adhesion and cathodic disbondment can be also consequences of the presence of soluble salts. These processes can lead to the deterioration of the paint system in a very short period of time. However, since the interface is not easily accessible by experiment, not much is known about interfacial structure, reactions and the processes causing degradation. Scanning Kelvin Probe (SKP) is an ideal tool for the in situ monitoring of the degradation processes at the buried interface. On the other hand, for an in-depth understanding it is important that the superposition of the effects of all different parameters involved can be disentangled. Hence, it is important to design experiments focussing on individual aspects of the complex system. A study of the fundamental aspects of the stability of the contaminated buried steel/coating interfaces, specially focused on the initial stages of Blistering and underfilm corrosion, has been carried out. Results of the characterization study performed with a height-regulated SKP (HR-SKP) on surfaces contaminated at the interface by different salt concentrations with well defined crystal size and distribution are shown.Peer Reviewe
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Methods for salt contamination of steel corrosion products: A characterization study
Wiley-VCH, 2013Co-Authors: Daniel De La Fuente, Morcillo Manuel, Bohm M., Houyoux C., Rohwerder M.Abstract:It is known that for painted metals the presence of hydrosoluble species within the layer of atmospheric corrosion products, mainly chlorides and sulphates, beneath the coating promotes Osmotic Blistering and underfilm metallic corrosion when the concentration of the soluble salts exceeds a critical level. However, a more in-depth understanding of the coating degradation mechanisms involved especially the initial stages of Blistering, and underfilm corrosion is still missing. On the other hand, from the technical point of view, the determination of safe critical limits for soluble salt contamination at the interface is also necessary. Hence, new methods for artificial saline contamination of steel surfaces must be developed. The work presented here shows that the chloride distribution achieved with salt fog cabinet is much closer to the real case of natural contamination than that achieved with the commonly used homogeneous dosing method. Therefore, it should be used for field-technical studies aimed to establish critical levels of this contaminant at the steel/coating interfaces. On the other hand, it has been also proven that by means of the so-called 'impactor' and 'droplet' methods, very low and ultra-low contaminated samples with well defined crystal size and distribution of chloride can be prepared. They are necessary on research works planned by the authors to study the fundamental aspects of the stability of the contaminated buried steel/coating interfaces. © 2007 WILEY-VCH Verlag GmbH & Co. KGaA.Peer Reviewe
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Scanning Kelvin Probe Study on the Stability of the Steel/Coating Interfaces Contaminated by Soluble Salts
Defect and Diffusion Forum, 2009Co-Authors: Daniel De La Fuente, Michael Rohwerder, Belén Chico, Manuel MorcilloAbstract:The presence of hydrosoluble species, mainly chlorides and sulphates, at the metal/paint interface promotes Osmotic Blistering of the coating and underfilm metallic corrosion when the concentration of the soluble salts exceeds a critical level due to the accelerated entrance of water to the interface. Loss of adhesion and cathodic disbondment can be also consequences of the presence of soluble salts. These processes can lead to the deterioration of the paint system in a very short period of time. However, since the interface is not easily accessible by experiment, not much is known about interfacial structure, reactions and the processes causing degradation. Scanning Kelvin Probe (SKP) is an ideal tool for the in situ monitoring of the degradation processes at the buried interface. On the other hand, for an in-depth understanding it is important that the superposition of the effects of all different parameters involved can be disentangled. Hence, it is important to design experiments focussing on individual aspects of the complex system. A study of the fundamental aspects of the stability of the contaminated buried steel/coating interfaces, specially focused on the initial stages of Blistering and underfilm corrosion, has been carried out. Results of the characterization study performed with a height-regulated SKP (HR-SKP) on surfaces contaminated at the interface by different salt concentrations with well defined crystal size and distribution are shown.
