The Effect of Conditioning on Adhesion to Human Dentin

The effect of conditioning dentin was investigated using ethyleneglycol bis(aminoethylether) tetraacetic acid (EGTA) and three proprietary agents containing ethylenediamine tetraacetic acid (EDTA), maleic acid and dipentaerythritol pentaacrylate phsophoric acid ester (PENTA). Ground dentin was treated with EGTA or one of the three proprietary agents. After adhering composite resin to treated surfaces, the shear bond strength (SBS) was determined with and without thermal stress. Scanning electron and atomic force microscopies were used to assess morphological effects of each of the agents, while low resolution X-ray photoelectron spectroscopy (XPS) was employed to evaluate elemental changes due to treatment. Mean bond strength was greatest for the PENTA-conditioned surfaces. EDTA and maleic acid demineralized the dentin surface while the agent containing PENTA produced an adherent surface film. The XPS survey showed a reduction in Ca and an increase in N for agents containing EGTA, EDTA and maleic acid, while a simultaneous reduction in both these species was observed for PENTA. EGTA did not improve adhesion for systems which were based on smear layer removal and substrate demineralization. For the PENTA-based system, which relied on the development of a molecular overlayer, EGTA degraded bond strength.     

高强度和高特性能杂化牙质层的研究

研究了2-甲基丙烯酰氧乙基苯基磷酸phenyl-P／2-羟乙基甲基丙烯酸酯(HEMA)丙酮底剂和用1,2-乙二胺四乙酸盐(EDTA5—10)调湿剂在湿粘接时对调湿牙质表面的综合影响。实验结果预示,藉此将得到高粘接强度和高特性的杂化牙质层。     

Influence of Dentin Smear Layer Created by Chemo-Mechanical or Bur Excavation Methods on Adhesion of Self-Etching Primers and a Conventional Adhesive

This study evaluated the influence of chemo-mechanical or bur excavation methods on bond strength of dentin bonding agents, micromorphology of the treated-dentin surfaces, and the bonded interfaces. Smear layer-free surfaces were used as control. The methods of cavity preparation (chemo-mechanical and rotary burs) were used under specific parameters and four commercial dentin bonding agents (three two-step self-etching primers and one “etch-and-rinse” adhesive system) were applied to treated surfaces, according to manufacturers' instructions. Composite blocks were built on bonded surfaces and restored teeth were vertically, serially sectioned to obtain bonded slices for interfacial micromorphologic analysis or to produce beam specimens for micro-tensile bond testing. A clear difference of the preparation of dentin surfaces and formation of hybrid layer and resin tags are noted. The use of burs or chemo-mechanical methods did not affect the bond strength for etch-and-rinse system and for a self-etching primer with a very low pH (0.5). However, dentin surface preparations decreased the bond strength for the milder versions (pH of around 2) of self-etching adhesive systems. The manner of dentin preparation prior to bonding procedures can influence the effectiveness of some self-etching primers, which dissolve the smear layer and dentin surface only partially.     

Influence of Dentin Smear Layer Created by Chemo-Mechanical or Bur Excavation Methods on Adhesion of Self-Etching Primers and a Conventional Adhesive

This study evaluated the influence of chemo-mechanical or bur excavation methods on bond strength of dentin bonding agents, micromorphology of the treated-dentin surfaces, and the bonded interfaces. Smear layer-free surfaces were used as control. The methods of cavity preparation (chemo-mechanical and rotary burs) were used under specific parameters and four commercial dentin bonding agents (three two-step self-etching primers and one “etch-and-rinse” adhesive system) were applied to treated surfaces, according to manufacturers' instructions. Composite blocks were built on bonded surfaces and restored teeth were vertically, serially sectioned to obtain bonded slices for interfacial micromorphologic analysis or to produce beam specimens for micro-tensile bond testing. A clear difference of the preparation of dentin surfaces and formation of hybrid layer and resin tags are noted. The use of burs or chemo-mechanical methods did not affect the bond strength for etch-and-rinse system and for a self-etching primer with a very low pH (0.5). However, dentin surface preparations decreased the bond strength for the milder versions (pH of around 2) of self-etching adhesive systems. The manner of dentin preparation prior to bonding procedures can influence the effectiveness of some self-etching primers, which dissolve the smear layer and dentin surface only partially.     

