One-step Self-etch Adhesives Research Articles

Evaluation of the adaptation of dental polymers using cross-polarization optical coherence tomography

Objective: The purpose of this study was to image gap formation and micro-leakage in restored cervical cavities with three different dental adhesives using cross-polarization optical coherence tomography (CP-OCT). Methodology: Thirty saucer shape class-V cavities were prepared on the buccal and lingual surfaces of extracted human molars. Samples were randomly divided into three groups (n = 10) according to the used adhesive; all-in-one Tetric N-Bond self-etch (TN; Ivoclar/Vivadent, Liechtenstein), G-Premio universal (GP; GC, Japan) in self-etch mode and two-step self-etch Clearfil SE Bond 2 (SE; Kuraray Noritake, Japan). All cavities were bonded and filled with a universal composite (Estelite ∑ Quick, Tokuyama Dental, Japan) and cured by the LED light curing unit. Then, tomographic images were taken under CP-OCT to detect gap formation at the cavity in order to calculate the gap percentage in each group. Result: Mann-Whitney U test showed statistical significant difference among all groups (p < 0.05) with high gap percentage in GP group followed by TN group. SE group showed the highest composite adaptation with the lowest gap percentage. Conclusion: Within the limitation of the study, the restored cavities with two-step self-etch adhesive exhibited fewer microgaps and micro-leakage than one-step self-etch adhesives.

Effects of the Contents of Various Solvents in One-step Self-etch Adhesives on Shear Bond Strengths to Enamel and Dentin

The aim of this study was to evaluate the shear bond strengths (SBSs) of one-step self-etch adhesives containing different co-solvents to enamel and dentin and to determine the failure modes of tested specimens. Two hundred and forty (n = 240) sound human molars were used. The buccal surfaces of each tooth were ground and polished to obtain flat enamel surfaces (n = 120) or to expose the underlying dentin (n = 120). The specimens with exposed enamel or dentin were randomly divided into four main groups (n = 30) according to the one-step self-etch adhesives used: Bond-1 SF, OptiBond All-In-One, G-aenial, and Single Bond Universal adhesive. All the main groups were then subdivided into two subgroups (control and thermocycling subgroups) (n = 15). After bonding procedures, a composite restoration (Filtek Z250) was applied in a vinyl tube and condensed against the cured adhesive bonding agent, to form a resin cylinder. The specimens were stored in distilled water at 37°C for 24 hours (control and thermocycling subgroups), followed by thermocycling (5-55°C/5,000 cycles + storage in artificial saliva for 2 weeks) (thermocycling subgroup). They were subjected to SBS testing in a universal testing machine at a crosshead speed of 0.5 mm/minute. After being shear-tested, all fractured samples were examined by means of a Hirox Digital Microscope at 50× magnification for failure analysis. The data were analyzed by one-way analysis of variance followed by Tukey's post hoc analysis at a p value of ≤0.05. OptiBond All-In-One adhesive showed significantly higher mean SBS values on both types of tooth structures (enamel and dentin) and under different conditions (control and thermocycled) compared with the other three adhesives (p < 0.001), except in the enamel-thermocycled group, where the Single Bond Universal adhesive showed higher mean SBS but without a significant difference compared with the OptiBond All-In-One adhesive (p = 0.266), and there was no significant difference between OptiBond All-In-One and G-aenial Bond in the same group (p = 0.192). Conversely, Bond-1 SF showed significantly lower mean SBS values compared with those of the other three adhesives on different types of tooth structures and under different conditions (control and thermocycled) (p < 0.001). One-step self-etch adhesives containing ethanol as a solvent or co-solvent showed higher SBS compared with the other self-etching bonding agents. The bond strength values of these adhesives to dentin are significantly higher than those to enamel. The types of solvents of one-step self-etch adhesives had an effect on SBS, and the absence of solvent in those adhesives would adversely influence their performance. How to cite this article: Ageel FA, Alqahtani MQ. Effects of the Contents of Various Solvents in One-step Self-etch Adhesives on Shear Bond Strengths to Enamel and Dentin. J Contemp Dent Pract 2019;20(11):1260-1268.