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Fundamental investigation on the stability of the steel/coating interfaces contaminated by submicroscopic salt particles
Progress in Organic Coatings, 2008Co-Authors: Daniel De La Fuente, Michael RohwerderAbstract:It is known that the presence of hydrosoluble species, mainly chlorides and sulphates, at the metal/paint interface, promotes Osmotic Blistering of the coating and underfilm metallic corrosion when the concentration exceeds a critical level. However, since the interface is not easily accessible by experiment, not much is known about interfacial structure, reactions and the processes causing degradation. Scanning Kelvin Probe (SKP) is an ideal tool for the in situ monitoring of the degradation processes at the buried interface. In the present paper, a study of the fundamental aspects of the stability of the contaminated buried steel/coating interfaces, specially focused on the initial stages of Blistering and underfilm corrosion, has been carried out. Results of the characterization study performed with a height-regulated SKP (HR-SKP) on coated steel contaminated at the interface by different salt concentrations with well-defined crystal size and distribution are shown. An effect of crystal size and distribution has been observed. While, small crystals or low density of salt spots do not show macroscopic Blistering, bigger crystals or a local accumulation of them can cause significant de-adhesion and macroscopic Blistering.
Morcillo Manuel - One of the best experts on this subject based on the ideXlab platform.
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Anticipated levels of soluble salts remaining on rusty steel prior to painting
Springer, 2013Co-Authors: Flores S., Morcillo ManuelAbstract:The presence of water-soluble contaminants (particularly sulphates and chlorides) at the steel/paint interface is know to have detrimental effects on the performance of most of the paint systems. The development of rust under the paint fihn and Osmotic Blistering are observed frequently at an early stage in paint coatings applied over contaminated rustry steel. Is there a threshold value for soluble salt concentrations above which unacceptably rapid deterioration of the paint film starts to occur? So it seems, judging by the results of some studies,Peer Reviewe
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The settling of critical levels of soluble salts for painting
Elsevier, 2013Co-Authors: Daniel De La Fuente, Bohm M., Houyoux C., Rohwerder M., Morcillo ManuelAbstract:The presence of hydrosoluble species, mainly chlorides and sulphates, at the metal/paint interface promotes Osmotic Blistering of the coating and underfilm metallic corrosion when the concentration of the soluble salts exceeds a critical level. Both processes can lead to the deterioration of the paint system in a very short period of time. The International Standards Organization (ISO) has for some time been trying to develop a standard about guidance safe levels for water-soluble salt contamination before the application of paints and related products. However, it is difficult to set acceptable unique levels since each type of coating and thickness varies in susceptibility to soluble salt degradation and also the exposure conditions vary. In this study, by a variety of accelerated and natural weathering trials, realistic series of limits of soluble salt have been provided depending on the coating systems and exposure conditions. The results show that the generalised levels suggested in the draft version of the ISO standard are far too low compared with the critical levels obtained here. It is suggested that higher levels could be defined, which would save costs and time. © 2006 Elsevier B.V. All rights reserved.Peer Reviewe
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Scanning kelvin probe study on the stability of the steel/coating interfaces contaminated by soluble salts
Trans Tech Publications, 2013Co-Authors: Daniel De La Fuente, Rohwerder M., Chico Belén, Morcillo ManuelAbstract:The presence of hydrosoluble species, mainly chlorides and sulphates, at the metal/paint interface promotes Osmotic Blistering of the coating and underfilm metallic corrosion when the concentration of the soluble salts exceeds a critical level due to the accelerated entrance of water to the interface. Loss of adhesion and cathodic disbondment can be also consequences of the presence of soluble salts. These processes can lead to the deterioration of the paint system in a very short period of time. However, since the interface is not easily accessible by experiment, not much is known about interfacial structure, reactions and the processes causing degradation. Scanning Kelvin Probe (SKP) is an ideal tool for the in situ monitoring of the degradation processes at the buried interface. On the other hand, for an in-depth understanding it is important that the superposition of the effects of all different parameters involved can be disentangled. Hence, it is important to design experiments focussing on individual aspects of the complex system. A study of the fundamental aspects of the stability of the contaminated buried steel/coating interfaces, specially focused on the initial stages of Blistering and underfilm corrosion, has been carried out. Results of the characterization study performed with a height-regulated SKP (HR-SKP) on surfaces contaminated at the interface by different salt concentrations with well defined crystal size and distribution are shown.Peer Reviewe
