Microtensile bond strengths of composite to dentin treated with desensitizer products

Purpose: This study was designed to analyze the influence of desensitizing procedures on dentin bond strength. Materials and Methods: Forty bovine incisors were used, divided into four groups (n = 10): G1: control; G2: Gluma Desensitizer (Heraeus Kulzer); G3: Oxa-Gel (Art-Dent); G4: low-intensity laser (MMOptics). The buccal surface was wet ground flat with 180-, 400- and 600-grit silicon carbide abrasive paper to expose midcoronal dentin and create a uniform surface. After the application of the desensitizing agents to the exposed dentin, the specimens were etched with 35% phosphoric acid for 30 s, and an adhesive (Single Bond) was applied and light cured. A 4-mm high crown of composite resin (Filtek Z250) was then built up. Specimens were trimmed to an hourglass shape with cross sections of 1 mm(2). Each specimen was individually fractured by a microtensile testing machine at a crosshead speed of 0.5 mm/min. The data, recorded in MPa, were analyzed with one-way ANOVA and the Duncan test (p = 0.05). Results: Specimens treated with dentin desensitizers (except Gluma) yielded significantly lower mean bond strengths than nontreated control specimens. The mean values in MPa ( +/- SD) were: G1: 13.4 (6.2); G2: 13.2 (4.8); G3: 7.15 (4.3); G4: 7.21 (4.6). Conclusions: Among the desensitizing agents studied, only Gluma Desensitizer did not detrimentally influence the bond strength values. It is a useful material for dentin desensitization.82859

Effect of two different restorative techniques using resin-based composites on microleakage

Purpose: To evaluate in vitro the extent of microleakage of Class 11 cavities restored with two different brands of resin-based composite, one hybrid (Tetric Ceram) and the other "packable" (Surefil) taking into account two variables: the localization of the margins and the insertion technique. Methods: 100 bovine teeth, recently extracted, had standardized Class II slot cavities prepared on the mesial and distal surfaces with the gingival floor located on enamel or dentin, for a total 200 cavities. The teeth were randomly divided into eight groups of 25 teeth each (25 restorations in each group): (1) margin on dentin, restored with Surefil, bulk insertion; (2) margin on dentin, restored with Tetric Ceram, bulk insertion; (3) Margin on enamel, restored with Surefil, incremental technique; (4) margin on enamel, restored with Tetric Ceram, incremental technique; (5) margin on enamel, restored with Surefil, bulk insertion; (6) margin on enamel, restored with Tetric Ceram, bulk insertion; (7) margin on dentin, restored with Surefil, incremental technique; (8) margin on dentin, restored with Tetric Ceram, incremental technique. After this procedure, the teeth were subjected to 1000 thermocycles, stained with 2% methylene blue solution, and then sectioned in the mesiodistal direction. Dye penetration at tooh/restoration interface was scored based upon the extent of the dye using a light stereoscope x 35. Results: All groups showed considerable levels of microleakage at both dentin and enamel margins (P< 0.05). Restorations with margins in enamel using the hybrid resin-based composite with the incremental technique did not show statistically significant differences when compared to bulk placement. However, restorations with hybrid resin-based composite have significantly less microleakage than either bulk or incremental technique for the "packable" resin-based composite Surefil. As for the margins in dentin, Tetric Ceram in bulk placement did not differ from the incremental technique and Tetric in bulk placement had significantly less microleakage than Surefil either bulk or incremental technique. The hybrid resin-based composite with margins in dentin and incremental technique showed less microleakage than the "packable" resin in bulk placement.1729910

Analysis of the interfacial micromorphology and bond strength of adhesive systems to Er:YAG laser-irradiated dentin

