Bond strength of a total-etch and two self-etch adhesives to dentin with and without intermediate flowable liner.

PURPOSE: To evaluate the effect of flowable resin composite application on the microtensile bond strength of a total-etch and two self-etch adhesive systems to dentin. METHODS: Occlusal surfaces of 30 human third molars were ground to obtain flat dentin surfaces. One of the following adhesive systems was applied to the dentin surface following manufacturers' instructions: Admira Bond, Futurabond DC and Clearfil SE Bond. For each adhesive, half of the specimens received a layer of flowable composite (Amaris Flow) applied into dentin and light-cured (experimental groups). The other teeth received no liner and served as control group. For all teeth, resin composite (Amaris) was applied in 2 mm thickness to form a crown segment 5-6 mm height and each increment was light-cured. The restored teeth were stored in water at 37 degrees C for 24 hours. Each tooth was serially sectioned in a longitudinal direction in order to obtain several bonded slabs (1.0 mm2 in cross-section). Each slab was attached to the set-up by their lateral sides and placed in a universal testing machine. Tensile load was applied at cross-head speed of 0.5 mm/minute until failure. Data were analyzed by two-way ANOVA and Tukey's test at 5% significance level. RESULTS: Placement of a low-viscosity resin after adhesive application increased the microtensile bond strength for all tested adhesive systems. However, such increase was not significant (P > 0.05). The percentage of cohesive failure was increased in specimens with flowable resin liner.

Efficacy of microtensile versus microshear bond testing for evaluation of bond strength of dental adhesive systems to enamel.

OBJECTIVE: The aim of the study was to evaluate the efficacy of the microtensile bond test (microTBS) and the microshear bond test (microSBS) in ranking four dental adhesives according to bond strength to enamel and identify the modes of failure involved. MATERIALS AND METHODS: Forty-four caries-free human molars were randomly assigned to one of two bond strength testing methods: 20 teeth were used for microTBS test and 24 teeth for microSBS test. Flat enamel surfaces were created by wet grinding. Four adhesive systems were applied to the ground enamel surfaces; a two-step self-etch (Clearfil SE Bond, SEB), two all-in-one self-etch (Adper Prompt L-Pop, APL; Hybrid Bond, HB) and a two-step etch-and-rinse (Adper Single Bond, ASB). Resin composite (Z100) was applied over the adhesive. The microTBS and microSBS were determined after 24h of storage in water at 37 degrees C. The mode of failure was determined by light microscope and SEM. Data was analyzed with ANOVA, Tukey's and Chi-square tests. RESULTS: microTBS test ranked the adhesives as follows: SEB=ASB=APL>HB, while microSBS test ranked the adhesives as follows: ASB>SEB=APL>HB. The highest percentage failure mode with microTBS testing was cohesive in enamel or at the DEJ: SEB (95%), APL (65%) and ASB (65%). As for HB, adhesive failure (95%) was the common finding. The predominant failure mode in case of the microSBS was adhesive (APL 50%, SEB 58.3%, ASB 75% and HB 91.7%). SIGNIFICANCE: Ranking appears to be test-dependant and microSBS test appears to be more accurate in differentiating among the stronger adhesives.

Effect of long-term water aging on microtensile bond strength of self-etch adhesives to dentin.