Chemical Reactions Between Dentin and Bonding Agents

The possible interaction between dentin and a proprietary dentin bonding agent (DBA), Gluma, was studied by Phase Photoacoustic FTIR. The determination of the existence and nature of a chemical bond between the DBA and the substrate can be of great importance in explaining the performance of these agents. Human dentin was treated by solutions of 2-hydroxyethyl methacrylate (HEMA), glutaraldehyde and a combination of both (Gluma Primer). Spectra of dentin samples treated with 35% and 100% HEMA as well as Gluma Primer show loss of both the hydroxyl (O-H stretch) and methylene (CH₂ stretches) peaks from HEMA while other peaks are retained, even after thorough washing. This indicates a reaction between HEMA and the collagenous fraction of dentin.     

Bond strength and adhesive interface analysis using EDTA as a dentin conditioner

This study evaluated dentin bond strength and dentin-resin interfacial morphology using phosphoric acid-etching and EDTA-conditioning. The occlusal enamel of twenty-four human third molars was removed to expose the dentin surfaces, which were polished with a SiC paper (600 grit). Teeth were randomly divided into three groups (n = 8): etching with 37% phosphoric acid (15 s), conditioning with 0.1 M EDTA (60 s) and 0.5 M EDTA (120 s). Adhesive (XP Bond, Dentsply) was applied and three layers (2 mm each) of composite (EsthetX, Dentsply) were placed and light-activated separately (20 s). Teeth were sectioned to obtain specimens for the microtensile bond strength test (1 mm² at cross section). Half of the specimens was tested in a universal testing machine (EZ Test, Shimadzu) after 24 h and the other half after storage for 10 months. Failure mode and adhesive interface were analyzed using scanning electron microscopy. Data were analyzed by mixed models for repeated measures (PROC MIXED) and Tukey-Kramer test, considering a significance level of 5%. Mean bond strength values (SD) after 24 h and 10 months were, respectively (in MPa): phosphoric acid: 37.3 (7.7) / 33.9 (6.7); 0.1 M EDTA: 14.7 (7.3) / 15.1 (10.1); 0.5 M EDTA: 25.1 (7.7) / 21.1 (14.1). Dentin treatment with EDTA and phosphoric acid resulted in hybrid layer and resin tags formation. Mixed failures were prevalent for all groups tested after 24 h. Storage for 10 months changed the failure mode for the 0.5 M EDTA group to adhesive failure (between dentin and bonding agent). EDTA applied for 60 s yielded lower bond strength results compared to phosphoric acid and EDTA (120 s), but there was no significant reduction after 10 months of storage for any of the tested groups.     

Chemical Reactions Between Dentin and Bonding Agents

The possible interaction between dentin and a proprietary dentin bonding agent (DBA), Gluma, was studied by Phase Photoacoustic FTIR. The determination of the existence and nature of a chemical bond between the DBA and the substrate can be of great importance in explaining the performance of these agents. Human dentin was treated by solutions of 2-hydroxyethyl methacrylate (HEMA), glutaraldehyde and a combination of both (Gluma Primer). Spectra of dentin samples treated with 35% and 100% HEMA as well as Gluma Primer show loss of both the hydroxyl (O-H stretch) and methylene (CH₂ stretches) peaks from HEMA while other peaks are retained, even after thorough washing. This indicates a reaction between HEMA and the collagenous fraction of dentin.     

