G-Premio Bond Research Articles

Bioactive Two-step Approach: Promising Bonding Strategy for a One-step Self-etch Universal Adhesive.

To evaluate the potential of an additional application of two novel hydrophobic experimental adhesive resins with or without bioactive zinc fluoride glass to promote the bond strength of a one-step self-etch universal adhesive. Three self-etch universal adhesives, G-Premio Bond (GPB), Scotchbond Universal (SBU) and Clearfil SE Bond 2 (SE2), and two experimental adhesive resins, BZF210 and BZF21, were used in this study; thus, five groups were formed: GPB, GPB+BZF210, GPB+BZF21, SBU, and SE2. The adhesives were applied to flat dentin surfaces according to each manufacturer's instructions. The microtensile bond strengths (μTBS) were evaluated after 24-h water storage. The fracture modes and interfacial structures were analyzed using SEM, while elemental analysis was performed using SEM-EDS. The data were analyzed using one-way ANOVA and the Games-Howell test (p < 0.05). Significantly higher μTBS was achieved by additional application of BZF210 (48.68 ± 6.59 MPa) and BZF21 (58.58 ± 2.84 MPa) compared with GPB (33.57 ± 4.22 MPa) alone. Most failures occurred above the smear layer in GBP, while more cohesive and mixed failures were observed in GBP+BZF210, GPB+BZF21, SBU, and SE2. The interfacial structures revealed that GBP+BZF210 and GPB+BZF21 had more and longer resin tags than did GPB. SEM-EDS showed a particularly high peak of zinc in GPB+BZF21. The bond strength of GPB was significantly improved by the additional application of BZF210 and BZF21. Using an additional bioactive hydrophobic layer on a one-step, self-etch universal adhesive can significantly improve its bonding efficacy and extend its clinical options.

Comparison of self-adhering flowable composite microleakage with several types of bonding agent in class V cavity restoration

The aim of the present study was to compare the marginal seal of self-adhering flowable composite resin with three universal bonding systems using the self-etch technique in Cl V cavities at enamel and dentin margins. In this in vitro study, Cl V cavities were prepared on the buccal surfaces of forty premolars, with the occlusal margin of each cavity on enamel and gingival margin on dentin. The teeth were divided into four groups (n = 10) in terms of the adhesive used; Group 1: Vertise Flow (VF) self-adhering composite resin, Group 2: Clearfil S3 Bond Universal (CS3BU), Group 3: G-Premio Bond (GPB), Group 4: Single Bond Universal (SBU). In Groups 2, 3, and 4, Z350 flowable composite resin was used to restore the cavities. After thermocycling, the samples were immersed in 10% methylene blue for 24 h and evaluated under a stereomicroscope after buccolingual sectioning; microleakage at enamel and dentin margins was recorded. Kruskal-Wallis and Mann-Whitney tests were used for statistical analyses. Statistical significance was set at P < 0.5. Vertis Flow self-adhering composite resin exhibited significantly higher microleakage at enamel and dentin margins compared to SBU and CS3BU; however, it had significantly less microleakage at enamel margin compared to GPB (P < 0.05). At the enamel and dentin margins, the minimum microleakage values were recorded at SBU and CS3BU margins, respectively. GPB exhibited the highest microleakage values among the groups evaluated and in all the groups, microleakage at dentin and enamel margins was significantly different (P < 0.05) except for SBU group. The marginal sealing ability of self-adhering flowable composite resin at enamel and dentin margins was poor compared to the majority of bonding agents evaluated.

Effect of Office Bleaching on Enamel Bonding Performance.