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Methods for salt contamination of steel corrosion products: A characterization study
Wiley-VCH, 2013Co-Authors: Daniel De La Fuente, Morcillo Manuel, Bohm M., Houyoux C., Rohwerder M.Abstract:It is known that for painted metals the presence of hydrosoluble species within the layer of atmospheric corrosion products, mainly chlorides and sulphates, beneath the coating promotes Osmotic Blistering and underfilm metallic corrosion when the concentration of the soluble salts exceeds a critical level. However, a more in-depth understanding of the coating degradation mechanisms involved especially the initial stages of Blistering, and underfilm corrosion is still missing. On the other hand, from the technical point of view, the determination of safe critical limits for soluble salt contamination at the interface is also necessary. Hence, new methods for artificial saline contamination of steel surfaces must be developed. The work presented here shows that the chloride distribution achieved with salt fog cabinet is much closer to the real case of natural contamination than that achieved with the commonly used homogeneous dosing method. Therefore, it should be used for field-technical studies aimed to establish critical levels of this contaminant at the steel/coating interfaces. On the other hand, it has been also proven that by means of the so-called 'impactor' and 'droplet' methods, very low and ultra-low contaminated samples with well defined crystal size and distribution of chloride can be prepared. They are necessary on research works planned by the authors to study the fundamental aspects of the stability of the contaminated buried steel/coating interfaces. © 2007 WILEY-VCH Verlag GmbH & Co. KGaA.Peer Reviewe
Michael Rohwerder - One of the best experts on this subject based on the ideXlab platform.
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Scanning Kelvin Probe Study on the Stability of the Steel/Coating Interfaces Contaminated by Soluble Salts
Defect and Diffusion Forum, 2009Co-Authors: Daniel De La Fuente, Michael Rohwerder, Belén Chico, Manuel MorcilloAbstract:The presence of hydrosoluble species, mainly chlorides and sulphates, at the metal/paint interface promotes Osmotic Blistering of the coating and underfilm metallic corrosion when the concentration of the soluble salts exceeds a critical level due to the accelerated entrance of water to the interface. Loss of adhesion and cathodic disbondment can be also consequences of the presence of soluble salts. These processes can lead to the deterioration of the paint system in a very short period of time. However, since the interface is not easily accessible by experiment, not much is known about interfacial structure, reactions and the processes causing degradation. Scanning Kelvin Probe (SKP) is an ideal tool for the in situ monitoring of the degradation processes at the buried interface. On the other hand, for an in-depth understanding it is important that the superposition of the effects of all different parameters involved can be disentangled. Hence, it is important to design experiments focussing on individual aspects of the complex system. A study of the fundamental aspects of the stability of the contaminated buried steel/coating interfaces, specially focused on the initial stages of Blistering and underfilm corrosion, has been carried out. Results of the characterization study performed with a height-regulated SKP (HR-SKP) on surfaces contaminated at the interface by different salt concentrations with well defined crystal size and distribution are shown.
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Fundamental investigation on the stability of the steel/coating interfaces contaminated by submicroscopic salt particles
Progress in Organic Coatings, 2008Co-Authors: Daniel De La Fuente, Michael RohwerderAbstract:It is known that the presence of hydrosoluble species, mainly chlorides and sulphates, at the metal/paint interface, promotes Osmotic Blistering of the coating and underfilm metallic corrosion when the concentration exceeds a critical level. However, since the interface is not easily accessible by experiment, not much is known about interfacial structure, reactions and the processes causing degradation. Scanning Kelvin Probe (SKP) is an ideal tool for the in situ monitoring of the degradation processes at the buried interface. In the present paper, a study of the fundamental aspects of the stability of the contaminated buried steel/coating interfaces, specially focused on the initial stages of Blistering and underfilm corrosion, has been carried out. Results of the characterization study performed with a height-regulated SKP (HR-SKP) on coated steel contaminated at the interface by different salt concentrations with well-defined crystal size and distribution are shown. An effect of crystal size and distribution has been observed. While, small crystals or low density of salt spots do not show macroscopic Blistering, bigger crystals or a local accumulation of them can cause significant de-adhesion and macroscopic Blistering.
