Microtensile Bond Strength and Failure Type Analysis of Self-Etch Adhesive Systems on Superficial and Deep Dentin After Long-term Water Storage

Objectives:To evaluate the effect of different bonding strategies on the microtensile bond strength to deep and superficial permanent dentin.Methods:Forty-eight teeth were randomly flattened according to the dentin depth: superficial dentin (SD) and deep dentin (DD). Subsequently, three adhesive systems were applied (n=8): an etch-and-rinse (Adper Single Bond 2 - SB), a “mild” two-step self-etching (Clearfil SE Bond - SE) and a one-step self-etching adhesive system (Futurabond – FB). Each specimen was restored with a composite resin and sectioned into 1.0-mm2 thick slabs. After 24 hours, resin-dentin sticks were submitted to tensile stress in a universal testing machine (0.5 mm/min). Data were submitted to two-way ANOVA and Tukey’s test at a level of 0.05%.Results:Superficial dentin showed the highest microtensile bond strength values, which differed statistically from those obtained in the deep dentin, irrespective of the adhesive system used. FB yielded the highest bond strength values, which were statistically similar to the bond strength values of SE, but statistically different from those obtained when the SB adhesive was used.Conclusions:Bond strength obtained in superficial dentin was significantly higher than in deep dentin, for all adhesive systems tested. Adhesion was affected by the different bonding strategies: the one-step, low pH, acetone-based self-etching adhesive promoted the higher bond strength values, which were statistically similar to those obtained with the two-step, water-based self-etching adhesive.

The success of adhesive restorations largely depends on the optimal bond strength between the tooth structure and the restorative material. The aim of this study was to evaluate the shear bond strength (SBS) of four different adhesives applied to mandibular molars on deep and superficial dentin. The total of 56 teeth used in the study were randomly divided into 2 subgroups of superficial dentin and deep dentin participants (n = 28). Superficial and deep dentin groups were randomly divided into 4 subgroups (n = 7) for application with different adhesive agents. We formed the following groups: Group 1 (G1)-deep dentin and GC bonding agent (G-Premio BOND); Group 2 (G2)-superficial dentin and GC bonding agent; Group 3 (G3)-deep dentin and Clearfil S3 bond bonding agent (Clearfil TM S3 BOND); Group 4 (G4)-superficial dentin and Clearfil S3 bond bonding agent; Group 5 (G5)-deep dentin and KerrOptibond bonding agent (KerrOptibondTM Universal); Group 6 (G6)-superficial dentin and Kerr Optibond bonding agent; Group 7 (G7)-deep dentin and 3M-ESPE universal bonding agent (3M ESPE); Group 8 (G8)-superficial dentin and 3M-ESPE universal bonding agent. The silicone block with a diameter of 3 mm and a thickness of 1 mm was placed in the middle of the occlusal surface and the test composite was loaded. All prepared specimens were aged in thermal cycles at 5-55 °C for 5000 cycles. The teeth were subjected to SBS (shear bond strength) tests at a crosshead speed of 1 mm/min in a universal testing machine. In all adhesive systems, deep dentin showed a higher bond strength than superficial dentin and the bond strength value was statistically significant (p = 0.05). The bond strength in all tested adhesive systems was observed to be significantly higher in deep dentin than in superficial dentin.

The aim of the present in vitro study was to evaluate the effect of chlorhexidine, applied before a self-etching adhesive system (Clearfil SE Bond) on microtensile bond strength to superficial and deep dentin (DD), immediately and after six months of water storage (WS). Forty dentin specimens were divided into two groups according to dentin depth: superficial and deep. The specimens were then divided according to the solution to be applied (n = 10): CLX: 2% chlorhexidine (passively applied for 60 s) and NT (no treatment). A self-etching adhesive system was applied according to the manufactures instructions, with composite restorative placed on the dentin surface. After 24 h, dentin–resin blocks were sectioned into beam-shaped specimens that were submitted to microtensile bond strength testing either immediately or after six months of WS. Data were submitted to three-way ANOVA (α = 0.05). Bond strength values for the deep dentin group were significantly lower than those observed for superficial dentin (SD) (p = 0.002), whether chlorhexidine solution had been applied or not. There was no statistical difference in bond strength for specimens tested after 24 h and 6 months of WS. The application of chlorhexidine did not affect immediate and long-term bond strength to dentin. Bond strength in deep dentin was lower than in SD.

