The Journal of Adhesive Dentistry, 06/2012

Purpose: To evaluate the effect of different cleaning media on the adhesion of resin cement to feldspathic ceramic after etching. Materials and Methods: The cementation surfaces of ceramic blocks (N = 20, n = 5 per group) were etched with 10% hydrofluoric acid (HF) gel for 20 s and rinsed for 60 s. They were then randomly assigned to 4 groups: G1: air-water spray+drying (control); G2: ultrasonic cleaning in distilled water for 4 min+drying; G3: ultrasonic cleaning in 99.5% acetone for 4 min+drying; G4: ultrasonic cleaning in 70% alcohol for 4 min+drying. The ceramic blocks were silanized and cemented (RelyX ARC) to the composite blocks. Subsequently, the microtensile bond strength test (µTBS) was performed. In addition, EDS analysis was made to assess the elemental composition of the conditioned and cleaned ceramic surfaces. Results: A significantly higher mean µTBS was obtained when specimens had been ultrasonically cleaned in distilled water (G2: 18.8 ± 0.4 MPa) (p < 0.05) compared to other groups (G1: 16.6 ± 0.5; G3: 16.1 ± 0.9; G4: 15.8 ± 1.4) (one-way ANOVA). EDS analysis indicated the presence of F- only in G1. Dissolved precipitates after HF etching were removed by ultrasonic cleaning. Conclusion: Cleaning the HF-etched ceramic surface ultrasonically in distilled water is recommended, instead of rinsing it with air-water spray only. Keywords: adhesion, cementation, dental materials, microtensile bond strength, ultrasonic cleaning

Purpose: To determine the effect of drying agents and adhesive solvents on the bond strength of resin composite to enamel immediately after bleaching. Material and Methods: Sixty healthy human premolars were bleached using 15% carbamide peroxide gel and randomly divided into three groups according to the immersing solutions applied immediately after bleaching: 70% alcohol, acetone, and distilled water. Each group was randomly divided into two subgroups according to the adhesives that were applied: an alcohol-based adhesive (Single Bond) and an acetone-based adhesive (One Step). By using rubber washers, composite Z100 was placed onto the enamel and shear bond strength was evaluated in a universal testing machine at a crosshead speed of 1 mm/min. The type of failure was also assessed using a stereomicroscope. The data were statistically analyzed by two-way ANOVA and Tukey's post-hoc test (α = 0.05). Fisher's Exact test was used to evaluate differences in the failure modes. Results: Statistical analysis showed that the bond strength of the distilled water groups was significantly lower than that of the other groups, but the bond strengths of the two groups where a drying agent was applied were similar to that of the unbleached group. The acetone-based adhesive (One Step) provided higher bond strength than did the alcohol-based adhesive (Single Bond) (p < 0.05). There was no interaction between the two variables (p > 0.05). Fisher's Exact test showed there was no significant difference in the failure mode of all the experimental groups (p > 0.05). Conclusion: The application of drying agents improves the bond strength of resin composite to bleached enamel. Furthermore, the acetone-based adhesive used in the study had a higher bond strength to bleached enamel than did the alcohol-based adhesive used. Keywords: bleach, drying agents, alcohol, acetone, bond strength, adhesive solvent

Purpose: To evaluate a new method of simulated pulpal pressure in vitro in comparison with the conventional one. Materials and Methods: Four adhesives were analyzed: a three-step etch-and-rinse (Scotchbond Multi-Purpose [SBMP]), a two-step etch-and-rinse (Single Bond 2 [SB]), a two-step self-etching (Clearfil SE Bond [SE]), and a one-step self-etching (Clearfil S3 [S3]) system. Restorations were built up in flat, deep dentin from extracted molars. After two methods of simulated pulpal pressure or no pulpal pressure (control groups), the samples were cut into sticks and submitted to microtensile bond strength (µTBS) testing and nanoleakage evaluation. Results were analyzed with two-way ANOVA and Tukey's test (p < 0.05). Results: In general, statistical analysis of µTBS showed SBMP>SB=SE>S3. For both methods of simulated pulpal pressure, the µTBS of SB and S3 was lower than in control groups. For SBMP and SE, the µTBS remained stable with simulated pulpal pressure. Conventional and experimental methods of simulating pulpal pressure resulted in similar µTBS (p = 1.00) and nanoleakage patterns. Silver impregnation was higher with SB and S3, especially after simulated pulpal pressure with both methods. Conclusion: The experimental simulated pulpal-pressure method tested here was similar to the conventional method and can be an alternative to it. The simplified adhesives show reduction in bond strength after simulated pulpal pressure. The multistep adhesives have stable bond strengths under simulated pulpal pressure. Therefore, the separate application of hydrophobic resin can achieve resistance to bonding deterioration after hydrostatic pressure. Keywords: pulpal pressure, dental bonding, dental adhesives, nanoleakage, dentin