Role of dentin cross-linking agents in optimizing dentin bond durability

The present work compared the effects of 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide hydrochloride (EDC-HCl) and ultraviolet (UV)- or blue light-activated riboflavin cross-linking agents on resin–dentin micro-tensile bond strength and nanoleakage in bonds produced using a two-step, etch-and-rinse adhesive after three storage intervals (24 h, 6 months, and 12 months). Forty eight extracted human third molars were used to investigate micro-tensile bond strength and interfacial nanoleakage in resin–dentin bonds created using Adper Single Bond 2, with or without pretreatment of acid-etched dentin surfaces. Either 0.5 M EDC-HCl or 1% riboflavin-5-phosphate activated by blue or UV light were used as cross-linking agents. Samples were evaluated after storage for 24 h, 6 months, or 12 months in distilled water at 37 °C. Statistical analyses revealed that 12 months of storage resulted in significant decreases in the bond strength of the controls (p < 0.003), with significant increases in their silver nanoleakage (p < 0.05), compared with the groups subjected to dentin pretreatment with either EDC-HCl or light-activated 1% riboflavin. Despite the significant drop in bond strength after 6 months’ storage in all experimental groups compared with the 24-h bond strength (p < 0.05), there was a further non-significant drop in bond strength after 12 months in samples treated with EDC-HCl and UV-activated 1% riboflavin (p > 0.05). Dental collagen cross-linking induced by UV- or blue light-activated 1% riboflavin or EDC-HCl enhanced the durability and strength of the resin–dentin bond.     

Bond strength of glass carbomer material to enamel and dentin following different surface pretreatments

Objective: Enamel and dentin bond strengths of restorative glass carbomer material were determined by shear bond strength (SBS) test after different surface treatments in this study.

Materials and methods: Flat enamel and dentin surfaces pre-treated with 37% phosphoric acid (15 s for enamel and dentin), or 20% polyacrylic acid (15 s for enamel and dentin). Glass carbomer applied to the treated and non-treated surfaces. Conventional glass ionomer without any surface treatment served as a control.

Results: Enamel and dentin SBSs of the conventional glass ionomer cement were significantly higher than those of the glass carbomer material bonded to enamel and dentin without any surface treatments. Acid-etching and polyacrylic acid pre-treatments yielded similar enamel bond strength to that of glass ionomer cement. For dentin bonding, only polyacrylic acid pre-treatment improved SBS of glass carbomer to dentin surface.

Conclusions: Clinicians may consider the use of polyacrylic acid conditioner prior to the use of glass carbomer material.     

Impact of conditioning regimens and time on adhesion of a fiber post to root dentin using two resin cements

The aim of this study was to evaluate the influence of irrigation protocols on the bond strength of a glass fiber post bonded to dentin using two resin cements. In 200 root-filled teeth, post space was prepared and divided into five groups (n?=?40) based on the irrigation protocol: group 1 (3% sodium hypochlorite), group 2 (3% sodium hypochlorite – 17% Ethylene diamine tetraacetic acid), group 3 (a mixture of sodium hypochlorite and etidronic acid), group 4 (sodium hypochlorite – QMix), and group 5 (distilled water). Samples were subdivided into two subgroups (n?= 10) and fiber posts were cemented using subgroup A (Self-adhesive dual-cure resin cement; SEA) or B (dual-cure resin cement following an etch-and-rinse protocol, ER). Push-out bond strength was performed after 24 h and four months (n?= 10) and failure modes were categorized. Statistical analysis of data was carried out by appropriate analyses (p < 0.05). The irrigation protocol and the resin cement had a significant impact on push-out bond strength. Subgroup A group showed lower bond strength than B at both time periods when 3% NaOCl–17% EDTA and 1:1 mixture of 6% NaOCl + 18%EA protocols were used. Three percent NaOCl used in combination with 17% EDTA or QMix significantly decreased the push-out bond strength of ER at the end of four months (p < 0.05). In conclusion, dual-cure resin cements bonded with etch-and-rinse protocol showed highest bond strength when a mixture of NaOCl and etidronic acid was used as root canal irrigant. These values were differentially influenced by time.     