One-bottle universal adhesives have been widely used because of their simplicity of bonding procedures for various dental materials. The present study evaluated the effect of the polymerization light source on the micro-tensile bond strengths of a universal adhesive (Clearfil Universal Bond Quick) to dentin in comparison with a one-bottle self-etch adhesive (Clearfil S3 Bond Plus) and two 2-step self-etch adhesives (Clearfil SE Bond and Clearfil SE Bond 2). The adhesives were applied to extracted human dentin according to the manufacturer’s instructions and irradiated using either a quartz-tungsten-halogen (QTH) or blue light-emitting diode (LED). Subsequently, a resin composite was incrementally built on each adhesive and light-cured using the QTH. The bonded specimens were sectioned and subjected to micro-tensile bond strength tests. Both the type of adhesive and the light source were found to statistically affect the bond strength, with no interactions. The LED gave greater bond strength than the QTH. The bond strengths of the two-step adhesives were significantly higher than those of the one-bottle products, irrespective of the light source. The Clearfil Universal Bond Quick exhibited significantly higher bond strength than the Clearfil S3 Bond Plus. LED curing improved the performance of Clearfil Universal Bond Quick, and this product generated bond strength superior to that of the existing one-bottle adhesive Clearfil S3 Bond Plus.

OBJECTIVE: Adhesive systems used with brackets should provide sufficient bond strength to withstand forces duringmastication and orthodontic treatment. The purpose of this in vitro study was to assess the shear bond strength (SBS) and failure sites of different metallic and ceramic brackets by two different bonding systems. MATERIALS AND METHOD: Sixty-eight caries-free human mandibular premolars were randomly assigned to 4 groups of 17 each. Group 1 consisted of metallic brackets bonded with Transbond XT; Group 2 consisted of metallic brackets bonded with Clearfil S3 Bond Plus; ceramic brackets bonded with Transbond XT and Clearfil S3 Bond Plus composed Groups 3 and 4, respectively. A universal testing machine was used to determine the SBS, and the adhesive remaining after debonding was assessed using an adhesive remnant index (ARI). RESULTS: The bond strength of metallic brackets was significantly lower than the ceramic ones. Ceramic brackets bonded with Clearfil S3 Bond Plus declared the highest bond strength (p<0.001), revealing a mode of bond failure at the enamel-adhesive interface. However, the mode of failure for the conventional system was cohesive at the composite interface, showing a statistically significant difference between groups (p<0.05). CONCLUSION: Although all bonding systems provided adequate SBS values, Clearfil S3 Bond Plus requires a careful clinical application due to high bond strength and ARI scores. In relation to present findings, the conventional bonding system could be more suitable when ceramic brackets are bonded to enamel surface. Metal brackets can be bonded safely with both bonding systems.

Biodentine® is a bioactive calcium silicate-based material, with better strength parameters, an easier application method and a shorter setting time than mineral trioxide aggregate (MTA). The bond strength between Biodentine and the composite material is essential for the durability of the layered restoration. The objective of this study was to evaluate the bond strength of Biodentine to a resin-based composite at various acid etching times and with different adhesive strategies. In the 1st part of the experiment, the specimens were divided into 2 groups: the adhesive was applied in the total-etch (TE) and self-etch (SE) techniques. In the TE group, 37% orthophosphoric acid was applied after 30 s (TE 30) and 240 s (TE 240). In the SE group, the SE system was applied for 30 s (SE 30) and 240 s (SE 240). In the 2nd part, the SE systems Clearfil® SE Bond and Clearfil S3 Bond Plus were evaluated (the CSE and CS3 groups, respectively). In each group, the adhesive system was applied in 1 (the CSE 1 and CS3 1 subgroups) or 2 layers (the CSE 2 and CS3 2 subgroups). The specimens were subjected to a shear bond strength (SBS) test in a universal testing machine. Shear bond strength was higher after a prolonged etching procedure in the TE (TE 30: 2.51 MPa, TE 240: 9.39 MPa) and SE techniques (SE 30: 5.92 MPa, SE 240: 7.89 MPa). A statistically significant influence was detected in relation to 30 s of surface preparation time for Clearfil S3 Bond Plus (p < 0.001). Greater bond strength was revealed after the application of 1 layer of the Clearfil S3 Bond Plus single-bottle system (CS3 1: 6.42 MPa). The SBS of Biodentine to the composite depends on both the etching time and the mode of application of the adhesive systems. Higher bond strength was obtained for the SE adhesive in a shorter application time.