This study evaluated the effects of different parameters of dentin irradiation with erbium-doped yttrium aluminum garnet (Er:YAG) laser on bond strength to dentin and analyzed the ultramorphological characteristics of resin-laser-irradiated dentin interfaces using a transmission electron microscope (TEM). Dentin surfaces were abraded with SiC paper (600 grit) or Er:YAG laser-irradiated (120/4, 140/6, 180/4, or 200/6 mJ/Hz). Three adhesive systems were tested: Single Bond Plus (3M ESPE), Clearfil Protect Bond (Kuraray Med.), and Clearfil Tri-S Bond (Kuraray Med.). Treatments were performed over flat dentin surfaces of human third molars. Specimens were stored in distilled water for 1 week or 6 months and prepared for a microtensile bond strength test and interfacial ultrastructure for analysis. Microtensile bond strength data (n - 5) were analyzed with three-way analysis of variance. Irradiation with Er:YAG laser did not reduce the bond strength values for self-etching adhesives even after 6 months of water storage. The hybrid layer formation was observed only when the adhesives were applied to non-irradiated dentin (control group). Nanoleakage occurred in all resin-dentin interfaces using Single Bond Plus for both periods. Nanoleakage pattern and bond strength of self-etching adhesives to dentin were less affected by Er:YAG laser irradiation and by the 6-month storage in water than was those of the etch-and-rinse adhesive. TEM analysis revealed no hybridization when dentin was laser-irradiated. Clinical significance: Minimally invasive caries removal has been proposed. Nevertheless, bonding mechanisms to lased dentin are not entirely described. Knowing the interaction between the treated dentin and bonding agents and its behavior over time is of utmost importance for new technologies. Regarding that, two-bottle self-etching adhesive system provided a more consistent evidence of its better behavior when bonding to lased substrate.2841069107

Bond Strength of Adhesive Systems to Er, Cr:YSGG Laser-Irradiated Dentin

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Objective:The purpose of this study was to evaluate the effects of Er, Cr:YSGG laser irradiation and different adhesive procedures on bond strength of two bonding agents to dentin. Background data:Studies have shown that laser-irradiated dentinal tissue yields lower bond strengths than does nonirradiated dentin. In this study, different treatment methods of laser irradiating dentin were studied to enhance the bond strength of bonding agents to nonirradiated dentin. Methods:Third molars were wet ground with SiC until the occlusal flat dentin surface was exposed, and the teeth were randomly assigned to six groups (n = 5). A two-step self-etching primer (Clearfil SE Bond, G1) and a two-step etch-and-rinse adhesive (Single Bond Plus, G2) were applied to the nonirradiated dentin surface according to manufacturer's instructions, as control groups. In G3 and G4, the same adhesives were applied after Er, Cr:YSGG laser irradiation, whereas in G5 and G6 adhesives were applied after Er, Cr:YSGG laser irradiation, phosphoric acid etching, and NaOCl deproteinization of etched dentin. The Er,Cr: YSGG laser worked at 2.78 mu m and the repetition rate was fixed at 20 Hz. Composite blocks were built on bonded surfaces and the teeth were stored for 24 h at 37 degrees C. Restored teeth were vertically and serially sectioned to obtain bonded specimens for the bond strength test. Data were analyzed by two-way ANOVA and Tukey test (alpha = 5%). Results:Laser irradiation reduced bond strengths for the two adhesives, regardless of acid etching and deproteinization of dentin post-irradiation (p < 0.05). The self-etching primer system showed higher bond strengths to laser irradiated dentin than did Single Bond Plus (p < 0.05). The adhesive systems applied to normal dentin yielded higher bond strengths than when they were applied to laser irradiated dentin (p < 0.05). Conclusions:The self-etching primer seemed to be less affected by dentin irradiation with Er, Cr:YSGG laser. The additional etching and NaOCl solution did not overcome the effects of laser irradiation on dentin.o TEXTO COMPLETO DESTE ARTIGO, ESTARÁ DISPONÍVEL À PARTIR DE AGOSTO DE 2015.2911747752Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)CEPID-CEPOF [98/14270-8]Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)CAPES [05/56533-0]FAPESP [05/60697-9]CEPID-CEPOF [98/14270-8