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Methods for salt contamination of steel corrosion products: A characterization study
Materials and Corrosion-werkstoffe Und Korrosion, 2007Co-Authors: Daniel De La Fuente, Michael Christian Böhm, C. Houyoux, Manuel Morcillo, Michael RohwerderAbstract:It is known that for painted metals the presence of hydrosoluble species within the layer of atmospheric corrosion products, mainly chlorides and sulphates, beneath the coating promotes Osmotic Blistering and underfilm metallic corrosion when the concentration of the soluble salts exceeds a critical level. However, a more in-depth understanding of the coating degradation mechanisms involved especially the initial stages of Blistering, and underfilm corrosion is still missing. On the other hand, from the technical point of view, the determination of safe critical limits for soluble salt contamination at the interface is also necessary. Hence, new methods for artificial saline contamination of steel surfaces must be developed. The work presented here shows that the chloride distribution achieved with salt fog cabinet is much closer to the real case of natural contamination than that achieved with the commonly used homogeneous dosing method. Therefore, it should be used for field-technical studies aimed to establish critical levels of this contaminant at the steel/coating interfaces. On the other hand, it has been also proven that by means of the so-called ‘impactor’ and ‘droplet’ methods, very low and ultra-low contaminated samples with well defined crystal size and distribution of chloride can be prepared. They are necessary on research works planned by the authors to study the fundamental aspects of the stability of the contaminated buried steel/coating interfaces.
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The settling of critical levels of soluble salts for painting
Progress in Organic Coatings, 2006Co-Authors: Daniel De La Fuente, Michael Rohwerder, Michael Christian Böhm, C. Houyoux, Manuel MorcilloAbstract:The presence of hydrosoluble species, mainly chlorides and sulphates, at the metal/paint interface promotes Osmotic Blistering of the coating and underfilm metallic corrosion when the concentration of the soluble salts exceeds a critical level. Both processes can lead to the deterioration of the paint system in a very short period of time. The International Standards Organization (ISO) has for some time been trying to develop a standard about guidance safe levels for water-soluble salt contamination before the application of paints and related products. However, it is difficult to set acceptable unique levels since each type of coating and thickness varies in susceptibility to soluble salt degradation and also the exposure conditions vary. In this study, by a variety of accelerated and natural weathering trials, realistic series of limits of soluble salt have been provided depending on the coating systems and exposure conditions. The results show that the generalised levels suggested in the draft version of the ISO standard are far too low compared with the critical levels obtained here. It is suggested that higher levels could be defined, which would save costs and time.
Franklin R. Tay - One of the best experts on this subject based on the ideXlab platform.
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Osmotic Blistering in Enamel Bonded with One-step Self-etch Adhesives
Journal of Dental Research, 2004Co-Authors: Franklin R. Tay, C.n.s. Lai, Stefano Chersoni, David H. Pashley, Y.f. Mak, Pietro Suppa, Carlo Prati, Nigel M. KingAbstract:One-step self-etch adhesives behave as permeable membranes after polymerization, permitting water to move through the cured adhesives. We hypothesize that Osmotic Blistering occurs in bonded enamel when these adhesives are used without composite coupling. Tooth surfaces from extracted human premolars were bonded with 5 one-step self-etch adhesives. They were immersed in distilled water or 4.8 M CaCl2, and examined by stereomicroscopy, field-emission/environmental SEM, and TEM. Water blisters were observed in bonded enamel but not in bonded dentin when specimens were immersed in water. They collapsed when water was subsequently replaced with CaCl2. Blisters were absent from enamel in specimens that were immersed in CaCl2 only. Water trees were identified from adhesive-enamel interfaces. Osmotic Blistering in enamel is probably caused by the low water permeability of enamel. This creates an Osmotic gradient between the bonded enamel and the external environment, causing water sorption into the interface.
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Single-step adhesives are permeable membranes.