The aim of this study was to evaluate the effect of Er:YAG laser irradiation on the micro-shear bond strength of self-etch adhesives to the superficial dentin and the deep dentin before and after thermocycling. Superficial dentin and deep dentin surfaces were prepared by flattening of the occlusal surfaces of extracted human third molars. The deep or superficial dentin specimens were randomized into three groups according to the following surface treatments: group I (control group), group II (Er:YAG laser; 1.2 W), and group III (Er:YAG laser; 0.5 W). Clearfil SE Bond or Clearfil S3 Bond was applied to each group’s dentin surfaces. After construction of the composite blocks on the dentin surface, the micro-shear bond testing of each adhesive was performed at 24 h or after 15,000 thermal cycles. The data were analyzed using a univariate analysis of variance and Tukey’s test (p < 0.05). Laser irradiation in superficial dentin did not significantly affect bond strength after thermocycling (p > 0.05). However, deep-dentin specimens irradiated with laser showed significantly higher bond strengths than did control specimens after thermocycling (p < 0.05). Thermocycling led to significant deterioration in the bond strengths of all deep-dentin groups. The stable bond strength after thermocycling was measured for all of the superficial-dentin groups. No significant difference was found between the 0.5 and 1.2 W output power settings. In conclusion, the effect of laser irradiation on the bond strength of self-etch adhesives may be altered by the dentin depth. Regardless of the applied surface treatment, deep dentin showed significant bond degradation.

The objective of this study was to evaluate the bond strength to superficial (SU) and deep (D) dentin, accessed via apical (DA) or occlusal (DO), using One-Step adhesive system applied according to the manufacturer's instructions (C) or following deproteinization with 10% sodium hypochlorite (H) for 60s, after acid etching. Three sound extracted human molars were prepared for each experimental condition. Restorations were performed using Z100 in 2mm increments, each one being light-cured for 40s. Teeth were longitudinally sectioned to obtain stick-shaped specimens with a cross-sectional area of 0.8mm², which were submitted to bond strength test (0.6mm/min). Results obtained after statistical analysis using a two-way ANOVA (substrate vs. surface treatment) and Tukey's test were: SU (35.4 ± 12.3), DO (26.5 ± 8.5), DA (26.1 ± 10.2) following conventional surface treatment, and SU (28.82 ± 12.7), DO (24.3 ± 8.3) and DA (23.5 ± 8.5), after surface treatment using sodium hypochlorite. The interaction of the factors was not significant (p>0.05). However, the main factors were significant (p<0.05). Mean bond strength values in superficial dentin were statistically superior to deep dentin (p<0.05), although no statistically significant difference was observed between the two via of access to deep dentin (SU>DO=DA). The conventional surface treatment resulted in higher bond strength values than the sodium hypochlorite treatment (p<0.05). It was concluded: 1) bond strength values were higher in superficial dentin, 2) no difference was found between the two deep substrate preparations, and 3) the application of sodium hypochlorite following dentin acid etching may reduce bond strengths.

We sought to evaluate immediate and delayed micro-tensile bond strength of Panavia F2.0 and Multilink Sprint resin cement to superficial, deep and cervical dentin. Thirty-six freshly extracted non-carious human molars were sectioned in the mesiodistal direction to expose three different dentin regions including superficial dentin (1 mm below the dentine-enamel junction), deep dentin (1 mm above the highest pulp horn) and cervical dentin (0.5 mm above the cemento-enamel junction and 0.5 mm below the dentine-enamel junction). Resin cements were applied on dentin surfaces and composite blocks were luted under constant seating pressure. Each group was divided into three subgroups according to time intervals. Specimens were sectioned to obtain sticks of 1 mm2 in diameter and subjected to microtensile bond strength testing at a cross head speed of 1 mm/min. Both resin cements showed higher micro-tensile bond strength to superficial dentin than that to deep or cervical dentin (P < 0.001). Micro-tensile bond strengths of Panavia F2.0 were higher than those of Multilink Sprint at different dentin regions (P < 0.001). Immediate micro-tensile bond strengths were higher than those of delayed micro-tensile bond strengths for both resin cements (P < 0.001). It was concluded that resin cements with different chemical formulations and applications yield significantly different micro-tensile bond strengths to different dentin regions.