Evaluation of different desensitizing agents effect on shear bond strength of adhesive resin cement to dentin

Desensitizing agents can inhibit the bonding strength between dentin and adhesive resin cement. This study evaluated the effects of different desensitizing agents on the shear bond strength of adhesive resin cement to dentin. Sixty freshly extracted and caries free teeth were classified into five experimental groups, randomly (n?=?12). Each group was treated with a different desensitizing agent (Teethmate, Shield Force Plus, Admira Protect and Ultra-Ez) respectively, except for an untreated control group. After desensitizing agents and adhesive resin cement were applied to each dentin surface, all specimens were stored in incubator at 37?°C for 24?h. The shear bond strength was tested with a Universal testing machine at a 0.5?mm/min crosshead speed. Data were analysed by using a statistical software (SPSS 22). The results of the measurements were analysed by Kruskal Wallis test with Bonferroni correction and multiple comparisons were made by Wilcoxon test (p???.01). Specimens were examined by a scanning electron microscope, additionally. The Shield Force Plus showed significantly the highest shear bond strength compared with other groups (p?<?.01). Ultra-Ez showed the lowest shear bond strength (p?>?.01). There was no significant difference among Teethmate and Admira Protect groups (p?>?.01). Desensitizing agents containing resin monomers increased the bonding strength, however desensitizers containing calcium phosphate, potassium nitrate and fluoride did not effect the bonding strength of resin cement to dentin.     

Cyclic voltammetric studies on a monocrystalline antimony electrode

Monocrystalline antimony electrodes have been studied by cyclic voltammetry in solutions containing sodium nitrate and one of the following complexing agents: TRIS [Tris (hydroxymethyl) amino methane], orthophosphate, EDTA (ethylenedinitrilo tetraacetic acid) or tartrate at an ionic strength of 0.16 The results have been compared to results obtained in a solution containing only sodium nitrate, which has been shown previously to have no effect on the Sb-electrode potential in the pH range 2–10 which was studied.The results indicate formation of soluble complexes with the ligands studied. Competing reactions seem to take place in the solutions containing orthophosphate (and presumably EDTA). The reactions between Sb(III) and TRIS or orthophosphate seem to be reversible for all practical purposes.The complex formation between Sb(III) and TRIS seems to be weak since the behaviour of the electrode is very similar in TRIS and in pure nitrate solution. TRIS is therefore suitable as a buffer for calibrating antimony electrodes.     

XPS Characterization of Dentin and Dentin Treated with Bonding Conditioners

Samples of smear layer dentin prepared with #600 grit paper and treated with various conditioners (Gluma Conditioner, Scotchprep or Tenure Dentin Conditioner) were analyzed using XPS to determine the changes in surface composition as compared with controls of the smear layer or fractured dentin. Dentin treated with phosphoric acid liquid or gel was also analyzed. All of the conditioners lowered the Ca and P on the dentin. While phosphoric acid treated dentin exhibited similar reduction in Ca and P, Si was adsorbed onto the dentin when phosphoric acid etching gels were employed. Surface behavior diagrams were used to illustrate these changes. Micro ATR FTIR was used to confirm both the loss of Ca and P from the phosphoric-acid-etched dentin and the adsorption of the silica from the etching gel. These data are compared with other XPS studies of dentin conditioners and primers.     

Effect of Different Application Techniques of All-in-One Adhesives on Microtensile Bond Strength to Sound and Caries-Affected Dentin

The aim of this study was to evaluate the microtensile bond strength of two all-in-one self-etch adhesives applied to sound and caries-affected dentin with four different application techniques. Forty extracted third molars with occlusal caries were randomly divided into four groups for G-Aenial Bond and S3 Bond: (1) according to manufacturer's instructions; (2) with acid etching before applying adhesives; (3) doubling adhesive application time; and (4) doubling adhesive coating. Teeth were sectioned to obtain 1-mm- ± 0.2-mm-thick dentin sticks and subjected to a tensile force. For G-Aenial Bond, doubling the time and application of two consecutive coats produced significantly higher strength than that obtained by following manufacturers' instructions and acid etching application to sound dentin. Prior acid etching and application of two consecutive coats to caries-affected dentin generated significantly higher bond strength than that using other techniques. For S3 Bond, there was no significant difference between application techniques in caries-affected dentin. For sound dentin, double-time application of S3 Bond produced significantly higher strength than application according to the manufacturers' instructions. Compared to the application according to manufacturer's instructions, acid etching before applying adhesives, doubling application time, and doubling the coating had a positive effect on bond strength to caries-affected dentin for all-in-one adhesives.     