To evaluate the effect of in-office bleaching on enamel microshear bond strength (µSBS) of two self-etch adhesives (SEA). For the bleaching group, bovine enamel surfaces were treated with a bleaching agent and divided into two main groups: one in which adhesive was applied immediately after bleaching and another in which adhesive was applied after one week. Enamel was bonded using the following procedures: group 1: application of a two-step SEA (Clearfil SE Bond 2, SE2, Kuraray Noritake); group 2: etching with 40% phosphoric acid (PA) and application of SE2;.group 3: application of a one-step SEA (G-Premio Bond, GP, GC); group 4: etching with PA and application of GP. Resin composite was placed and µSBS was measured at 24 h (immediately) and 1 week after bleaching. Acid-base resistant zones (ABRZ) were observed under SEM. Three-way ANOVA was used for data analysis. Bleaching significantly decreased the µSBSs even after PA etching with both SE2 and GP (p ≤ 0.005). However, there were no significant differences in µSBS between groups with and without PA etching, except for SE2 without bleaching, in which the µSBS significantly increased with PA etching (p < 0.005). Thick ABRZs were found in SE2 and GP after bleaching, which exhibited an irregular wave-like shape for PA-treated specimens. The enamel µSBSs were adversely affected by in-office bleaching. Thick ABRZs were created with bleaching and PA treatment.

Effect of Different Surface Treatment Modalities on Surface Roughness and Shear Bond Strength of Orthodontic Molar Tubes to Lithium Disilicate Ceramics

Objectives; This study aimed to evaluate the effect of different surface treatment modalities on surface roughness(SR) and shear bond strength (SBS) of orthodontic molar tubes to lithium disilicate (IPS e-max CAD/CAM, Ivoclar Vivadent) ceramic and human enamel using different adhesives.Materials and methods: A total of 150 e-max specimens were randomly divided into five groups (n=30) according to the method of surface treatment used. In group I (control group): no surface treatment, group II: sandblasting with 50 μm Al2O3 slurry particles, group III: etching with hydrofluoric acid 9.6%, group IV: etching with hydrofluoric acid 4.5% and group V: etching with phosphoric acid 37%. Further random distribution of e-max specimens into subgroups was performed according to the type of adhesive used (One coat 7, G-Premio Bond and Ortho solo). The surface roughness was investigated using digital profilometer and atomic force microscopy (AFM). Microstructural analysis was conducted using scanning electron microscope (SEM).The SBS was measured using universal testing machine. Results were statistically analyzed.Results: Results showed that the sandblasting group had significantly highest surface roughness, while the lowest value was recorded in the Phosphoric acid 37% group. Furthermore, sandblasted group showed the highest SBS, while control group showed the lowest SBS. Strong positive correlation was found between the surface roughness of lithium disilicate and shear bond strength. Meanwhile, no significant differences were found between different adhesive agents use.Conclusions: Shear bond strength was highly affected by the surface roughness which subsequently controlled by the surface treatment modalities and not by the adhesives types. Hydrofluoric acid 4.5% and phosphoric acid 37% are recommended techniques for reliable bond strength between metal tubes and lithium disilicate ceramic.

Grape Seed Extract Reduces Active Gelatinases Using an Etch-and-Rinse Mode Universal Adhesive.

To examine the effect of grape seed extract (GSE) pretreatment on the reduction of active gelatinases when using universal adhesives in etch-and-rinse mode. Fifty extracted non-carious human teeth were used in this study. Dentin powder was prepared for analysis of active MMP-2 by ELISA. Resin-dentin slices were prepared for in situ zymography in order to localize active gelatinases by quenched fluorescein-conjugated gelatin under a confocal microscope. Fluorescence intensity was analyzed quantitatively. Specimens were allocated into 6 groups: a non-treated control, phosphoric acid etched (PA), PA followed by Single Bond Universal (SBU, 3M Oral Care) or G-Premio Bond (GPB, GC), and PA followed by GSE for 1 min prior to SBU or GPB. The data were analyzed with one-way ANOVA and Bonferroni's test at a significance level of 0.05. Application of the universal adhesives SBU and GPB in etch-and-rinse mode reduced active MMP-2 in dentin matrices. However, the only further significant reduction was found in GPB pre-treated with GSE, as analyzed by ELISA. In situ zymography demonstrated the location of active gelatinases, and fluorescence intensity analysis confirmed significant reduction of active gelatinases in the hybrid layer of GPB pre-teated with GSE compared to GPB alone. The present study demonstrated the potential advantage of applying GSE to reduce active gelatinases especially at the hybrid layer, with greater benefit achieved for hydrophobic adhesives. Nevertheless, the mechanism of action, analysis of bond strength, and long-term efficacy require further study.