The aim of this study was to evaluate the influence of a low-viscosity bonding resin applied over a self-etching adhesive system on the microtensile bond strength (μTBS) of indirect restorations. Comparisons were made using One Up Bond F (OB) self-etching adhesive system, Single Bond (SB) one-bottle adhesive system and Scotchbond Multi Purpose Plus (SMP) bonding component. Thirty bovine incisors were extracted and decoronated at the cementoenamel junction. The labial surfaces were ground so that superficial dentin and deep dentin were exposed. The specimens were randomized to three groups (n=10): G1- OB; G2- OB + SMP; G3- SB. In G2, a layer of the SMP bonding was applied over the OB adhesive system. Indirect composite restorations were bonded using dual-cure cement under 500 g load for 5 min. The specimens were serially sectioned with a bonding area of ± 1.0 mm2 in 3 regions: enamel (E), superficial dentin (SD) and deep dentin (DD). The sticks were fixed with cyanoacrylate adhesive and submitted to μTBS test at a crosshead speed of 0.5 mm/min in a mechanical testing machine (EMIC DL 2000). The fractured specimens were examined under scanning electron microscopy to determine the failure mode. Data were analyzed by one-way ANOVA followed by Tukey's test (p<0.05). μTBS means (in MPa) were: G1/E: 15.5 ± 3.5b; G1/SD: 22.7 ± 7.6a; G1/DD: 19.4 ± 9.4a; G2/E: 15.9 ± 5.8b; G2/SD: 19.9 ± 6.9a; G2/DD: 15.3 ± 4.9a; G3/E: 23.2 ± 7.3a; G3/SD: 20.4 ± 8.2a; G3/DD: 19.1 ± 8.7a. The results showed that the use of a low viscosity bonding resin did not affect the μTBS means when associated with a self-etching adhesive system. The self-etching adhesive system was significantly more efficient in dentin than in enamel, while the one-bottle system was significantly more efficient in enamel when compared to the self-etching adhesive system.

Purpose: To evaluate the wetting ability and the microtensile bond strength of adhesive systems in various depths of dentin. Materials and Method: 48 extracted human molars cut in half in buccolingual direction. Buccal and lingual surfaces were used to obtain deep (n = 48) and superficial (n = 48) dentin. Groups were divided into 4 subgroups: Self-etch (CSE), etch&rinse (SB), multi-mode self-etch (SAU) and multimode etch&rinse (EAU) adhesive systems. 3 consecutive contact-angle measurements were obtained: T0- 3 μl drop of distilled water on dentin; T1-Droplet of the adhesive; T2- Distilled water after polymerization of the adhesive. After composite build-ups, microtensile measurements were performed. Contact angle data were analysed with analysis of variance for repeated measures. Bond strength data were analyzed by repeated measures analysis of variance, comparisons were made according to the logarithmic values (p < 0.05). Results: The difference between groups was not significant regardless of dentin depth for all measurements (p < 0.05). All groups except CSE enhanced the wetting ability of the adhesive but reduced the wetting ability of distilled water after application of the adhesive (p < 0.05). Regarding adhesive systems, the groups showed no significant difference between bond strengths to various depths of dentin except SAU (p > 0.05); in SAU, bond strength to deep dentine were significantly higher than superficial dentin (p < 0.05). Regarding adhesives’ bond strength, CSE showed significantly greater values than the other groups (p < 0.05). Conclusion: The cavity depth does not affect the bonding ability for all adhesive systems; self-etch adhesive systems might be a better choice since different adhesives may influence the wetting ability and microtensile bond strength of the dentin substrates.

Shear-bond strength of different Self-Etching adhesive systems to dentin with or without laser irradiation before photopolymerization (A comparative Study)

Influence of adhesive systems containing different functional monomers on the longevity of bond strength at different dentin depths

To compare the distribution and concentration of matrix metalloproteinases-2 (MMP-2) in different dentin depth of premolar and molar of young people. Freshly extracted human premolars and molars (aged between 20-30) were sectioned to 1.5 mm thick slices along the longitudinal axis of the tooth separately. Enamel and pulp of each slice was removed, and then the premolar and molar slices were respectively divided into two subgroups according to superficial or deep dentin and pulverized to fine powder. After dentin protein was extracted, the concentrations of MMP-2 in different tooth were detected using fluorescent microsphere immunoassay. The content of MMP-2 in superficial layer dentin of premolar was (0.022 ± 0.006) ng/mg. The content of MMP-2 in deep layer dentin of premolar was (2.087 ± 0.090) ng/mg. The content of MMP-2 in superficial layer dentin of molar was (0.336 ± 0.037) ng/mg. The content of MMP-2 in deep layer dentin of molar was (3.312 ± 0.308) ng/mg. MMP-2 exists in human coronal dentin. In the same type of teeth of young people, the concentration of MMP-2 in deep dentin was significant higher than those in superficial dentin. In the same dentin depth, the concentration of MMP-2 in molar was significant higher than those in premolar.

Susceptibility of contemporary single-bottle self-etch dentine adhesives to intrinsic water permeation