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Effect of riboflavin on bond stability: A 1-year study
d e n t a l m a t e r i a l s 2 6 S ( 2 0 1 0 ) e1–e84
observed in the PAE group with un-etched prismless enamel in the depth of the fissures. The Kruskal–Wallis test demonstrated no statistically significant difference among the groups (P = 0.43). Conclusions: Despite the enamel etching pattern being similar for all SEAs used, two-step self-etching systems containing phosphate derivative monomers were the most efficient self-etching agents with a more homogeneous and regular pattern of demineralization when compared to the traditional PAE. doi:10.1016/j.dental.2010.08.016 9 Replacing HEMA for surfactant dimethacrylate monomers in self-etching adhesive formulations S. Chersoni 1 , C.H. Zanchi 2 , E.A. Münchow 2 , F.A. Ogliari 2 , C. Prati 1 , M.G. Gandolfi 1 , E. Piva 2 , F.F. Demarco 2 1 2
University of Bologna, Italy Federal University of Pelotas, Brazil
Objectives: To evaluate the influence of surfactant dimethacrylates (SD) on the resin-to-dentin microtensile bond strength (TBS) and to characterize the interfacial micromorphology of hybrid layer of the experimental HEMA-free self-etching systems. Materials and methods: Five experimental HEMA-free two-step self-etching systems containing different surfactant dimetacrylates (SD) (Bis-EMA 10, Bis-EMA 30, PEG 400, PEG 1000 and PEG 400 UDMA) and a HEMA-containing system (control) were formulated. Sixty bovine incisors allocated into six groups had their superficial coronal dentin exposed. Each experimental adhesive system was applied and resin composite restorations were incrementally built up. After 24 h, restored teeth were sectioned to obtain 24 sticks per group with cross-sectional area of 0.5 mm2 . Thereafter, the specimens were subjected to the TBS test. Data (MPa) were analyzed by one-way ANOVA and Tukey’s test. Analysis of the adhesive–dentin interfaces was performed through scanning electron microscopy (SEM). Results: The adhesive system formulated with PEG 400 UDMA produced TBS similar to the HEMA-containing group and statistically higher than the HEMA-free groups. Additionally, similar failure percentages were observed in the PEG 400 UDMA and the control group. The lowest TBS was observed with Bis-EMA 30 with predominance of the adhesive failures. In the SEM analysis, all the adhesives systems presented similar partially demineralized hybrid layer (1.5–3.0 m thickness) with well-formed resin tags. Conclusions: All the adhesives systems presented similar partially demineralized hybrid layer with well-formed resin tags. All SD presented reasonable initial TBS, with the PEG 400 UDMA being a promising monomer to be considered as a HEMA substitute in adhesive systems compositions. doi:10.1016/j.dental.2010.08.017
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10 Effect of riboflavin on bond stability: A 1-year study A. Cova 1 , F. Nato 2 , A. Mazzoni 1 , A. Ruggeri 1 , C. Prati 1 , L. Breschi 3 1
University of Bologna, Italy University of Urbino, Italy 3 University of Trieste, Italy 2
Objectives: The stability of the dentin collagen network is crucial for bonding effectiveness over time. Previous studies reported the success of cross-linkers in adequately stabilize the dentin collagen network preventing its degradation. Thus, the aim of this study was to assay the stability of the dentin/adhesive interface created by a 2-step etch-and-rinse adhesive system applied with or without 0.1% riboflavin pretreatment. Materials and methods: Middle/deep dentin was exposed from human molars and etched with 35% phosphoric acid for 15 s. Specimens were then assigned to: Group 1, dentin was treated with 0.1% riboflavin (water solution) and exposed to ultraviolet type A radiation for 2 min, then XP Bond (Dentsply DeTrey GmbH, Konstanz, German) was applied; Group 2, XP Bond was applied on untreated etched dentin (control). Specimens were processed for microtensile bond strength analysis in accordance with the non-trimming technique and pulled to failure after 24 h, 6 months or 1 year of storage in artificial saliva at 37 ◦ C. Data were analyzed with two-way ANOVA and Tukey post hoc test (p < 0.05). Interfacial nanoleakage evaluation was performed at light microscope and TEM. Results: The use of ultraviolet-activated riboflavin before XP-Bond application increased immediate bond strength compared to controls (Group 1: 44.4 ± 10.4 MPa vs. Group 2: 37.3 ± 10.3 MPa, respectively; p < 0.05). After storage (either 6 months or 1 year) riboflavin-treated specimens confirmed the findings revealing higher bond strength compared to controls (6 months: 35.6 ± 11.2 MPa vs. 22.0 ± 7.0 MPa, respectively, p < 0.05; 1 year: 30.9 ± 12.2 MPa and 17.7 ± 9.1 MPa, respectively, p < 0.05). Interfacial nanoleakage expression along XP-Bond bonded interfaces decreased on riboflavin-treated specimens compared to controls irrespective from storage. Conclusions: The use of ultraviolet-activated riboflavin as experimental cross-linker on etched dentin surfaces before the application of a 2-step etch-and-rinse adhesive increased bond strength and reduced interfacial nanoleakage expression at 6 months and 1 year of artificial aging. These data can be related to increased dentin collagen cross-linking due to riboflavin application. Further studies are needed to support the use of riboflavin in vivo. doi:10.1016/j.dental.2010.08.018