Etch-and-rinse vs self-etch mode for dentin bonding effectiveness of universal adhesives.

In this study, dentin bond fatigue resistance and interfacial science characteristics of universal adhesives through etch-and-rinse and self-etch modes were investigated. Resin composite was bonded to human dentin with four universal adhesives, namely, Adhese Universal, All-Bond Universal, G-Premio Bond, and Scotchbond Universal Adhesive. The initial bond strengths, bond fatigue strengths, and interfacial science characteristics of the universal adhesives with dentin through etch-and-rinse and self-etch modes were determined. Bond fatigue resistance (initial bond strength and bond fatigue strength) of universal adhesives in etch-and-rinse mode showed no significant difference in contrast to that in self-etch mode and was material-dependent regardless of the etching mode. Although phosphoric acid conditioning of dentin did not have a strong impact on the bond fatigue resistance, surface free energy and parameters of dentin were significantly decreased by etching and by application of universal adhesives regardless of etching mode. Changes in γS and γSh for when universal adhesive was applied to etched and ground dentin were significantly different depending on the adhesive. The results suggest that bonding performance of universal adhesives was effective in both etching modes; however, bonding mechanisms may be different for each.

Do Universal Adhesives Benefit from an Extra Bonding Layer?

Universal adhesives use a combined primer/bonding resin applied either in 2-step etch-and-rinse (2-E&R) or 1-step self-etch (1-SE) mode. This study investigated whether three universal adhesives would benefit from an extra bonding layer (EBL), essentially making them 3-step E&R (3-E&R) and 2-SE adhesives, respectively. Microtensile bond strengths (μTBSs) to bur-cut dentin of Clearfil Universal Bond Quick (C-UBq, Kuraray Noritake), G-Premio Bond (G-PrB, GC) and Prime&Bond Active (P&Ba, Dentsply Sirona) were compared to those of the 2-SEa Clearfil SE Bond 2 (C-SE2, Kuraray Noritake) which was also employed in 3-E&R mode. A split-tooth design was applied with each adhesive used in E&R and SE mode on each tooth, half without/with EBL (C-SE2 Bond). All adhesives were light cured after application of the final layer. The μTBS of one-third of the specimens was measured after 1-month water storage without thermocycling (TC), with the remaining two-thirds aged with 25,000 and 50,000 TCs. All μTBSs were statistically analyzed using a linear mixed-effects model with specific contrasts (p < 0.05). Overall, the four variables (adhesive, bonding mode, EBL, aging) significantly influenced μTBS. Solely G-PrB benefited from EBL when applied in SE mode. In E&R mode, P&Ba generally resulted in the highest µTBSs, C-UBq presented with intermediate and G-PrB with the lowest µTBSs, where the latter was significantly lower than the µTBSs recorded for C-SE2. In SE mode, P&Ba generally resulted in the highest µTBSs in 1- and 2-SE mode. Equally high µTBSs were recorded for G-PrB in 2-SE mode with EBL. Lower µTBSs were recorded for G-PrB in 1-SE mode and for C-UBq in 1- and 2-SE mode. The overall effect of EBL on immediate and aged bonding efficacy depended on the specific universal adhesive and its bonding mode.