Adhesion of dual-polymerized luting cement on superficial and deep dentin using different one-step self-etch mild adhesive systems

This study evaluated adhesion of dual-polymerized resin cement to superficial dentin (SD) and deep dentin (DD) using one-step self-etch adhesives at varying pH. After smear layer was created on third molars (N = 60, n = 15 per group), adhesive resins, 1- Clearfil S3 Bond Plus-CBP (Kuraray) (pH: 2.3), 2- Bisco All Bond Universal-BAU (Bisco) (pH: 3.2), 3- Single Bond Universal Adhesive-SBU (3M ESPE) (pH: 2.7), 4- Nova Compo-B Plus-NCBP (Imicryl) (pH: 2.5–3), were applied on SD and DD. Resin cement (Variolink II, Ivoclar Vivadent) was adhered incrementally on the SD surfaces using polyethylene molds and photo-polymerized for 40 s from 5 directions (output: 1200 mw/cm2). After macroshear and microshear test, in order to achieve DD specimens, SD were removed 1 mm in the pulp direction and the same bonding and test procedures were performed. The specimens were kept at 37 °C for 24 h. The adhesion tests were conducted in the Universal Testing Machine and failure types were analyzed. The data were analyzed using Univariate ANOVA, Tukey`s, Kruskal-Wallis and Mann-Whitney tests (α = .05). Test method, dentin level and the adhesive resin significantly affected the results (MPa) (p < .05). After macroshear test, more incidences of cohesive failures in DD were observed with NCBP Plus. On SD, NCBP presented the highest results followed by BAU using macroshear test. On DD, NCBP presented the highest results followed by SBU. Not only the pH but the chemical composition affected adhesion especially to SD while in DD, the difference between the adhesive resins was less significant.

Effect of anaerobic cure of self-etch adhesive on degree of conversion and shear bond strength

The main aim was to evaluate the effect of postponing the curing of the adhesive layer until the first layer of composite resin is applied-hereby oxygen-inhibited layer (OIL) formation and its detrimental effect on the degree of conversion (DC) of self-etch adhesives should be prevented. For this purpose, the degree of conversion and shear bond strength of four current market self-etch adhesives were evaluated, assessing the effect of curing the adhesives anaerobically and then under two different thicknesses of composite resin, and compare this to the samples cured alone and in air. The degrees of conversion were obtained by attenuated total reflectance-Fourier transform infrared (ATR-FTIR) spectroscopy, after the samples were prepared on a glass slide. The samples were either light-cured in air or anaerobically under a clear matrix strip alone, under 2mm of cured composite resin or under 4mm of cured composite resin. To determine the shear bond strength (SBS), extracted molars were halved and set in acrylic. Prefabricated cured cylinders of composite resin (TPH 3, 2.4mm in diameter) of two different lengths are placed over the adhesives under the following conditions: light-cured conventionally (2-mm-long cylinder) and light-cured anaerobically under the uncured end of the piece of composite resin (using both 2- and 4-mm-long cylinders as separate treatments). After another incubation for 24h at 37°C, the samples were subjected to shearing using the Bisco Shear Bond Strength Tester. The degree of conversion of the one-step self-etch adhesives was not statistically different when cured anaerobically under a clear matrix strip or cured anaerobically under 2mm of composite resin. These results were greater than those cured under 4mm. Shear bond strength between samples cured in air and anaerobically were similar under 2mm of composite resin tubes, while those cured anaerobically under 4mm of resin showed lower shear bond strength. When cured anaerobically, one-step self-etch adhesives show a greater degree of conversion and no significant difference in degree of conversion and shear bond strength when compared to those cured in air under the same thickness of composite resin. The results obtained from DC and SBS analysis show promise in placing the uncured adhesive under the composite resin and curing both the adhesive and restoration material simultaneously.