Purpose: To evaluate the influence of pH cycling on microtensile bond strength (µTBS) and fracture pattern of MDPB- and fluoride-containing self-etching adhesive systems to dentin, and on the cross-sectional Knoop microhardness (CSMH) of enamel and dentin adjacent to restorations. Materials and Methods: The two-step self-etching adhesive Clearfil SE Bond (SE; Kuraray), the two-step MDPBand fluoride-containing adhesive Clearfil Protect Bond (PB; Kuraray), and the one-step fluoride-containing adhesive One-Up Bond F Plus (OU; Tokuyama) were used to bond resin composite to midcoronal dentin surfaces (for µTBS testing) or to Class V cavities (for CSMH testing). µTBS and CSMH tests were performed after a 15-day period of pH cycling or storage in artificial saliva. Results: µTBS to dentin was not affected by pH cycling or storage in artificial saliva; however, µTBS values found for PB were higher than those observed for OU. No difference existed among the µTBS values shown by PB, OU, and SE. The fracture pattern was affected by both pH cycling and adhesive system. In enamel, there was no difference in CSMH values provided by the different adhesive systems and storage media, regardless of the distance and depth from restoration. In dentin, PB and SE showed the highest CSMH values, which differed from those obtained for OU. Significantly higher CSMH values were found 100 µm from the restoration margin for all adhesive systems tested. Conclusion: The bond strength and microhardness in the vicinity of restorations were adhesive dependent, with MDPB and fluoride exerting no effect on the performance of the adhesive systems. Keywords: adhesion, bond strength, self-etching adhesive systems, pH cycling

Purpose: 1) To evaluate the marginal sealing efficacy of Biodentine at the cervical margins of approximal cavities placed in molars; 2) to evaluate and compare the use of Biodentine in combination with resin-based adhesives and a resin composite, compared with a resin-modified glass-ionomer cement (Fuji II LC). Materials and Methods: Sixty approximal cavities were prepared on mesial and distal surfaces of 30 extracted human third molars. The teeth were randomly assigned into 6 groups of 10 cavities each: (G1) Biodentine, (G2) Fuji II LC as a filling material, (G3) Biodentine as a base + Optibond Solo Plus + silane + Filtek Z250, (G4) as in G3 without silane, (G5) Biodentine as a base + Septobond SE + Filtek Z250, (G6) Fuji II LC as a base + Optibond Solo Plus + Filtek Z250. The materials were applied according to the manufacturers' instructions. Biodentine required no dentin or enamel surface conditioning treatment. The teeth were thermocycled 2500x (5°C to 55°C). The specimens were then sealed with a 1-mm window around the marginal interface. Samples were immersed in a 50% w/v silver nitrate solution and exposed to a photodeveloping solution. The teeth were embedded in resin (Sody 33) and sectioned through the restorations. The silver penetration was directly measured using a light microscope. The results were expressed as ordinal scores from 0 to 3 at cervical, interfacial, and enamel margins. The data were analyzed with the nonparametric Kruskal-Wallis, Games Howell, and Wilcoxon signed rank tests (p < 0.05). Results: No statistically significant differences were found between the 6 groups, neither for the dentin cervical margins nor for cervical lining (Biodentine or Fuji II LC)/resin composite interfaces. Statistically significant differences were observed between G5 (median score = 2.0) and the other groups (median score = 1.0) for the enamel margins. Statistically significant differences were found between enamel and dentin cervical margins in G2 (enamel median score = 1.0; dentin median score = 1.5) and G5 (enamel median score = 2.0; dentin median score = 1.0). Conclusion: Within the limits of this in vitro study, Biodentine as dentin substitute in cervical lining restorations or as a restorative material in approximal cavities when the cervical extent is under the CEJ seems to perform well without any conditioning treatment. However, the operating time is longer than when a RMGIC (Fuji II LC) is used. Keywords: Ca3SiO5-based dentin substitute, resin-modified glass-ionomer cement, microleakage