PURPOSE: To evaluate the effect of water storage on the microtensile dentin bond strength of one total-etch and four self-etching adhesives to dentin. METHODS: The adhesive materials were: one total-etch adhesive (Admira Bond) and four self-etch adhesives (Clearfil S tri Bond, Hybrid Bond, Futurabond NR, Adhe SE). Freshly extracted human third molar teeth were used. For each tooth, dentin was exposed on the occlusal surface by cutting with an Isomet saw and the remaining part was mounted in a plastic ring using dental stone. After adhesive application, a composite resin (Grandio) was placed in 5-6 mm height to form a crown segment. For each tested adhesive, two test procedures (n=6 teeth) were carried out. Procedure A: the teeth were stored in water for 24 hours, and then sectioned longitudinally, buccolingually and mesiodistally to get rectangular beams of 1 +/- 0.1 mm thickness on which a micro-tensile test was carried out. Procedure B: The specimens were stored in water at 37 degrees C for 3 years before sectioning and microtensile testing. During microtensile testing the beams were placed in a universal testing machine and load was applied at cross-head speed of 0.5 mm/minute. RESULTS: For the 24-hour water storage groups, there was no significant difference in the bond strength between the different adhesives. After 3 years of water storage, the bond strength of all self-etch adhesives was significantly reduced compared to the control groups (24 hours). In contrast, the bond strength of Admira Bond was not significantly reduced.

Bond efficacy and interface morphology of self-etching adhesives to ground enamel.

PURPOSE: This study compared the microshear bond strengths to ground enamel of three one-step self-etching adhesive systems, a self-etching primer system and an etch-and-rinse adhesive system. MATERIALS AND METHODS: Three self-etching adhesives, Futurabond DC (Voco), Clearfil S Tri Bond (Kuraray) and Hybrid bond (Sun-Medical), a self-etching primer, Clearfil SE Bond (Kuraray), and an etch-and-rinse system, Admira Bond (Voco), were selected. Thirty human molars were used. The root of each tooth was removed and the crown was sectioned into halves. The convex enamel surfaces were reduced by polishing on silicone paper to prepare a flat surface. The bonding systems were applied on this surface. Prior to adhesive curing, a hollow cylinder (2.0 mm height/0.75 mm internal diameter) was placed on the treated surfaces. A resin composite was then inserted into the tube and cured. After water storage for 24 h, the tube was removed and shear bond strength was determined in a universal testing machine at a crosshead speed of 0.5 mm/min. The results were analyzed with ANOVA and the Tukey.-Kramer test at a 59 degrees confidence level. The enamel of five additional teeth was ground, and the etching component of each adhesive was applied and removed with absolute ethanol instead of being light cured. These teeth and selected fractured surfaces were examined by SEM. RESULTS: Adhesion to ground enamel of the Futurabond DC (25 +/- 3.5 MPa) and Clearfil SE Bond (23 +/- 2.9 MPa) self-etching systems was not significantly different from the etch-and-rinse system Admira Bond (27 +/- 2.3 MPa). The two self-etching adhesives Clearfil S Tri bond and Hybrid Bond demonstrated significantly lower bond strengths (14 +/- 1.4 MPa; 11 +/- 1.9 MPa) with no significant differences between them (p < 0.05). CONCLUSION: Bond strengths to ground enamel of self-etching adhesive systems are dependent on the type of adhesive system. Some of the new adhesive systems showed bond strength values comparable to that of etch-and-rinse systems. There was no correlation between bond strength and morphological changes in enamel.

Two-year water degradation of self-etching adhesives bonded to bur ground enamel.

To evaluate the effect of water storage on the microshear bond strength to ground enamel of three "all-in-one" self-etch adhesives: Futurabond DC, Clearfil S Tri Bond and Hybrid bond; a self-etching primer; Clearfil SE Bond and an etch-and-rinse adhesive system, Admira Bond. Sixty human molars were used. The root of each tooth was removed and the crown was sectioned into two halves. The convex enamel surfaces were reduced by polishing on silicon paper to prepare a flat surface that was roughened with a parallel-sided diamond bur with abundant water for five seconds. The bonding systems were applied on this surface. Prior to adhesive curing, a hollow cylinder (2.0 mm in height/0.75 mm in internal diameter) was placed on the treated surfaces and cured. A resin composite was then inserted into the tube and cured. For each adhesive, two procedures were carried out: A--the specimens were kept in water for 24 hours, then the tube was removed and the microshear bond strength was determined in a universal testing machine at a crosshead speed of 0.5 mm/minute; B--the specimens were stored in water for two-years before microshear testing. The fractured surface of the bonded specimens after each test procedure was examined by SEM. For the 24-hour control, there was no significant difference in bond strength between the tested adhesives. After two years of water storage, the bond strength of Admira Bond, Clearfil SE Bond and Futurabond DC decreased, but the reduction was not significantly different from that of 24 hours. For Clearfil S Tri Bond and Hybrid Bond, the bond strengths were significantly reduced compared to their 24-hour results.