In vitro Comparative Study on the Marginal Adaptation of Direct, Semi-direct and Indirect Composite Resins Restorations to Dentine and Dental Cementum

The aim of the present study is to compare the marginal adaptation of direct, semi-direct and indirect restorations made with nanofill and microhybrid composite materials and ormocers materials bonded with SE adhesives at the dentin and cementum. 120 standardized class II cavities were prepared (40 for each techniques- RD, RSD, RI) with the gingival margin over and below to the cementum-enamel junction. The teeth (n= 20) were restored using one of three adhesive systems (OptiBond XTR, G-Premio Bond bottle refill, Futurabond U) with incrementally placed composite restorations and ormocers. After applying the various restorations, the teeth were prepared for SEM analysis to check the marginal adaptation by the presence of continuous margins or gaps. Comparative analysis of treatment methods and materials used was performed by statistical analysis of Chi-square test data, the statistical significance was p [0.05 and Fisher�s Exact Test for validation of results. It was found that among the three materials used for RD, RSD, RI both at the dentin and the cementum, there are no significant differences (RD d = 0.661, RSD/d = 0.755, RSD/c = 0.942; RI/d = 0.739; RI/c = 0.985). Comparison between the presence of continuous margins/gaps subgingivally and supragingivally at the three types of restorations shows that there are significant differences between the marginal adaptation at the cementum and dentin to all the restoration techniques used (p [0.05). Direct and indirect restorations with nanocomposites and ormocers bonded with 1-step SE adhesive are the best solutions for restoring the posterior teeth.

Internal adaptation of composite restorations with or without an intermediate layer: Effect of polymerization shrinkage parameters of the layer material

ObjectivesThe purpose of this study was to compare the internal adaptation of resin composite restorations in Class I cavities with or without an intermediate layer, and to identify the relationships between the internal adaptation and the polymerization shrinkage parameters of the layer material. MethodsClass I cavities prepared in human third molars were treated with a one-step self-etch adhesive (G-Premio Bond, GC). In the control group, Tetric-EvoCeram Bulk-Fill (TBF, Ivoclar Vivadent) was placed using the bulk-fill technique and then light-cured. In the experimental groups, six different layer materials (three flowable resin composites, two bulk-fill resin composites, and a resin-modified glass-ionomer) were applied to a 1.5-mm thickness and light-cured, which was followed by TBF filling. After thermo-cycling, internal adaptation was measured using swept-source optical coherence tomography (SS-OCT) imaging and compared in terms of high brightness percentage (HB%) to represent the microgap. Shrinkage strain (SS), flexural modulus (FM), and polymerization shrinkage stress of the intermediate layer-resin composite complex (PS) were measured for each material. The relationships among HB%, SS, FM, and PS were evaluated statistically. ResultsGroups with an intermediate layer showed lower HB% than the control group. The HB% correlated with PS (Pearson’s correlation: R2 = 0.883, p < 0.05), and the PS correlated with the product of SS and FM. ConclusionInternal adaptation depended on the polymerization shrinkage stress of the intermediate layer-resin composite complex. Clinical significanceBulk-fill resin composite, which can show low polymerization shrinkage stress, may be used as an intermediate layer for better internal adaptation.

Effect of various agitation methods on adhesive layer formation of HEMA-free universal dentin adhesive.

This study evaluates the effects of various agitation methods on the adhesive layer formation of a new HEMA-free universal dentin adhesive. The µTBS of the universal adhesive, G-Premio BOND in the self-etch mode was evaluated using three agitation methods [passive agitation (PA), active agitation (AA), ultrasonic agitation (UA)], with and without aging treatment. Two-way analysis of variance revealed that aging treatment was not a statistically significant factor. Tukey's HSD test showed significant differences based on the application method, UA>AA>PA. TEM images of the PA group revealed multiple water blisters in the adhesive layers; AA and UA groups presented significantly less or no blisters within the adhesive layers; thus, AA and UA groups exhibited better bonding performance for the HEMA-free universal adhesive. It is assumed that the entrap ped blisters can be reduced with the active application of dentin adhesive, and thus improving the bonding performance.