Which is effective on bond strength of resin-based sealers: incorporation of powdered dentin to primer or adhesive?

The aim of this study was to investigate the effect of adding powdered dentin to primer or adhesive in a self-etch system on the shear bond strength of three resin-based sealers. Seventy-two premolars were sectioned buccolingually, and 144 root halves were divided into three groups according to the sealer used: epoxy resin-based sealer (AH Plus), methacrylate resin-based (RealSeal, Hybrid Root SEAL) n = 48. The surfaces were irrigated with 5% NaOCl, 17% EDTA, distilled water for 5 min. Four subgroups were created (n = 12): control group; Clearfil Liner Bond 2 V treated group; powdered dentin added to the primer of Clearfil Liner Bond 2 V (40 wt.%); and powdered dentin added to the adhesive of Clearfil Liner Bond 2 V (20 wt.%). Dentin powder was prepared. Three mm high buildups with a constant surface area of 3.45 mm² were created using the sealers and allowed to set (37 ºC, 100% humid, 72 h). The samples were tested to failure for shear bond strength (1 mm/min). The data were calculated (MPa) and analyzed using two-way ANOVA, one-way ANOVA, and Tukey HSD tests. Adhesive use decreased the bonding performance of AH Plus (p = 0.00). Mean bond strength of the other sealers was found similar to control. Primer or adhesive resin with powdered dentin did not increase the adhesive performance of the self-etch system used. The shear bond strength of RealSeal was significantly increased when powdered dentin was added to primer or adhesive (p = 0.00). The effect of adding powdered-dentine to primer or adhesive in a self-etch system on the shear bond strength was sealer-dependent .     

转晶剂与蒸压参数对磷石膏制备α半水石膏的影响

以经盐溶液预处理的磷石膏为原料,以乙二胺四乙酸（EDTA）和顺丁烯二酸酐为复合转晶剂,采用蒸压法制备α半水石膏。借助扫描电镜（SEM）、X射线衍射（XRD）分析研究了复合转晶剂掺量、pH、蒸压温度对生成α半水石膏的晶体形貌、物相组成的影响。研究结果表明,复合转晶剂中EDTA的最佳掺量（质量分数）为0.4%、顺丁烯二酸酐的最佳掺量（质量分数）为0.3%,溶液最佳pH为7.5,最佳蒸压温度为140 ℃。在此条件下制得的α半水石膏结晶形态最好,呈短柱状,长径比接近1∶1。     

The effects of chelation on the adhesion of two different root canal sealers

Objective: This study aims to evaluate alterations in the root canal dentin after irrigation with EDTA, HEBP, and Chitosan in order to determine the push-out bond strengths of the different root canal sealers on altered dentin surfaces. Materials And Methods: Crowns of 70 maxillary single-rooted teeth were removed to obtain a standardized length of 16 mm. The canals were instrumented using rotary files and the step back technique. The master apical file used in this study was #40. The subgroups were determined based on the chelation agent and the material of the root canal sealer that was used (17% EDTA, 18% HEPB, 0.2% Chitosan, Well Root ST (WRST) or AH Plus). Three slices with 1 mm thickness were cut from the root thirds of each tooth and subjected to a push-out test. The data (MPa) were analyzed using a one-way ANOVA and a Duncan’s multiple comparison test at a level of α = 0.05. Finally, scanning electron microscope (SEM) photographs were taken. Results: Groups that used WRST exhibited significantly higher push-out bond strength values in all subgroups independent of the irrigant that was used (ANOVA, p < 0.05). Group 1 showed higher push-out bond strength than the other AH Plus subgroups. Conclusion: The EDTA improved the push-out bond strength of the AH Plus. The WRST root canal sealer had the highest push-out bond strength and did not depend on the irrigant used.     