Clinical evaluation of a self-etch adhesive in non-carious cervical lesions.

PURPOSE: To evaluate the clinical performance of a self-etching adhesive in Class V non-carious lesions with and without acid etching procedures. METHODS: A total of 125 Class V non-carious cervical lesions (NCCL) with incisal or occlusal margins in enamel and gingival margins in dentin/cementum were selected and restored with Clearfil SE Bond self-etch adhesive and Clearfil APX resin composite. All cavities were restored using two techniques; after etching the whole cavity for 20 seconds and without acid etching (control). The restorations were evaluated at baseline, 1- and 2-year using modified USPHS criteria. RESULTS: No loss of restorations was recorded after 1 and 2 years for the two restorative techniques. There was no significant difference between the baseline and 2-year results for any of the tested technique. However, restorations made after acid etching showed less marginal discoloration at the enamel margins.

Effect of hydrostatic pulpal water pressure on microtensile bond strength of self-etch adhesives to dentin.

PURPOSE: To evaluate the effect of pulpal pressure on the microtensile bond strength of four self-etch adhesives to dentin. A total-etch adhesive was added for comparison. METHODS: 60 freshly extracted human third molars were selected. For each tooth, the root was removed below the cemento-enamel junction. A second parallel section was made to remove the coronal enamel to form a crown segment. The root portion of the resulting crown segment was cemented to a Plexiglas platform using cyanoacrylate cement. The crown segment was then connected with a plastic tube to a water column to produce a pressure of 20 cm H2O at the prepared dentin surface of the crown segment. The adhesive materials were: a total-etch adhesive (Scotchbond 1) and four self-etch adhesives (Clearfil SE Bond, Hybrid Bond, Futurabond NR, and AdheSE Bond). The tested adhesives were applied to the dentin surface in three test procedures: applied to dentin without pulpal pressure, applied to dentin with pulpal pressure for 24 hours, and applied to dentin with pulpal pressure and the pressure was maintained for 6 months during storage. Grandio resin composite was placed in 3-4 layers to a height of 5-6 mm to form a crown segment. For bond strength measurement, the composite-dentin segment was removed from the Plexiglas. This segment was then sectioned to prepare the specimens for microtensile bond measurement. RESULTS: None of the tested adhesives showed bond strength reduction when applied to dentin supplied with water pressure. After 6 months of pulpal pressure, Scotchbond 1, Clearfil SE Bond and AdheSE Bond showed significant reduction in bond strength (P < 0.05). In contrast, Futurabond NR and Hybrid Bond were not significantly affected.

Four-year water degradation of a total-etch and two self-etching adhesives bonded to dentin.

OBJECTIVES: To evaluate effect of direct and indirect water storage on the microtensile dentin bond strength of one total-etch and two self-etching adhesives. METHODS: The adhesive materials were: one total-etch adhesive; 'Admira Bond' and two self-etch adhesives; 'Clearfil SE Bond' and 'Hybrid Bond'. Freshly extracted human third molar teeth were used. In each tooth, a Class I cavity (4mmx4mm) was prepared in the occlusal surface with the pulpal floor extending approximately 1mm into dentin. The teeth were divided into three groups (n=18). Each group was restored with the resin composite 'Clearfil APX' using one of the tested adhesives. For each experimental group 3 test procedures (n=6) were carried out: Procedure A: the teeth were stored in water for 24h (control), then sectioned longitudinally, buccolingually and mesiodistally to get rectangular slabs of 1.0-1.2mm thickness on which a microtensile test was carried out. Procedure B: the teeth were also sectioned; however, the slabs were stored in water at 37 degrees C for 4 years before microtensile testing (direct water storage). Procedure C: the teeth were kept in water at 37 degrees C 4 years before sectioning and microtensile testing (Indirect water storage). During microtensile testing the slabs were placed in a universal testing machine and load was applied at cross-head speed of 0.5mm/min. RESULTS: For the 24h control, there was no significant difference in bond strength between the three tested adhesives. After 4 years of indirect water storage, the bond strength decreased but the reduction was not significantly different from those of 24h. After 4 years of direct water storage, the bond strengths of all tested adhesives were significantly reduced compared to their 24h results. CONCLUSION: All the tested adhesives showed no reduction in bond strength after indirect water exposure for 4 years. After 4-year direct water exposure, the bond produced by all tested adhesives was unable to resist deterioration.