Bond strength of three different universal adhesives after different thermal cycling protocols

The purpose of this study was to examine the bond strength of three different universal adhesives on enamel after different aging periods. Ninety enamel specimens were prepared and randomly assigned into three groups according to different universal adhesive systems (n = 30): iBOND Universal (IB), G-Premio Bond (GP), Clearfil Universal Bond Quick (CU). All adhesives were applied at etch&rinse mode. A cylinder-shaped resin composite was placed on enamel surfaces and light cured. Then all specimens were stored in distilled water at 37 °C for 24 h and divided into 3 thermal cycling protocol groups (n = 10): No thermal cycling (NTC), 10,000 thermal cycles (10TC), 40,000 thermal cycles (40TC). Specimens were subjected to shear bond strength (SBS) test at a universal testing machine. Failure modes were determined and SEM analyses were performed for each failure mode. Data were analyzed using two-way ANOVA followed by Tukey HSD test. The highest SBS values were observed at NTC groups. The 40TC groups showed significantly lower SBS values than other groups (p < 0.05). The highest mean SBS values were obtained in IB at NTC group (p < 0.05). After 10TC, all universal adhesives exhibited similar SBS values (p > 0.05), however after 40TC, CU showed higher SBS than GP. The mean shear bond strength to enamel was significantly affected by thermal cycling (p < 0.05). The enamel bond durability of universal adhesives dractically decreased after 10,000 and 40,000 thermal cycling periods. The universal adhesives tested showed different SBS values at NTC and after 40TC.

Do collagen cross-linkers improve dentin’s bonding receptiveness?

ObjectivesDentin biomodification using collagen cross-linkers has been proposed as one of the strategies to improve bond durability of adhesives to dentin. However, literature is not very consistent regarding their benefit, in particular when cross-linkers are applied in clinically realistic application times. This study investigated the effect of three cross-linkers on the mini-interfacial fracture toughness (mini-iFT) of four adhesives bonded to dentin following either etch&rinse (E&R) or self-etch (SE) modes. Methods60 molars were randomly divided in accordance with the three variables: cross-linker, adhesive and bonding mode (n=5). The cross-linkers glutaraldehyde (5wt%; GA), proanthocyanidin (6.5wt%; PA), or UVA-activated riboflavin (0.5wt%; RB), and distilled water (control) were applied on dentin for 60s after acid-etching (E&R) or before self-etching (SE). The 3-step E&R adhesive (3E&Ra) OptiBond FL (Kerr), the 2-step SE adhesive (2SEa) Clearfil SE Bond 2 (Kuraray Noritake) and the universal adhesives G-Premio Bond (GC) and Prime&Bond Active (Dentsply), the latter two employed in both E&R and SE modes, were applied following the respective manufacturer’s instructions. Composite buildups (8×8×8mm) were made using Filtek Supreme XTE (3M) prior to 1-week storage in artificial saliva. After the teeth were sectioned into mini-specimens (1.5×2.0×18mm), a single notch was prepared at the adhesive–dentin interface. Half of the specimens were immediately loaded until failure by 4-point bending to determine the mini-iFT, while the remaining specimen set was tested upon 6-month aging. Data were statistically analyzed with a linear model (p<0.05). ResultsNo significant decrease in mini-iFT was noted only for PA (p<0.05), while the mini-iFT decreased for both other cross-linkers and in quite a similar way as when solely water (Wa) was applied. SignificanceThe cross-linker proanthocyanidin (PA) applied in clinically relevant conditions was able to maintain a stable mini-iFT after 6-month aging. The incorporation of UVA-activated riboflavin (RB) and glutaraldehyde (GA) in the dentin-bonding protocol appeared not effective to improve the stability of adhesive–dentin interfaces.

An 18-month clinical evaluation of three different universal adhesives used with a universal flowable composite resin in the restoration of non-carious cervical lesions.