observed in the PAE group with un-etched prismless enamel in the depth of the fissures. The Kruskal–Wallis test demonstrated no statistically significant difference among the groups (P = 0.43). Conclusions: Despite the enamel etching pattern being similar for all SEAs used, two-step self-etching systems containing phosphate derivative monomers were the most efficient self-etching agents with a more homogeneous and regular pattern of demineralization when compared to the traditional PAE. doi:10.1016/j.dental.2010.08.016 9 Replacing HEMA for surfactant dimethacrylate monomers in self-etching adhesive formulations S. Chersoni 1 , C.H. Zanchi 2 , E.A. Münchow 2 , F.A. Ogliari 2 , C. Prati 1 , M.G. Gandolfi 1 , E. Piva 2 , F.F. Demarco 2 1 2
University of Bologna, Italy Federal University of Pelotas, Brazil
Objectives: To evaluate the influence of surfactant dimethacrylates (SD) on the resin-to-dentin microtensile bond strength (TBS) and to characterize the interfacial micromorphology of hybrid layer of the experimental HEMA-free self-etching systems. Materials and methods: Five experimental HEMA-free two-step self-etching systems containing different surfactant dimetacrylates (SD) (Bis-EMA 10, Bis-EMA 30, PEG 400, PEG 1000 and PEG 400 UDMA) and a HEMA-containing system (control) were formulated. Sixty bovine incisors allocated into six groups had their superficial coronal dentin exposed. Each experimental adhesive system was applied and resin composite restorations were incrementally built up. After 24 h, restored teeth were sectioned to obtain 24 sticks per group with cross-sectional area of 0.5 mm2 . Thereafter, the specimens were subjected to the TBS test. Data (MPa) were analyzed by one-way ANOVA and Tukey’s test. Analysis of the adhesive–dentin interfaces was performed through scanning electron microscopy (SEM). Results: The adhesive system formulated with PEG 400 UDMA produced TBS similar to the HEMA-containing group and statistically higher than the HEMA-free groups. Additionally, similar failure percentages were observed in the PEG 400 UDMA and the control group. The lowest TBS was observed with Bis-EMA 30 with predominance of the adhesive failures. In the SEM analysis, all the adhesives systems presented similar partially demineralized hybrid layer (1.5–3.0 m thickness) with well-formed resin tags. Conclusions: All the adhesives systems presented similar partially demineralized hybrid layer with well-formed resin tags. All SD presented reasonable initial TBS, with the PEG 400 UDMA being a promising monomer to be considered as a HEMA substitute in adhesive systems compositions. doi:10.1016/j.dental.2010.08.017
e5
10 Effect of riboflavin on bond stability: A 1-year study A. Cova 1 , F. Nato 2 , A. Mazzoni 1 , A. Ruggeri 1 , C. Prati 1 , L. Breschi 3 1
University of Bologna, Italy University of Urbino, Italy 3 University of Trieste, Italy 2
Objectives: The stability of the dentin collagen network is crucial for bonding effectiveness over time. Previous studies reported the success of cross-linkers in adequately stabilize the dentin collagen network preventing its degradation. Thus, the aim of this study was to assay the stability of the dentin/adhesive interface created by a 2-step etch-and-rinse adhesive system applied with or without 0.1% riboflavin pretreatment. Materials and methods: Middle/deep dentin was exposed from human molars and etched with 35% phosphoric acid for 15 s. Specimens were then assigned to: Group 1, dentin was treated with 0.1% riboflavin (water solution) and exposed to ultraviolet type A radiation for 2 min, then XP Bond (Dentsply DeTrey GmbH, Konstanz, German) was applied; Group 2, XP Bond was applied on untreated etched dentin (control). Specimens were processed for microtensile bond strength analysis in accordance with the non-trimming technique and pulled to failure after 24 h, 6 months or 1 year of storage in artificial saliva at 37 ◦ C. Data were analyzed with two-way ANOVA and Tukey post hoc test (p < 0.05). Interfacial nanoleakage evaluation was performed at light microscope and TEM. Results: The use of ultraviolet-activated riboflavin before XP-Bond application increased immediate bond strength compared to controls (Group 1: 44.4 ± 10.4 MPa vs. Group 2: 37.3 ± 10.3 MPa, respectively; p < 0.05). After storage (either 6 months or 1 year) riboflavin-treated specimens confirmed the findings revealing higher bond strength compared to controls (6 months: 35.6 ± 11.2 MPa vs. 22.0 ± 7.0 MPa, respectively, p < 0.05; 1 year: 30.9 ± 12.2 MPa and 17.7 ± 9.1 MPa, respectively, p < 0.05). Interfacial nanoleakage expression along XP-Bond bonded interfaces decreased on riboflavin-treated specimens compared to controls irrespective from storage. Conclusions: The use of ultraviolet-activated riboflavin as experimental cross-linker on etched dentin surfaces before the application of a 2-step etch-and-rinse adhesive increased bond strength and reduced interfacial nanoleakage expression at 6 months and 1 year of artificial aging. These data can be related to increased dentin collagen cross-linking due to riboflavin application. Further studies are needed to support the use of riboflavin in vivo. doi:10.1016/j.dental.2010.08.018