Effect of Trypsin/EDTA Conditioning on Marginal Microleakage of Class V Composite Restorations Bonded With a One-Step Selfetch Adhesive

Background: Sodium hypochlorite and EDTA solutions are used in the preparation of dentin surfaces, which may increase the bond strength of the composite restorations and decrease their microleakage scores. This in-vitro experimental study aimed to assess the effect of dentin surface conditioning with EDTA/trypsin solution prior to bonding procedure with Clearfil S3 Bond on the microleakage of class V composite restorations. Methods: Class V cavities were prepared on the buccal and lingual surfaces of 18 human premolars (n=18) and randomly assigned into two groups. In the control group, Clearfil S3 Bond was applied on the dentin surfaces. While in the experimental group, before applying Clearfil S3 Bond, the surfaces were conditioned with EDTA/trypsin solution. The cavities on the teeth were then incrementally filled with Filtek Z250 light-cure composite. Afterward, all the samples were thermocycled for 500 cycles. Next, the specimens were immersed in methylene blue solution for 72 hours. The restorations were sectioned buccolingually through the center of the restorations with a diamond disk. Then, microleakage at the tooth- restoration interface was evaluated in the enamel and dentin margins blindly using dye penetration under a stereomicroscope at ×40 magnification. Finally, data were statistically analyzed by Mann-Whitney U test. Results: The results showed no significant differences between two groups regarding the microleakage scores of the enamel and dentin edges. In addition, in all sections and edges of the experimental group, decreased microleakage scores were attained compared to the control specimens (P<0.03). Conclusions: Regarding the limitations of the present study, the preparation of dentin surfaces with EDTA/trypsin solution before applying Clearfil S3 Bond resulted in the decreased microleakage scores compared to unprepared surfaces.

Optical Evaluation of Enamel Microleakage with One-Step Self-Etch Adhesives.

In this in vitro study, cross-polarization optical coherence tomography (CP-OCT) was used to evaluate microleakage in dental composite restorations bonded to enamel with two types of one-step self-etching (SE) adhesives. One-step SE adhesives were proposed to simplify bonding of composite restorations. However, bonding of these simplified adhesive to dental enamel is still questionable. OCT is a promising diagnostic tool that allows micron-scale imaging of biological tissues and structures. Class-V cavities (4-mm diameter × 1-mm depth) were prepared on the labial surfaces of extracted human anterior teeth with margins and floor located in enamel. The cavities were then divided into two groups (n = 5) and restored with either Tetric N-Bond Universal (Ivoclar Vivadent, Liechtenstein) or Palfique Bond (Tokuyama Dental Corporation, Japan), followed by Estelite Flow Quick flowable composite (Tokuyama Dental Corporation). After storage in 100% humidity for 24 h, specimens were immersed in ammoniacal silver nitrate solution for another 24 h. Later, they were rinsed and immersed in photo-developing solution under fluorescent light for 8 h. CP-OCT at 1310 nm center wavelength was used to scan seven two-dimensional cross-sectional images from each specimen. Each cross-sectional image was analyzed using ImageJ software to quantify interfacial microleakage at the cavity floor. Student's t-test showed significant difference between the tested adhesives (p < 0.05). Palfique Bond adhesive presented inferior interfacial adaptation as it obtained higher values of floor microleakage compared to Tetric N-Bond Universal adhesive group. CP-OCT enabled nondestructive quantitative assessment of microleakage in enamel dental restorations.

Effect of Surface Sealant Reapplication on Clinical Performance of HEMA-containing and HEMA-free Self-etch Adhesives: Two-year Results.

To evaluate the clinical performance of one-step self-etch adhesives over two years with and without the application of a surface sealant. In total, 160 restorations in 40 patients were performed for occlusal caries. Each patient received four Class I restorations, which included a 2-hydroxyethyl methacrylate (HEMA)-containing (Clearfil S3 Bond) and HEMA-free (G-aenial Bond) one-step self-etch adhesive system with and without surface sealant. Half of the restored teeth received Fortify Plus (Bisco) surface sealant material, and the other half were polished with Sof-Lex discs only. Two experienced calibrated examiners clinically evaluated the restorations at baseline and at one- and two-year recalls according to the modified US Public Health Service criteria. The filled surface sealant material was reapplied at each evaluation period. After two years, none of the restorations had failed. There were no significant differences between the two dentin adhesives with or without a surface sealant application among the evaluation periods. Each dentin adhesive with and without surface sealant showed significant changes from the clinically ideal (Alfa) to clinically acceptable (Bravo) with regard to marginal discoloration, marginal adaptation, and surface texture. Sealed restorations exhibited lower ideal restoration rates with regard to color matching and surface texture and higher ideal restoration rates with respect to marginal adaptation compared with unsealed restorations. In addition, the surface sealant application reduced the marginal discoloration of the HEMA-free one-step self-etch adhesive. The two-year success rates of HEMA-containing and HEMA-free self-etch adhesives with and without surface sealing application were excellent. Although the surface sealant application was not effective with regard to changes in color matching and surface texture, it improved the marginal adaptation of the dentin adhesive and the marginal discoloration of a HEMA-free adhesive.