Morphological characterization of the interface between self-etching adhesives and vital dentin.

PURPOSE: To evaluate the in vivo interface between one total-etch and two self-etching adhesives to dentin. METHODS: Two self-etching primers, SE Bond and Hybrid Bond and one total-etch adhesive, Admira Bond, were applied in vivo to flat dentin surfaces on human teeth scheduled for extraction. After adhesive application and curing, a thin layer of resin composite was applied and cured. The teeth were extracted immediately after adhesive application. All samples were split fractured along their long axes. Half of the samples were decalcified and deproteinized to permit visualization of the hybrid layer. The other halves were completely dissolved to observe the morphology of resin tags. RESULTS: The total-etch system Admira Bond showed a thick hybrid layer and long resin tags, while SE Bond showed very thin hybrid layer with short resin tags. The findings of Hybrid Bond were similar to that of Admira Bond.

Influence of thermal and mechanical load cycling on the microtensile bond strength of self-etching adhesives.

PURPOSE: To evaluate the influence of thermal and mechanical load cycling on the microtensile dentin bond strength of two self-etching and one total-etch adhesives. METHODS: The adhesive materials were: a two-step self-etch adhesive (Clearfil SE Bond), a one-step self-etch adhesive (Hybrid Bond), and a total-etch one-step adhesive (Admira Bond). Sixty freshly extracted human third molars were used. In each tooth, a Class I cavity (4 x 4 mm) was prepared in the occlusal surface with the pulpal floor extending about 1 mm into dentin. The teeth were divided into three groups (n=20). Each group was restored with the resin composite Clearfil APX using one of the adhesives. After restoration, 10 teeth in each group were thermocycled between 5 degrees C and 55 degrees C, (dwell time 3 minutes, 5,000 cycles). The same teeth were then mounted in a fatigue loading machine to receive an intermittent load of 125 N at 52 cycles/minute for 4,000 cycles. Subsequently, each tooth was sectioned longitudinally, bucco-lingually and mesio-distally to get rectangular slabs 1-1.2 mm in thickness for the microtensile test. Each slab was then placed in a universal testing machine and tensile load was applied at a cross-head speed of 0.05 mm/minute. RESULTS: Without loading procedures, there was no significant difference in the bond strength of the tested adhesives. In contrast to Admira Bond and Clearfil SE Bond, fatigue loading resulted in a significant reduction of the bond strength for Hybrid Bond when compared to the unloaded restorations.

Clinical performance of a self-etch adhesive in Class V restorations made with and without acid etching.

OBJECTIVES: To evaluate the clinical performance of a self-etching adhesive in Class V carious lesions with and without acid etching procedures. METHODS: A total of 183 Class V carious cavities with incisal margins in enamel and gingival margins in cementum were selected and restored with Futurabond NR self-etch adhesive and resin composite Grandio. Restorations were made using three different techniques; after etching of the enamel, after etching the whole cavity for 20s and without acid etching (control). The restorations were evaluated at baseline, 1 and 2 years using USPHS criteria. RESULTS: No loss of restorations was recorded after 1 and 2 years for all the three restorative techniques. There was no significant difference between the baseline and 2-year results for any of the tested technique. However, restorations made after acid etching showed less marginal discoloration at the enamel margins. CONCLUSION: The clinical performance of Futurabond NR self-etch adhesive was excellent after 2 years. Acid etching of the enamel margin or the whole cavity did not improve the overall quality of the restorations, but displayed less marginal discoloration.