The aim of this randomized, controlled prospective clinical trial was to evaluate and compare the performances of three different universal adhesives using a flowable universal composite resin in the restoration of non-carious cervical lesions (NCCLs) over an 18-month period. Eighteen participants recieved 99 restorations from a single operator. NCCLs were divided into three groups according to adhesive systems used: Clearfil Universal Bond (CU), iBOND Universal (IU), and G-Premio Bond (GP). No enamel bevel was placed and no mechanical retention was created for the NCCLs. Prior to adhesive procedures, selective etching was performed with 37% phosphoric acid. Adhesive systems were applied following manufacturers' instructions and the lesions were restored with a flowable composite resin (G-ænial Universal Flo). Restorations were finished and polished immediately after placement and scored with regard to retention, marginal discoloration, marginal adaptation, sensitivity, surface texture, and color match using modified USPHS criteria after a week (baseline) and 6, 12, and 18months. Descriptive statistics were performed using chi-square tests. The 18-month recall rate was 88.8% and retention rates for CU, IU, and GP were 100%, 96.8%, and 100%, respectively. No restorations exhibited post-operative sensitivity and secondary caries. After 18months, CU, IU, and GP groups showed similar alpha rates for marginal adaptation (CU 93.1%, IU 90%, GP 81.8%) and marginal discoloration (CU 100%, IU 90%, GP 87.9%). A total of ten (CU 2, IU 3, GP 5) restorations exhibited bravo scores for surface texture and three (CU 2, GP 1) restorations showed bravo score for color match. No statistical differences were found among the tested adhesives for any criteria evaluated (p > 0.05). The three adhesive systems demonstrated similar performances during the 18-month follow-up in the restoration of NCCLs. Universal adhesives could be used successfully in the restoration of NCCLs.

Shear fatigue strength of resin composite bonded to dentin at physiological frequency.

The purpose of this study was to examine the shear fatigue strengths of a resin composite bonded to dentin. Three adhesive systems - a two-step self-etch adhesive (OptiBond XTR; Kerr) and two universal adhesives [Scotchbond Universal (3M ESPE) and G-Premio Bond (GC)] - were used in self-etch mode to bond a resin composite to dentin at a physiologic frequency of 2 Hz over 50,000, 100,000, and 1,000,000 cycles. A staircase method of fatigue testing was used. Twenty specimens were used for each test condition. There was no significant difference in shear fatigue strength across the cycling periods for the three individual adhesives. Differences in shear fatigue strength were found among the three adhesives within each cycling period. Regardless of the adhesive used in self-etch mode for bonding a resin composite to dentin, shear fatigue strength was not influenced by the number of cycles used for testing.

Effect of Reduced Universal Adhesive Application Time on Enamel Bond Fatigue and Surface Morphology.

The purpose of this study was to evaluate the effect of reduced application times of universal adhesives on enamel bond fatigue and surface morphology of the treated enamel with constant force atomic force microscopy (AFM). Four universal adhesives-Adhese Universal (AU), Clearfil Universal Bond Quick (CU), G-Premio Bond (GP), and Scotchbond Universal Adhesive (SU)-were evaluated in a laboratory for their ability to adhesively bond resin composite to enamel. Shear bond strengths were initially determined using 15 specimens per test group for each adhesive. Shear fatigue strengths were then determined using 20 specimens per test group for each the adhesives. The fatigue specimens were loaded using a sine wave at a frequency of 20 Hz for 50,000 cycles or until failure occurred. AFM observations, surface Ra roughness measurements, and geometric surface area evaluations of enamel surface treated with the adhesive agents were also conducted. A strong relationship was found between the initial shear bond strength and shear fatigue strength for enamel surface Ra roughness but not for geometric surface area. The initial shear bond strength and shear fatigue strength of CU and GP were not influenced by different application times, unlike those of AU and SU. While the surface area of enamel treated with the adhesive agents was not significantly influenced by different application times and type of adhesive, surface Ra roughness of the enamel in the AU and SU groups significantly increased with increasing application time, unlike CU and GP. The results of this study suggest that universal adhesives, used with reduced application times, have adequate Ra surface roughness to provide sufficient resistance to enamel bond fatigue at application times from <1 second to 20 seconds, while the geometric surface area of adhesive-treated enamel did not show any significant changes at these different application times.