Clinical Effectiveness of a Resin-modified Glass Ionomer Cement and a Mild One-step Self-etch Adhesive Applied Actively and Passively in Noncarious Cervical Lesions: An 18-Month Clinical Trial

To evaluate the clinical effectiveness of two methods of application of a mild one-step self-etch adhesive and composite resin as compared with a resin-modified glass ionomer cement (RMGIC) control restoration in noncarious cervical lesions (NCCLs). A total of 294 restorations were placed in 56 patients, 98 in each one of the following groups: 1) G-Bond active application combined with Solare-X composite resin (A-1SEA), 2) G-Bond passive application combined with Solare-X composite resin (P-1SEA), and 3) GC II LC RMGIC. The restorations were evaluated at baseline and after six, 12, and 18 months according to the FDI criteria for fractures/retention, marginal adaptation, marginal staining, postoperative sensitivity, and secondary caries. Cumulative failure rates were calculated for each criterion at each recall period. The effect of adhesive, method of application, and recall period were assessed. The Kruskal-Wallis test for intergroup comparison and Friedman and Wilcoxon signed ranks tests for intragroup comparison were used for each criterion ( α=0.05). The retention rates at 18 months were 93.26% for the A-1SEA group, 86.21% for the P-1SEA group, and 90.91% for the RMGIC group. The active application improved the retention rates compared with the passive application of mild one-step self-etch adhesive; however, no statistically significant difference was observed between the groups. Marginal staining was observed in 13 restorations (1 in A-1SEA, 4 in P-1SEA, and 8 in RMGIC) with no significant difference between the groups. The RMGIC group showed a significant increase in marginal staining at 12 and 18 months from the baseline. There was no significant difference between the groups for marginal adaptation, secondary caries, or postoperative sensitivity. Within the limitations of the study, we can conclude that mild one-step self-etch adhesive followed by a resin composite restoration can be an alternative to RMGIC with similar retention and improved esthetics in restoration of NCCLs. Agitation could possibly benefit the clinical performance of mild one-step self-etch adhesives, but this study did not confirm that the observed benefit was statistically significant.

The effect of warm air-blowing on the microtensile bond strength of one-step self-etch adhesives to root canal dentin

PurposeThe use of warm air-blowing to evaporate solvents of one-step self-etch adhesive systems (1-SEAs) has been reported to be a useful method. The purpose of this study was to evaluate the effect of warm air-blowing on root canal dentin. MethodsFour 1-SEAs (Clearfil Bond SE ONE, Unifil Core EM self-etch bond, Estelink, BeautiDualbond EX) were used. Each 1-SEA was applied to root canal dentin according to the manufacturers’ instructions. After the adhesives were applied, solvent was evaporated using either normal air (23±1°C) or warm air (80±1°C) for 20s, and resin composite was placed in the post spaces. The air from the dryer, which could be used in normal- or hot-air-mode, was applied at a distance of 5cm above the root canal cavity in the direction of tooth axis. The temperature of the stream of air from the dryer in the hot-air-mode was 80±1°C, and in the normal mode, 23±1°C. After water storage of the specimens for 24h, the μTBS were evaluated at the coronal and apical regions. The μTBSs were statistically analyzed using three-way ANOVA and Student’s t-test with Bonferroni correction (α=0.05). ResultsThe warm air-blowing significantly increased the μTBS of all 1-SEAs at the apical regions, and also significantly increased the μTBS of two adhesives (Estelink and BeautiDualBond EX) at coronal regions. ConclusionsThe μTBS of 1-SEAs to root canal dentin was improved by using warm air-blowing.