Journal of Dentistry, 2002Co-Authors: Franklin R. Tay, David H. Pashley, Byoung I Suh, Ricardo M Carvalho, Anut ItthagarunAbstract:Objectives. This study tested the hypotheses that micro-tensile bond strengths of all currently available single-step adhesives to dentine are adversely affected by delayed activation of a light-cured composite, and that such a phenomenon only occurs in the presence of water from the substrate side of the bonded interface. Methods. In experiment I, a control three-step adhesive (All-Bond 2, Bisco) and six single-step adhesives (One-Up Bond F, Tokuyama; EtchP Xeno CF Bond, Sankin; AQ Bond, Sun Medical; Reactmer Bond, Shofu and Prompt L-Pop, 3M ESPE) were bonded to sound, hydrated dentine. A microfilled composite was placed over the cured adhesive and was either light-activated immediately, or after leaving the composite in the dark for 20 min. In experiment II, three single-step adhesives (Etch&Prime 3.0, Xeno CF Bond and AQ Bond) were similarly bonded to completely dehydrated dentine using the same delayed light-activation protocol. In experiment III, a piece of processed composite was used as the bonding substrate for the same three single-step adhesives. The microfilled composite was applied to the cured adhesives using the same immediate and delayed light-activation protocols. Bonded specimens were sectioned for micro-tensile bond strength evaluation. Fractographic analysis of the specimens was performed using SEM. Stained, undemineralised sections of unstressed, bonded specimens were also examined by TEM. Results. When bonded to hydrated dentine, delayed light-activation had no effect on the control three-step adhesive, but significantly lowered the bond strengths of all the single-step adhesives ( p , 0.05). This adverse effect of delayed light-activation was not observed in the three single-step adhesives that were bonded to either dehydrated dentine or processed composite. Morphological manifestations of delayed light-activation of composite in the hydrated dentine bonding substrate were exclusively located along the composite ‐ adhesive interface, and were present as large voids, resin globules and honeycomb structures that formed partitions around a myriad of small blisters along the fractured interfaces. Conclusion. These features resembled of the ‘overwet phenomenon’ that was previously reported along the dentine ‐ adhesive interfaces of some acetone-based three-step adhesives. The cured adhesive layer in single-step adhesives may act as semi-permeable membranes that allow water diffusion from the bonded hydrated dentine to the intermixed zone between the adhesive and the uncured composite. Osmotic Blistering of water droplets along the surface of the cured adhesive layer and emulsion polymerisation of immiscible resin components probably account for the compromised bond strength in single-step adhesives after delayed activation of light-cured composites. q 2002 Elsevier Science Ltd. All rights reserved.
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Single-step adhesives are permeable membranes.
Journal of dentistry, 2002Co-Authors: Franklin R. Tay, David H. Pashley, Byoung I Suh, Ricardo M Carvalho, Anut ItthagarunAbstract:This study tested the hypotheses that micro-tensile bond strengths of all currently available single-step adhesives to dentine are adversely affected by delayed activation of a light-cured composite, and that such a phenomenon only occurs in the presence of water from the substrate side of the bonded interface. In experiment I, a control three-step adhesive (All-Bond 2, Bisco) and six single-step adhesives (One-Up Bond F, Tokuyama; Etch&Prime 3.0, Degussa; Xeno CF Bond, Sankin; AQ Bond, Sun Medical; Reactmer Bond, Shofu and Prompt L-Pop, 3M ESPE) were bonded to sound, hydrated dentine. A microfilled composite was placed over the cured adhesive and was either light-activated immediately, or after leaving the composite in the dark for 20 min. In experiment II, three single-step adhesives (Etch&Prime 3.0, Xeno CF Bond and AQ Bond) were similarly bonded to completely dehydrated dentine using the same delayed light-activation protocol. In experiment III, a piece of processed composite was used as the bonding substrate for the same three single-step adhesives. The microfilled composite was applied to the cured adhesives using the same immediate and delayed light-activation protocols. Bonded specimens were sectioned for micro-tensile bond strength evaluation. Fractographic analysis of the specimens was performed using SEM. Stained, undemineralised sections of unstressed, bonded specimens were also examined by TEM. When bonded to hydrated dentine, delayed light-activation had no effect on the control three-step adhesive, but significantly lowered the bond strengths of all the single-step adhesives (p < 0.05). This adverse effect of delayed light-activation was not observed in the three single-step adhesives that were bonded to either dehydrated dentine or processed composite. Morphological manifestations of delayed light-activation of composite in the hydrated dentine bonding substrate were exclusively located along the composite-adhesive interface, and were present as large voids, resin globules and honeycomb structures that formed partitions around a myriad of small blisters along the fractured interfaces. These features resembled the 'overwet phenomenon' that was previously reported along the dentine-adhesive interfaces of some acetone-based three-step adhesives. The cured adhesive layer in single-step adhesives may act as semi-permeable membranes that allow water diffusion from the bonded hydrated dentine to the intermixed zone between the adhesive and the uncured composite. Osmotic Blistering of water droplets along the surface of the cured adhesive layer and emulsion polymerisation of immiscible resin components probably account for the compromised bond strength in single-step adhesives after delayed activation of light-cured composites. Copyright 2002 Elsevier Science Ltd.