Effects of three silane primers and five adhesive agents on the bond strength of composite material for a computer-aided design and manufacturing system.

ObjectiveThe objective of this study was to evaluate the effects of combinations of silane primers and adhesive agents on the bond strength of a composite block for a computer-aided design and manufacturing system.Material and MethodsThree silane primers [Clearfil Ceramic Primer (CP), Super-Bond PZ Primer (PZ), and GC Ceramic Primer II (GP)] were used in conjunction with five adhesive agents [G-Premio Bond (P-Bond), Repair Adhe Adhesive (R-Adhesive), Super-Bond D-Liner Dual (SB-Dual), Super-Bond C&B (SB-Self), and SB-Dual without tributylborane derivative (SB-Light)]. The surface of a composite block (Gradia Block) was ground with silicon carbide paper. After treatment with a silane primer, a adhesive agent was applied to each testing specimen. The specimens were then bonded with a light-curing resin composite. After 24 h, the shear bond strength values were determined and compared using a post hoc test (α=0.05, n=8/group). We also prepared control specimens without primer (No primer) and/or without adhesive agent (No adhesive).ResultsPZ/SB-Dual and GP/SB-Dual presented the highest bond strength, followed by GP/P-Bond, CP/SB-Dual, CP/R-Adhesive, No primer/SB-Dual, GP/R-Adhesive, CP/P-Bond, No primer/R-Adhesive, PZ/R-Adhesive, CP/SB-Self, PZ/P-Bond, PZ/SB-Self, and GP/SB-Self in descending order of bond strength. No primer/P-Bond, No primer/SB-Self, and all specimens in the SB-Light and No adhesive groups presented the lowest bond strengths.ConclusionA dual-curing adhesive agent (SB-Dual) containing a tributylborane derivative in combination with a silane primer (GP or PZ) presents a greater bond strength between the composite block and the repairing resin composite than the comparators used in the study.

Does Shortened Application Time Affect Long-Term Bond Strength of Universal Adhesives to Dentin?

This study evaluated the effect of shortened application time on long-term bond strength with universal adhesives. Three universal adhesives were used: Clearfil Universal Bond (CU, Kuraray Noritake Dental Inc, Tokyo, Japan), Scotchbond Universal Adhesive (SB, 3M ESPE, St Paul, MN, USA) or G-Premio Bond (GP, GC Corp, Tokyo, Japan). Sixty molars were cut to expose midcoronal dentin and prepared with a regular diamond bur. Each adhesive was applied either according to the manufacturer's instruction or with shortened time. Specimens were stored in distilled water at 37°C for 24 hours and then cut into resin-dentin sticks. Microtensile bond strength (μTBS) was tested after either 24 hours or 1 year of water storage. Data were analyzed by the three-way ANOVA and Duncan tests ( α=0.05). Fracture modes were analyzed under a scanning electron microscope (SEM). One dentin stick per group was selected after fracture mode analysis and further observed using transmission electron microscopy (TEM). Six additional dentin discs were prepared and conditioned with each adhesive under the different application time to observe the adhesive-smear layer interaction by SEM. Shortened application time affected the μTBS ( p<0.001) while storage time did not affect bond strength ( p=0.187). A significant effect of shortened application time on μTBS was observed in the CU at 1 year and in the GP at both storage times. One-year storage time had no effect on the μTBS of universal adhesives to bur-cut dentin. The performance of universal adhesives can be compromised when applied using a shortened application time.

Effects of Selective Phosphoric Acid Etching on Enamel Using "No-wait" Self-etching Adhesives.