Bonding effectiveness of experimental one-step self-etch adhesives to sound and caries-affected dentin

Experimental one-step, self-etch adhesives containing different contents of an acidic methacrylate monomer (GDMA-P) were formulated and their effectiveness in bonding to sound dentin (SoD) or caries-affected dentin (CAD) was investigated. The CAD was obtained using a microcosm biofilm model. HEMA-based adhesives were formulated with 5, 20, or 35 wt% of GDMA-P (AD5, AD20, AD35), with pH ranging between 1.05 ± 0.05 and 1.93 ± 0.15. Shear bond strength to dentin was assessed after storage for 24 h or 6 months. Morphology of the bonded interfaces was observed using SEM. The exposed collagen area at bonded interfaces was measured using a histological staining technique. Degree of C=C conversion within the hybrid layer, measured by micro-Raman spectroscopy, indicated that AD35 had lower in situ C=C conversion than the other adhesives. A more evident exposed collagen zone along the base of the hybrid layer was observed in CAD samples. The hybrid layer was generally thicker in CAD. AD20 had the highest in situ C=C conversion and yielded stable bond strengths that were generally independent of the dentin condition. Additionally, the bonding effectiveness was dependent on adhesive acidity, type of dentin bonding substrate, and water storage time.

Bonding effectiveness of self-etch adhesives to dentin after 24 h water storage.

Purpose:This study evaluated the immediate bonding effectiveness of five self-etch adhesive systems bonded to dentin.Materials and Methods:The microtensile bond strength of five self-etch adhesives systems, including one two-step and four one-step self-etch adhesives to dentin, was measured. Human third molars had their superficial dentin surface exposed, after which a standardized smear layer was produced using a medium-grit diamond bur. The selected adhesives were applied according to their respective manufacturer's instructions for μTBS measurement after storage in water at 37°C for 24 h.Results:The μTBS varied from 11.1 to 44.3 MPa; the highest bond strength was obtained with the two-step self-etch adhesive Clearfil SE Bond and the lowest with the one-step self-etch adhesive Adper Prompt L-Pop. Pretesting failures mainly occurring during sectioning with the slow-speed diamond saw were observed only with the one-step self-etch adhesive Adper Prompt L-Pop (4 out of 18).Conclusions:When bonded to dentin, the self-etch adhesives with simplified application procedures (one-step self-etch adhesives) still underperform as compared to the two-step self-etch adhesive Clearfil SE Bond.

Shear bond strength of one-step self-etch adhesives to dentin: Evaluation of NaOCl pretreatment.

BackgroundThe aim of this study was to evaluate the influence of dentin pretreatment with NaOCl on shear bond strength of four one-step self-etch adhesives with different pH values.Material and MethodsBovine permanent incisors were used. Four one-step self-etch adhesives were tested: Adper™ Easy Bond, Futurabond NR, G-aenial Bond, Clearfil S3 Bond. One two-step self-etch adhesive (Clearfil SE Bond) was used as control. Group 1- no pretreatment; group 2- pretratment with 5,25 % NaOCl; group 3- pretreatment with 37 % H3PO4 etching and 5,25 % NaOCl. A hybrid composite resin was inserted into the dentin surface. The specimens were tested in a universal testing machine. The examiners evaluated the fractured surfaces in optical microscope to determine failure modes, quantified with adhesive remnant index (ARI).ResultsDentin pretreatment variably influenced bond strength values of the different adhesive systems. When no dentin pretreatment was applied, no significant differences were found (P >.05) among four adhesives tested. No significant differences were recorded when comparing NaOCl pretreatment with H3PO4 + NaOCl pretreatment for all adhesive tested (P >.05) except Clearfil S3 Bond that showed higher shear bond strength values when H3PO4 was applied. Frequencies of ARI scores were calculated.ConclusionsThe influence of dentin pretreatment with NaOCl depends on the composition of each adhesive system used. There was no difference in bond strength values among self-etch adhesives with different pH values. Key words:Dentin, pretreatment, self-etch adhesives.

Are self-etch adhesives reliable for primary tooth dentin? A systematic review and meta-analysis.