David H. Pashley - One of the best experts on this subject based on the ideXlab platform.
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Osmotic Blistering in Enamel Bonded with One-step Self-etch Adhesives
Journal of Dental Research, 2004Co-Authors: Franklin R. Tay, C.n.s. Lai, Stefano Chersoni, David H. Pashley, Y.f. Mak, Pietro Suppa, Carlo Prati, Nigel M. KingAbstract:One-step self-etch adhesives behave as permeable membranes after polymerization, permitting water to move through the cured adhesives. We hypothesize that Osmotic Blistering occurs in bonded enamel when these adhesives are used without composite coupling. Tooth surfaces from extracted human premolars were bonded with 5 one-step self-etch adhesives. They were immersed in distilled water or 4.8 M CaCl2, and examined by stereomicroscopy, field-emission/environmental SEM, and TEM. Water blisters were observed in bonded enamel but not in bonded dentin when specimens were immersed in water. They collapsed when water was subsequently replaced with CaCl2. Blisters were absent from enamel in specimens that were immersed in CaCl2 only. Water trees were identified from adhesive-enamel interfaces. Osmotic Blistering in enamel is probably caused by the low water permeability of enamel. This creates an Osmotic gradient between the bonded enamel and the external environment, causing water sorption into the interface.
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Osmotic Blistering in enamel bonded with one-step self-etch adhesives
'United States Sports Academy', 2004Co-Authors: Nm King, David H. Pashley, Suppa P, Prati C, Tay Fr, Lai Cns, Chersoni S, Y.f. MakAbstract:One-step self-etch adhesives behave as permeable membranes after polymerization, permitting water to move through the cured adhesives. We hypothesize that Osmotic Blistering occurs in bonded enamel when these adhesives are used without composite coupling. Tooth surfaces from extracted human premolars were bonded with 5 one-step self-etch adhesives. They were immersed in distilled water or 4.8 M CaCl2, and examined by stereomicroscopy, field-emission/environmental SEM, and TEM. Water blisters were observed in bonded enamel but not in bonded dentin when specimens were immersed in water. They collapsed when water was subsequently replaced with CaCl2. Blisters were absent from enamel in specimens that were immersed in CaCl 2 only. Water trees were identified from adhesive-enamel interfaces. Osmotic Blistering in enamel is probably caused by the low water permeability of enamel. This creates an Osmotic gradient between the bonded enamel and the external environment, causing water sorption into the interface.published_or_final_versio
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Single-step adhesives are permeable membranes.