To evaluate the effect of selective phosphoric acid etching on enamel using "no-wait" self-etching adhesives. Clearfil Universal Bond Quick (UBQ, Kuraray Noritake) or G-Premio BOND (GPB, GC) was applied to ground human enamel surfaces. The adhesives were used in 3 modes: no-waiting self-etching mode (UBQ-0 or GPB-0), 10-s self-etching mode (UBQ-10 or GPB-10), and the selective-etch mode with phosphoric acid etching (UBQ-PA or GPB-PA). After an acid-base challenge, the morphological attributes of the interface were examined using scanning electron microscopy (SEM) to characterize the acid-base resistant zone (ABRZ). Microshear bond strength (µSBS) testing to enamel and ultimate tensile strength (UTS) of the adhesive resin were carried out. ABRZ formation was confirmed in all groups. UBQ-PA and GPB-PA created thicker ABRZ with no funnel-shaped erosion beneath the adhesive-enamel interface. µSBS of UBQ-PA was significantly higher than UBQ-0 and UBQ-10 (p < 0.05). However, there were no statistically signficant differences in µSBS among GPB-0, GPB-10, and GPB-PA. For the UTS, UBQ was significantly higher than GPB. Selective phosphoric acid etching created a stable adhesive-enamel interface. The no-waiting self-etching concept adhesive led to a thinner ABRZ. The results of µSBS suggest that phosphoric acid etching effects on enamel are material dependent.

Influence of Application Time and Etching Mode of Universal Adhesives on Enamel Adhesion.

To investigate the influence of application time and etching mode of universal adhesives on enamel adhesion. Five universal adhesives, Adhese Universal, Bondmer Lightless, Clearfil Universal Bond Quick, G-Premio Bond, and Scotchbond Universal, were used. Bovine incisors were prepared and divided into four groups of ten teeth each. SBS, Ra, and SFE were determined after the following procedures: 1. self-etch mode with immediate air blowing after application (IA); 2. self-etch mode with prolonged application time (PA); 3. etch-and-rinse mode with IA; 4. etch-and-rinse mode with PA. After 24-h water storage, the bonded assemblies were subjected to shear bond strength (SBS) tests. For surface roughness (Ra) and surface free energy (SFE) measurements, the adhesives were simply applied to the enamel and rinsed with acetone and water before the measurements were carried out. Significantly higher SBS and Ra values were obtained with etch-and-rinse mode than with self-etch mode regardless of the application time or type of adhesive. Although most adhesives showed decreased SFE values with increased application time in self-etch mode, SFE values in etch-and-rinse mode were dependent on the adhesive type and application time. Etching mode, application time, and type of adhesive significantly influenced the SBS, Ra, and SFE values.

Shear Bond Strength of Metal Brackets to Porcelain Using a Universal Adhesive.

Introduction: Bracket bonding to porcelain has high failure rate compared to bonding to enamel.Aim:This study aimed to assess the shear bond strength (SBS) of metal brackets to porcelain using a universal adhesive. Material and Methods:In this in vitro experimental study, 40 porcelain blocks (1x1x1 cm3)were divided into four groups (n=10). The porcelain surfaces were etched with 10% hydrofluoric (HF) acid and bonded to metal brackets using Transbond XT composite and the following bonding protocols: Transbond XT bonding agent alone in group 1, silane plus Transbond XT bonding agent in group 2, silane plus universal adhesive (G-Premio bond) in group 3 and universal adhesive alone in group 4. The SBS was measured using a universal testing machine at a crosshead speed of 1 mm/minute. Fracture surfaces were evaluated under a stereo microscope, and the adhesive remnant index (ARI) scores were determined. Results: The highest and the lowest SBS values were noted in groups 3 (17.06±2.58 MPa) and 4 (9.85±4.76 MPa), respectively. Type of adhesive had no significant effect on SBS (P=0.611). However, the effect of application of silane on SBS was significant (P=0.000). Groups subjected to the application of silane showed higher SBS values than others. The mode of failure was mainly adhesive in groups 2 and 3, and adhesive and mixed in groups 1 and 4. The difference in ARI scores was statistically significant (P=0.016). Conclusion: Universal adhesive and Transbond XT were not significantly different in SBS. However, application of silane significantly increased the bond strength.