The purpose of this study was to systematically evaluate the dentin bond strength of etch-and-rinse and self-etch adhesives to primary teeth. In this study, PubMed, ISI (all databases), Scopus, and Cochrane Database were searched according to the selected keywords up to May 11, 2016. The full texts of published articles that appeared to meet the primary criteria for inclusion in this study were obtained. Due to the variation in the methods used, the studies were divided into 2 groups: Group 1 – studies that evaluated the micro-tensile bond strengths (MTBSs) of two-step etch-and-rinse adhesives and two-step self-etch adhesives and Group 2 – studies that evaluated the MTBSs of two-step etch-and-rinse adhesives and one-step self-etch adhesives. The initial search yielded 1447 publications. After a methodological assessment, 8 publications were selected. The results of this study showed that the MTBS of the etch-and-rinse adhesives and the two-step self-etch adhesives were similar (P = 0.34), and both were significantly higher than that of the one-step self-etch adhesive (P = 0.001). This meta-analysis showed that the application of two-step self-etch adhesives performs well when used for primary dentin and can be used to save time in pediatric dentistry.

Nine-year Clinical Performance of a HEMA-free One-step Self-etch Adhesive in Noncarious Cervical Lesions.

One-step self-etch adhesives are among the most popular adhesives to directly bond composite to tooth tissue, mainly because of their perceived ease-of-use. The aim of this randomized controlled trial was to evaluate the clinical performance of a HEMA-free 1-step self-etch adhesive (1SEa), as compared with a 3-step etch-and-rinse adhesive (3E&Ra). 267 non-carious cervical lesions in 52 patients were restored with a microhybrid composite Gradia Direct (GC), bonded in random order either with the HEMA-free 1SEa G-Bond (GB; GC) or the considered gold-standard 3E&Ra Optibond FL (OFL; Kerr). The restorations were evaluated after 6 months, 1, 2, 3, 5 and 9 years of clinical service for retention, marginal adaptation, marginal discoloration, caries occurrence and tooth sensitivity. Statistical analysis was done using a logistic regression model with generalized estimating equations (2-way GEE model). The patient recall rate at 9 years was 82.6%. The overall clinical success rate was 80.3% and 79.5% for GB and OFL, respectively. In total, 47 restorations (23 GB, 24 OFL) failed because of retention loss, severe marginal defects and/or discoloration and/or caries. A similar retention rate of 89.7% was recorded for both adhesives GB and OFL. Slight marginal defects and superficial marginal discoloration, though both still clinically acceptable, were significantly more observed at the incisal enamel side of GB (92.4% and 52.1%, respectively) than OFL (59.6%; 30.8%) restorations (p < 0.05). After 9 years of clinical service, class-V restorations bonded with the HEMA-free 1SEa performed clinically equally successful as those bonded with the 3E&Ra. However, more marginal deterioration, though still clinically acceptable, was recorded at the incisal enamel side for the 1SEa.

Smear layer-deproteinizing improves bonding of one-step self-etch adhesives to dentin

ObjectivesSmear layer deproteinizing was proved to reduce the organic phase of smear layer covered on dentin surface. It was shown to eliminate hybridized smear layer and nanoleakage expression in resin–dentin bonding interface of two-step self-etch adhesive. This study aimed to investigate those effects on various one-step self-etch adhesives. MethodsFour different one-step self-etch adhesives were used in this study; SE One (SE), Scotchbond™ Universal (SU), BeautiBond Multi (BB), and Bond Force (BF). Flat human dentin surfaces with standardized smear layer were prepared. Smear layer deproteinizing was carried out by the application of 50ppm hypochlorous acid (HOCl) on dentin surface for 15s followed by Accel® (p-toluenesulfinic acid salt) for 5s prior to adhesive application. No surface pretreatment was used as control. Microtensile bond strength (μTBS) and nanoleakage under TEM observation were investigated. The data were analyzed by two-way ANOVA and Tukey’s post-hoc test and t-test at the significant level of 0.05. ResultsSmear layer deproteinizing significantly improved μTBS of SE, SU, and BB (p<0.001). Hybridized smear layer observed in control groups of SE, BB, and BF, and reticular nanoleakage presented throughout the hybridized complex in control groups of BB and BF were eliminated upon the smear layer deproteinizing. SignificanceSmear layer deproteinizing by HOCl and Accel® application could enhance the quality of dentin for bonding to one-step self-etch adhesives, resulting in the improving μTBS, eliminating hybridized smear layer and preventing reticular nanoleakage formation in resin–dentin bonding interface.