Purpose: To evaluate the dentin bond strength (BS) and sealing ability (SA) promoted by adhesive systems after 24 h or 6 months of water storage. Materials and Methods: The tested adhesive systems were: one three-step etch-and-rinse adhesive (Adper Scotchbond Multi-Purpose, SBMP) and three single-step self-etching systems (Adper Easy Bond, Bond Force, and G-Bond Plus). Bovine incisors were used for both evaluations, BS (n = 11) and SA (n = 5). To examine BS, the buccal surface was ground with SiC paper to expose a flat dentin surface. After adhesive application, a block of resin composite was incrementally built up over the bonded surface and sectioned into sticks. These bonded specimens were subjected to microtensile bond strength testing after 24 h and 6 months of water storage using a universal testing machine. For SA analysis, enamel was removed from the buccal surfaces. The teeth were connected to a device to measure the initial SA (10 psi), and the second measurement was taken after treating dentin with EDTA. Afterwards, the adhesive systems were applied to dentin and the SA was re-measured for each adhesive after 24 h and 6 months of water storage. The SA was expressed in terms of percentage of dentinal sealing. BS and SA data were submitted to two-way ANOVA and Tukey's test (α = 0.05). Results: All adhesives showed a reduction of SA after 6 months of water storage. The SA promoted by self-etching adhesives was higher than that of SBMP. No adhesive system showed a reduction of the BS after 6 months. Conclusion: Sealing ability was affected by water storage, while no changes in microtensile bond strength were observed after 6 months of water storage. The single-step self-etching systems showed greater sealing ability than did SBMP, even after 6 months of storage in water. Keywords: dentin bonding agents, bond strength, permeability, dentin

Purpose: To test whether the distance to the mass center of a buildup made of visible-light- or chemically curing composite resin bonded to dentin and cured in one increment has an influence on µTBS. Materials and Methods: In the experimental groups, one-increment visible-light (Z250) or chemically-cured (TiCore) composite-resins buildups were bonded to flattened bovine dentin surfaces. In the control groups, the same materials were bonded as separate buildups on circumscribed areas to minimize the effect of shearing polymerization contraction. Compound composite/interface/dentin specimens were trimmed out of buildups and tested in tension until detachment; the distances to the mass centers of their respective buildups were recorded as the independent variable. The correlation between µTBS and distances was tested in each group. Slopes and intercepts of regression lines (µTBS to bonded area) were compared in the experimental groups. Results: The correlation between µTBS and distances was negative and statistically significant for both experimental groups (p < 0.0001), but not for the two control groups (p > 0.34). Conclusion: In clinical situations such as direct resin veneering or resin core construction, where a first layer of a light- or chemically cured resin composite is bonded and cured on a broad surface, the µTBS of the interface decreases proportionally to the distance to the mass center of the restoration. Keywords: polymerization shrinkage, polymerization stress, resin composite, regional bond strength, microtensile testing

Purpose: This study evaluated the marginal adaptation of supragingivally relocated cervical margins. Newly developed and reference materials were compared. Materials and Methods: Eighty-eight extracted human teeth were divided into 11 groups. A standardized boxshaped cavity (4.0 mm mesiodistal width, 1.5 mm axial depth) was prepared on each tooth with the cervical margin 1.3 mm below the cementoenamel junction. Seven different restorative materials (Filtek Silorane [Sil], Clearfil AP-X [APX], Clearfil Majesty Posterior [CMP], Clearfil Majesty Flow [CMFlow], RelyX Unicem [RelyX], SDR [SDR], Vertise Flow [VertFlow]) were applied in a layer of 1.5 mm, combined with different adhesive systems (Filtek Silorane Primer + Bond [SilPB], Clearfil Profect Bond [ClePB], Filtek Silorane Bond [SilB]). No indirect restorations (ie, inlays/onlays) were placed on these restorations. SEM analysis was performed to evaluate marginal adaptation in enamel and dentin. The results were subjected to statistical analysis by Kruskal Wallis and Duncan post-hoc tests. Results: In both dentin and enamel, statistically significant differences were present between groups (p < 0.001). In enamel, the lowest percentage of continuous margin was observed for SilPB/CMP, SilPB/APX, and ClePB/SDR, while SilPB/Sil exhibited the highest percentage of continuous margin, although this was not statistically different from other groups except for SilPB/CMP, SilPB/APX, and ClePB/SDR. In dentin, a higher percentage of continuous margin was observed for all materials than in enamel (p < 0.002). Statistically significant differences were found between ClePB/SilB/Sil, ClePB/SDR, and RelyX, SilPB/APX, ClePB/APX, and ClePB/Sil. ClePB/Sil showed the lowest marginal adaptation. Considering the overall marginal length, the best marginal adaptation was exhibited by ClePB/SilB/Sil, followed by SilPB/Sil, ClePB/SDR, and ClePB/CMP. Conclusion: Marginal adaptation of supragingivally relocated cervical margins is significantly influenced by the materials used. Keywords: subgingival, marginal adaptation, silorane, relocation, inlays, onlays, resin composite, resin coating