The effect of direct and indirect water storage on the microtensile dentin bond strength of a total-etch and two self-etching adhesives.

PURPOSE: To evaluate the effect of direct and indirect water storage on the microtensile dentin bond strength of one total-etch and two self-etching adhesives. METHODS: The adhesive materials were: one total-etch adhesive; Admira Bond and two self-etch adhesives; Clearfil SE Bond and Hybrid Bond. Freshly extracted human third molar teeth were used. In each tooth, a Class I cavity (4 x 4 mm) was prepared in the occlusal surface with the pulpal floor extending approximately 1 mm into dentin. The teeth were divided into three groups (n = 12). Each group was restored with the resin composite Clearfil APX using one of the tested adhesives. For each experimental group three test procedures (n = 10) were carried out: Procedure A: the teeth were stored in water for 24 hours, then sectioned longitudinally, buccolingually and mesiodistally to get rectangular slabs of 1.0 - 1.2 mm thickness on which a microtensile test was carried out; Procedure B: the teeth were also sectioned, however the slabs were stored in water at 37 degrees C for 1 year before microtensile testing; Procedure C: the teeth were kept in water at 37 degrees C for 1 year before sectioning and microtensile testing. During microtensile testing the slabs were placed in a universal testing machine and load was applied at a cross-head speed of 0.5 mm/minute. RESULTS: For the 24-hour water storage groups there was no significant difference in bond strength between the three adhesives. After 1 year of indirect water storage, the bond strength decreased but the reduction was not significantly different from those of 24 hours. After 1 year of direct water storage, the mean bond strengths of Admira Bond and Hybrid Bond were significantly reduced compared to their 24-hour results. In contrast the average value of Clearfil SE Bond was not significantly affected.

Clinical evaluation of self-etch adhesives in Class V non-carious lesions.

PURPOSE: To evaluate the clinical performance of two self-etching and one total-etch adhesives in Class V non-carious cervical lesions (NCCL). METHODS: Two self-etching primers, Clearfil SE Bond and Hybrid Bond, and one total etch adhesive, Admira Bond, were placed in 195 NCCL. Restorations were evaluated at baseline, 1 and 2 years using the USPHS criteria. RESULTS: No restoration was lost after 1 and 2 years for all materials. There was no significant difference between the baseline and 2-year results for Admira Bond and Clearfil SE Bond restorations. In contrast, Hybrid Bond restorations showed significant deterioration in marginal adaptation and cavosurface marginal discoloration after 2 years. Also, there was no significant difference between Admira Bond and Clearfil SE Bond at each recall period.

Morphological characterization of single bottle adhesives and vital dentin interface.

PURPOSE: To evaluate the in vivo interfacial relationship between four one-bottle adhesives and dentin. MATERIAL AND METHODS: Four one-bottle adhesives (Scotchbond 1, Syntac SC, One-Step and Prime & Bond 2.1) were applied on flat dentin surfaces on human anterior teeth scheduled for extraction for dentures. A three-step adhesive system (Scotchbond Multi-Purpose) was used as a control. After adhesive application, a thin layer of composite was applied and light cured. The teeth were extracted immediately after resin curing. All samples were split fractured along their long axis. Half of the samples were deproteinized and decalcified at the interface in order to visualize the hybrid layer. The other halves were completely dissolved to observe the morphology of the resin tags. RESULTS: All the one-bottle adhesives produced hybrid layers and resin tags at the dentin-resin interface. The three-step adhesive showed the same interfacial image but with a thicker hybrid layer and longer resin tags.