Bond Strength Comparison of One-Step/Two-Step Self-Etch Adhesives to Cavity Floor Dentin after 2.5 Years Storage in Water

In recent years, decrease in dentin bond strength of one-step self-etch adhesives after long-term water storage has been reported; however, the flat dentin surface of the extracted tooth has been used to carry out the bond strength tests in the majority of the previous studies. Objectives: The purpose of this study was to compare the micro-tensile-bond-strength (μTBS) of three one-step self-etch adhesives and a two-step self-etch adhesive on the cavity floor dentin after 2.5 years storage in distilled water. Materials and Methods: Adhesives were used in this study: three one-step self-etch adhesives (Primefil, GBOND PLUS and Beauti Bond), and one two-step self-etch adhesive (Clearfil SE Bond), which was used as the control. Bowl-shaped cavities of extracted human incisors were treated with each adhesive and filled with each flowable resin composite from the same manufacturer. The specimens were stored in distilled water at room temperature for two and a half years. The beam samples were made and subjected to μTBS test using the tabletopmaterial- tester. The data were statistically analyzed using one-way ANOVA. Results: The μTBS value of G-BOND PLUS was higher than that of other adhesives; however, the results of ANOVA showed no significant differences in μTBS values among all adhesives. Conclusion: There was no significant difference between one-step and two-step on the bond strength of selfetch adhesives to the cavity dentin floor after a storage period of 2.5 year.

Dentin bonding performance of experimental one-step adhesives after incorporation of POOH–SiO2 nanoparticles

This study investigated the effect of adding different concentrations of phosphate-grafted-silica nanoparticles (SiO2–POOH) on dentin bond strength of experimental one-step self-etching adhesives (1-SEAs). Phosphate functional group was grafted onto silica nanoparticles through the free radical polymerization of an acid phosphate monomer [methacryloyloxyethyl dihydrogen phosphate/bis (methacryloyloxyethyl) hydrogen phosphate—HEMA-P] in an alcoholic medium. The resulting SiO2–POOH was characterized by FTIR spectroscopy. 1-SEA with two different acidic phosphate monomer concentrations (HEMA-P at 0 and 40% wt) were prepared and SiO2–POOH was added in 0 (control), 0.1, 0.2, 0.5, 1, 2, 4, 6 and 8wt%. The formulated 1-SEAs were evaluated for shear bond strength to dentin. Statistical comparisons were conducted at 5% significance level. The grafting reaction of SiO2–POOH was confirmed by FTIR. Compared with the unfilled 1-SEA, the addition of 0.1wt% of SiO2–POOH nanoparticles resulted in a significant dentin bond strength increase for HEMA-P40% concentration (p ≤ 0.001) while the addition of higher concentration of SiO2–POOH (0.2, 0.5, 1, 2, 4, 6 and 8wt%) reduced significantly the bond strength. The 1-SEA formulated without an acidic monomer (HEMA-P0%) did not exhibit bonding to the dentin, irrespective of SiO2–POOH concentration added. SiO2–POOH nanoparticles were obtained through graft polymerization of acidic phosphate monomer with silanized SiO2 nanoparticles. The addition of the 0.1wt% of SiO2–POOH nanoparticles associated with acidic monomer to 1-SEA improves the bonding effectiveness.

Marginal integrity of low-shrinking versus methacrylate-based composite: effect of different one-step self-etch adhesives.