Purpose: To investigate the influence of caries infiltrant application on the shear bond strength of different adhesives on sound and demineralized enamel. Materials and Methods: Sound and artificially demineralized (14 days, acidic buffer, pH 5.0) bovine enamel specimens were treated with a caries infiltrant (Icon, DMG), three different commercial adhesives (unfilled etchand- rinse adhesive: Heliobond, Ivoclar Vivadent; filled etch-and-rinse adhesive: Optibond FL, Kerr; or self-etching adhesive: iBOND Self Etch, Heraeus Kulzer) or a combination of caries infiltrant and adhesive. The shear bond strength of a nanohybrid composite was analyzed after thermocycling (5000x, 5° to 55°C) at a crosshead speed of 1 mm/min. Failure mode was inspected under a stereomicroscope at 25X magnification. Results: In both sound and demineralized enamel, the shear bond strength of the caries infiltrant was not significantly different from the etch-and-rinse adhesives, while the self-etching adhesive showed significantly lower values compared to all other groups. Pretreatment with the caries infiltrant significantly increased the bond strength of the self-etching adhesive in both substrates and of the filled etch-and-rinse adhesive in demineralized enamel. While shear bond strength was not significantly different between the two substrates, cohesive failures were more likely to occur in demineralized than sound specimens. Conclusion: The shear bond strength of the caries infiltrant was similar to the etch-and-rinse adhesives. The caries infiltrant did not impair bonding to sound or demineralized enamel, and even increased adhesion of the selfetching agent. Keywords: enamel, demineralization, caries infiltrant, adhesive, shear bond strength

Purpose: To evaluate the influence of a 2% chlorhexidine solution (CHX) on the bond strength and nanoleakage of two self-etching adhesive systems on demineralized dentin over a 12-month period. Materials and Methods: The middle dentin from sound third molars was exposed and demineralized in vitro. Twelve groups were formed using different adhesive systems (Clearfil Protect Bond [PB], Clearfil SE Bond [SE]) dentin treatment (with or without CHX application), and water-storage times (24 h, 6 and 12 months). Composite resin cylinders were bonded to the prepared dentin, and these specimens underwent microshear bond strength (µSBS) testing and nanoleakage evaluation. µSBS data were submitted to a three-way ANOVA and Tukey's test. The failure mode and nanoleakage were analyzed descriptively by score. Results: There was a statistically significant interaction only between the adhesive system and CHX, and adhesive system and water-storage times. SE showed the lowest µSBS just at 24 h water-storage time regardless of CHX. A significant decrease in µSBS values after 6 months of water storage occurred in all of the groups and was maintained until 12 months. Adhesive failure increased with storage time. All groups showed nanoleakage at the resin/dentin interfaces and an increased silver deposition was noticed after 6 and 12 months of water storage. The highest percentages of nanoleakage were found in CHX groups. Conclusion: CHX did not interfere with µSBS values for either self-etching adhesive system, but water storage did. Bond strength decreased for both adhesive systems after 6 and 12 months, regardless of CHX application. Nanoleakage increased with water-storage time and with CHX application. Keywords: microshear bond strength, chlorhexidine, adhesive systems, bond degradation, nanoleakage, cariesaffected dentin

Purpose: The aim of this blinded, randomized, prospective long-term study was to evaluate the clinical performance of the two-step self-etching adhesive AdheSE (AS, Ivoclar Vivadent) compared to the etch-and-rinse adhesive system Excite (EX, Ivoclar Vivadent) in combination with the hybrid resin composite Tetric Ceram HB (Ivoclar Vivadent) for Class I and II restorations. Materials and Methods: In accordance with a split mouth design, 50 patients received 100 restorations in premolars and molars. The restorations were assigned at random to the self-etching (AS) or the etch-and-rinse (EX) group. Each restoration was scored according to the modified Ryge criteria at baseline and after 6, 12, 24 and 48 months. Epoxy resin replicas of 60 restorations were made at each observation period for an additional SEM analysis of the occlusal margins. Results: After 4 years, 60 of 100 restorations could be evaluated. The cumulative survival rate for group EX was 100% and for group AS 96.7%. One restoration in group AS had failed due to marginal gap formation. For the criterion marginal adaption in group AS, significantly more bravo ratings (30%) were observed after 4 years compared to group EX (6.7%) (p < 0.05; Mann-Whitney U-test). The results of the SEM margin analysis revealed no significant differences between groups AS and EX (Mann-Whitney U-test; p > 0.05). Conclusion: Both adhesive systems performed satisfactorily over the four-year observation period. A significant deterioration over time was found for the criterion marginal adaption in AdheSE. Keywords: clinical study, self-etchinging adhesive, flowable composite, Ryge criteria, composite resin