Alpha-hydroxy glycolic acid for root dentin etching: Morphological analysis and push out bond strength

The purpose of this study was investigated the use of α-hydroxy glycolic acid as a dentin etchant for adhesive procedures in the root canal. The etching pattern of glycolic acid and mineral content distribution of root canal dentin were assessed by scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS), respectively. The effect of glycolic acid surface etching on the push out bond strength of fiber post to root dentin was assessed using three adhesive systems: Single Bond Universal [SBU], Scotchbond Multipurpose [SBMP], and Ambar [AM]. The 37% phosphoric acid was used as a control group. The bond strength values were statistically compared using ANOVA/Fisher LSD tests (α = 0.05). SEM revealed similar etching patterns for phosphoric acid and glycolic acid. Both acids also shared similar interfacial morphology of the hybrid layer. EDS showed similar levels of Ca and Mg after treatment with glycolic acid when compared with phosphoric acid. When the P level was compared, it was observed that phosphoric acid caused greater removal of P. The push out bond strengths were statistically similar between glycolic acid and phosphoric acid in all groups (p > 0.05). Comparisons using post hoc Fisher LSD test showed that the bond strengths in the SBU and SBMP groups were not significantly different from each other (p > 0.05). The bond strength in the AM group was similar to that in the SBMP group (p > 0.05); however, it was significantly lower than that in the SBU group (p < 0.05). It can be concluded that the glycolic acid effectively etched root dentin surfaces, resulting in a surface pattern, hybrid layer, and push out bond strength similar to those produced by traditional phosphoric acid. Therefore, glycolic acid may be recommended as a suitable root dentin surface etchant for adhesive restorative procedures.     

Atmospheric plasma treatment of CFRP composites to enhance structural bonding investigated using surface analytical techniques

This paper considers the effects of an atmospheric plasma treatment (APT) on the surface properties of an amine cured carbon fibre/epoxy resin composite, and how those effects manifest over time. In particular, the ability of the APT to remove a thin layer of silicone-containing, proprietary, release agent (Chemlease^® 41 EZ), typically used in the production of composite components, has been investigated. It was concluded that the reduction in water contact angle (WCA) after APT for both the solvent wiped and contaminated surfaces was as a result of an increase in oxygen containing species at the surface, as determined through X-ray photoelectron spectroscopy (XPS). Further, it was found that the APT slightly reduced the failure strength of lap shear specimens for solvent wiped surfaces, whereas an increase in failure strength was observed for silicone contaminated samples. WCA and XPS results suggest that the contaminant layer was not removed, but instead transformed to a more stable inorganic form.     

The effect of chelation on the selective transport of alkaline earth metal ions in asymmetric cellulose acetate hyperfiltration membranes. II

The effects of chelation on the transport of calcium and magnesium, both separately and in a variety of admixtures, in a controlled series of asymmetric cellulose acetate membranes were characterized. Ethylenediaminetetraacetic acid (EDTA) and ethylenebis(oxyethylenenitrilo)tetraacetic acid (EGTA) were used as chelating agents for the alkaline earth metal ions. Asymmetric cellulose acetate membranes annealed at 70°, 75°, and 85°C were studied. Chelation of each of these alkaline earth metals ions in aqueous solutions at pH 6, by either EDTA or EGTA, significantly increased the overall hyperfiltration rejections of these metals by all the membranes studied. The increase in rejection varied montonically with the fraction of metal ion complexed. The higher rejection of metal chelates, compared to the rejection of unbound metal ions, was considered to be the result of the significantly larger size of the chelated species. Calculations suggested that selective (or competitive) chelation took place at pH 6 in a mixture of calcium and magnesium ions in the presence of a stoichiometrically limiting amount of chelating agent. Calcium successfully competed for most of the available chelating agent in equimolar aqueous solutions of chelating agent, calcium, and magnesium. The calcium rejection was explained primarily in terms of the effects of chelation per se on the effective size of the formed complex even in feeds comprised of these ternary solute mixtures. The complexation reaction between magnesium and EGTA is, however, so unfavorable at pH 6 that the Mg²⁺ ion remains uncomplexed even in the presence of an equivalent amount of EGTA. The observed increased rejection of magnesium ions, therefore, in ternary systems was explained by electroneutrality criteria and by solute–membrane interactions involving the various calcium species and the membranes.