The aim of the study was to evaluate the influence of composite type and adhesive system on the quality of marginal adaptation in standardized Class V cavities before and after thermo-mechanical loading (TML). The cavities were restored using different combinations of three adhesive systems [(Silorane System Adhesive (SSA), Clearfil S3 Bond (S3), G-Bond (G-B)] and two resin composite materials (Filtek Silorane, Clearfil AP-X). Six groups (n=10): Group A (SSA-Primer+SSA-Bond, Filtek Silorane), Group B (SSA-Primer+SSA-Bond, Clearfil AP-X), Group C (S3+SSA-Bond, Filtek Silorane), Group D (S3+SSA-Bond, Clearfil AP-X), Group E (G-B+SSA-Bond, Filtek Silorane) and Group F (G-B+SSA-Bond, Clearfil AP-X) were defined. Marginal adaptation was assessed on replicas in the SEM at 200×magnification before and after TML (3000×5-55°C, 1.2 106×49N; 1.7Hz) under simulated dentinal fluid. The highest scores of continuous margins (%CM) were observed in the group F (G-B+SSA-Bond, Clearfil AP-X: before loading 96.4 (±3.2)/after loading 90.8 (±7.0)). A significant effect of adhesive system, composite type and loading interval was observed on the results (p<0.05). Significantly lower scores of %CM were observed for silorane-based composite (Filtek Silorane) after TML in comparison with methacrylate-based composite (Clearfil AP-X) considering total marginal length (p<0.05). For both Filtek Silorane and Clearfil AP-X, G-Bond performed significantly better than SSA-Primer and Clearfil S3 Bond (p<0.05). For all combinations of one-step self-etch adhesives and SSA-Bond resin coating, silorane-based low-shrinking composite exhibited inferior marginal adaptation than did the methacrylate-based composite.

Layering mechanism of MDP-Ca salt produced in demineralization of enamel and dentin apatite

ObjectiveThe 10-methacryloyloxydecyl dihydrogen phosphate (MDP) (EX adhesives)-based one-step self-etch adhesives have become widely utilized due to their simplified application procedures. The aim of this study was to determine the type of the molecular species of calcium salts of MDP (MDP-Ca salts) that form a layered structure and to understand the layering mechanism of MDP-Ca salts. MethodsThe EX adhesives were prepared by varying the amounts of MDP (25.6, 49.9, 80.5 and 116.1mg) added in 1g of the EX adhesive. Enamel and dentin reactant residues were obtained after the reaction of each EX adhesive to enamel or dentin particles for 30s. The chemical analyses of both reactant residues were then performed. ResultsThe molecular species of MDP-Ca salts that form a layered structure were determined as mono-calcium salt (MCS-MD) and di-calcium salts of the MDP dimer (DCS-MD). The dentin sample showed two types of characteristic XRD peaks assigned to the layer structure, since the dentin produced DCS-MD along with MCS-MD in contrast to the enamel sample. A mono-calcium salt of the MDP monomer (MCS-MM), a predominant molecular species, was not contributed to a layered-structure formation, since the intensities of characteristic XRD peaks are limited by the production of DCS-MD and MCS-MD. SignificanceThe self-assembled layering of MCS-MD and DCS-MD is associated by a hydrophobic bond between two 10-methylene groups in MCS-MD and DCS-MD. The MCS-MD may form a more tightly-packed layered structure than DCS-MD by the hydrogen bonded interaction between hydroxy groups bonded to each phosphorous atom.

Effect of Scrubbing Technique with Mild Self-etching Adhesives on Dentin Bond Strengths and Nanoleakage Expression.

To evaluate the effect of a scrubbing technique with one-step self-etching adhesives on bond strengths and nanoleakage expression at the resin/dentin interface. Flat human dentin surfaces bonded with one of two mild self-etching adhesives, SE One (SE) or Scotchbond Universal (SU) applied either with scrubbing or without scrubbing technique, were prepared (n = 5). The microtensile bond strengths (μTBS), SE micrographs of morphological changes on treated dentin surfaces, and expression of nanoleakage along the bonded dentin interfaces as shown with TEM were evaluated. μTBS data were analyzed using two-way ANOVA and the post-hoc t-test at the significance level of 0.05. The scrubbing technique had a significant positive effect on the μTBS of SU (p < 0.05), while it produced no significant difference for SE (p > 0.05). Morphological evaluation of the treated dentin surfaces demonstrated that SU with scrubbing showed the highest etching ability, followed by scrubbing SE > nonscrubbing SE > nonscrubbing SU. In the nonscrubbing groups, nanoleakage formation using SU exhibited a reticular pattern throughout the hybridized complex, whereas with SE, water-tree nanoleakage was only found in the adhesive layer at dentinal tubule orifices. The scrubbing groups of both adhesives did not exhibit any nanoleakage expression. Using a scrubbing technique when applying mild self-etching adhesives could improve resin monomer infiltration into dentin, chase water on adhesive surfaces, and facilitate smear layer removal.