Journal of Dentistry, 2002Co-Authors: Franklin R. Tay, David H. Pashley, Byoung I Suh, Ricardo M Carvalho, Anut ItthagarunAbstract:Objectives. This study tested the hypotheses that micro-tensile bond strengths of all currently available single-step adhesives to dentine are adversely affected by delayed activation of a light-cured composite, and that such a phenomenon only occurs in the presence of water from the substrate side of the bonded interface. Methods. In experiment I, a control three-step adhesive (All-Bond 2, Bisco) and six single-step adhesives (One-Up Bond F, Tokuyama; EtchP Xeno CF Bond, Sankin; AQ Bond, Sun Medical; Reactmer Bond, Shofu and Prompt L-Pop, 3M ESPE) were bonded to sound, hydrated dentine. A microfilled composite was placed over the cured adhesive and was either light-activated immediately, or after leaving the composite in the dark for 20 min. In experiment II, three single-step adhesives (Etch&Prime 3.0, Xeno CF Bond and AQ Bond) were similarly bonded to completely dehydrated dentine using the same delayed light-activation protocol. In experiment III, a piece of processed composite was used as the bonding substrate for the same three single-step adhesives. The microfilled composite was applied to the cured adhesives using the same immediate and delayed light-activation protocols. Bonded specimens were sectioned for micro-tensile bond strength evaluation. Fractographic analysis of the specimens was performed using SEM. Stained, undemineralised sections of unstressed, bonded specimens were also examined by TEM. Results. When bonded to hydrated dentine, delayed light-activation had no effect on the control three-step adhesive, but significantly lowered the bond strengths of all the single-step adhesives ( p , 0.05). This adverse effect of delayed light-activation was not observed in the three single-step adhesives that were bonded to either dehydrated dentine or processed composite. Morphological manifestations of delayed light-activation of composite in the hydrated dentine bonding substrate were exclusively located along the composite ‐ adhesive interface, and were present as large voids, resin globules and honeycomb structures that formed partitions around a myriad of small blisters along the fractured interfaces. Conclusion. These features resembled of the ‘overwet phenomenon’ that was previously reported along the dentine ‐ adhesive interfaces of some acetone-based three-step adhesives. The cured adhesive layer in single-step adhesives may act as semi-permeable membranes that allow water diffusion from the bonded hydrated dentine to the intermixed zone between the adhesive and the uncured composite. Osmotic Blistering of water droplets along the surface of the cured adhesive layer and emulsion polymerisation of immiscible resin components probably account for the compromised bond strength in single-step adhesives after delayed activation of light-cured composites. q 2002 Elsevier Science Ltd. All rights reserved.
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Single-step adhesives are permeable membranes.
Journal of dentistry, 2002Co-Authors: Franklin R. Tay, David H. Pashley, Byoung I Suh, Ricardo M Carvalho, Anut ItthagarunAbstract:This study tested the hypotheses that micro-tensile bond strengths of all currently available single-step adhesives to dentine are adversely affected by delayed activation of a light-cured composite, and that such a phenomenon only occurs in the presence of water from the substrate side of the bonded interface. In experiment I, a control three-step adhesive (All-Bond 2, Bisco) and six single-step adhesives (One-Up Bond F, Tokuyama; Etch&Prime 3.0, Degussa; Xeno CF Bond, Sankin; AQ Bond, Sun Medical; Reactmer Bond, Shofu and Prompt L-Pop, 3M ESPE) were bonded to sound, hydrated dentine. A microfilled composite was placed over the cured adhesive and was either light-activated immediately, or after leaving the composite in the dark for 20 min. In experiment II, three single-step adhesives (Etch&Prime 3.0, Xeno CF Bond and AQ Bond) were similarly bonded to completely dehydrated dentine using the same delayed light-activation protocol. In experiment III, a piece of processed composite was used as the bonding substrate for the same three single-step adhesives. The microfilled composite was applied to the cured adhesives using the same immediate and delayed light-activation protocols. Bonded specimens were sectioned for micro-tensile bond strength evaluation. Fractographic analysis of the specimens was performed using SEM. Stained, undemineralised sections of unstressed, bonded specimens were also examined by TEM. When bonded to hydrated dentine, delayed light-activation had no effect on the control three-step adhesive, but significantly lowered the bond strengths of all the single-step adhesives (p < 0.05). This adverse effect of delayed light-activation was not observed in the three single-step adhesives that were bonded to either dehydrated dentine or processed composite. Morphological manifestations of delayed light-activation of composite in the hydrated dentine bonding substrate were exclusively located along the composite-adhesive interface, and were present as large voids, resin globules and honeycomb structures that formed partitions around a myriad of small blisters along the fractured interfaces. These features resembled the 'overwet phenomenon' that was previously reported along the dentine-adhesive interfaces of some acetone-based three-step adhesives. The cured adhesive layer in single-step adhesives may act as semi-permeable membranes that allow water diffusion from the bonded hydrated dentine to the intermixed zone between the adhesive and the uncured composite. Osmotic Blistering of water droplets along the surface of the cured adhesive layer and emulsion polymerisation of immiscible resin components probably account for the compromised bond strength in single-step adhesives after delayed activation of light-cured composites. Copyright 2002 Elsevier Science Ltd.
