Marcelo Tavares de Oliveira

Effect of surface treatments of laboratory-fabricated composites on the microtensile bond strength to a luting resin cement

The purpose of this study was to evaluate the influence of different surface treatments on composite resin on the microtensile bond strength to a luting resin cement. Two laboratory composites for indirect restorations, Solidex and Targis, and a conventional composite, Filtek Z250, were tested. Forty-eight composite resin blocks (5.0 x 5.0 x 5.0mm) were incrementally manufactured, which were randomly divided into six groups, according to the surface treatments: 1- control, 600-grit SiC paper (C); 2- silane priming (SI); 3- sandblasting with 50 mm Al2O3 for 10s (SA); 4- etching with 10% hydrofluoric acid for 60 s (HF); 5- HF + SI; 6 - SA + SI. Composite blocks submitted to similar surface treatments were bonded together with the resin adhesive Single Bond and Rely X luting composite. A 500-g load was applied for 5 minutes and the samples were light-cured for 40s. The bonded blocks were serially sectioned into 3 slabs with 0.9mm of thickness perpendicularly to the bonded interface (n = 12). Slabs were trimmed to a dumbbell shape and tested in tension at 0.5mm/min. For all composites tested, the application of a silane primer after sandblasting provided the highest bond strength means.

SEM analysis of the acid-etched enamel patterns promoted by acidic monomers and phosphoric acids

Objective: Although self-etching bonding systems (SES) are indicated to prepare dental enamel for bonding, concerns have been expressed regarding their effectiveness. The aim of this study was to analyze the etching pattern (EP) of nine SES in comparison with 35% and 34% phosphoric acid etchants (FA) on intact (IN) and ground (GR) enamel surface. Materials and Methods: Twenty-two human third molars were sectioned in mesial-distal and buccal-lingual directions, and four dental fragments were obtained from each tooth. Half of the fragments were ground using 600-grit SiC paper and the other half remained intact. The fragments were randomly assigned into 22 groups, according to the texture of enamel surface (IN and GR) and the technique to etch the enamel (34% FA, 35% FA, AdheSE primer; Brush & Bond; Clearfil Protect Bond primer; iBond; One-up Bond F; OptiBond Solo Plus primer; Tyrian SPE primer; Unifil Bond primer and Xeno III). Conditioners were applied to IN and GR enamel surfaces, according to the manufacturers instructions. Specimens etched with phosphoric acids were washed with water, while the surfaces treated with SES were submitted to alternate rinsing with alcohol and acetone. The specimens were dried, sputter-coated and examined under a scanning electron microscope. Results: For both IN and GR enamel surfaces, the EP of 34 and 35% FA was deeper and more homogeneous in comparison to EP of SES, except for Tyrian SPE. The acidic monomer action of self-etching systems was more effective on GR enamel. Conclusion: Most of the SES are less aggressive than phosphoric acid etchants and their etching effects were reduced on intact enamel surfaces. Uniterms: Dental acid etching; Dental enamel; Electron microscopy.

Micromorphology of Resin-Dentin Interfaces Using One-Bottle Etch&Rinse and Self-Etching Adhesive Systems on Laser-Treated Dentin Surfaces: A Confocal Laser Scanning Microscope Analysis

This study evaluated the hybrid layer (HL) morphology created by three adhesive systems (AS) on dentin surfaces treated with Er:YAG laser using two irradiation parameters.

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

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 manufacturers 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??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?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 (?=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.

Silorane- and high filled-based"low-shrinkage" resin composites: shrinkage, flexural strength and modulus

This study compared the volumetric shrinkage (VS), flexural strength (FS) and flexural modulus (FM) properties of the low-shrinkage resin composite Aelite LS (Bisco) to those of Filtek LS (3M ESPE) and two regular dimethacrylate-based resin composites, the microfilled Heliomolar (Ivoclar Vivadent) and the microhybrid Aelite Universal (Bisco). The composites (n = 5) were placed on the Teflon pedestal of a video-imaging device, and VS was recorded every minute for 5 min after 40 s of light exposure. For the FS and FM tests, resin discs (0.6 mm in thickness and 6.0 mm in diameter) were obtained (n = 12) and submitted to a piston-ring biaxial test in a universal testing machine. VS, FS, and FM data were submitted to two-way repeated measures and one-way ANOVA, respectively, followed by Tukeys post-hoc test (a = 5%). Filtek LS showed lower VS than did Aelite LS, which in turn showed lower shrinkage than did the other composites. Aelite Universal and Filtek LS exhibited higher FS than did Heliomolar and Aelite LS, both of which exhibited the highest FM. No significant difference in FM was noted between Filtek LS and Aelite Universal, while Heliomolar exhibited the lowest values. Aelite LS was not as effective as Filtek LS regarding shrinkage, although both low-shrinkage composites showed lower VS than did the other composites. Only Filtek LS exhibited FS and FM comparable to those of the regular microhybrid dimethacrylate-based resin composite.

Bond strength of resin cements to Co-Cr and Ni-Cr metal alloys using adhesive primers.

PURPOSE The aim of this study was to evaluate the effectiveness of adhesive primers (APs) applied to Co-Cr and Ni-Cr metal alloys on the bond strength of resin cements to alloys. MATERIALS AND METHODS Eight cementing systems were evaluated, consisting of four resin cements (Bistite II DC, LinkMax, Panavia F 2.0, RelyX Unicem) with or without their respective APs (Metaltite, Metal Primer II, Alloy Primer, Ceramic Primer). The two types of dental alloys (Co-Cr, Ni-Cr) were cast in plate specimens (10 x 5 x 1 mm(3)) from resin patterns. After casting, the plates were sandblasted with aluminum oxide (100 microm) and randomly divided into eight groups (n = 6). Each surface to be bonded was treated with one of eight cementing systems. Three resin cement cylinders (0.5 mm high, 0.75 mm diameter) were built on each bonded metal alloy surface, using a Tygon tubing mold. After water storage for 24 hours, specimens were subjected to micro-shear testing. Data were statistically analyzed by two-way ANOVA and Tukeys studentized range test. RESULTS The application of Metal Primer II resulted in a significantly higher bond strength for LinkMax resin cement when applied in both metal alloys. In general, the cementing systems had higher bond strengths in Co-Cr alloy than in Ni-Cr. CONCLUSIONS The use of AP between alloy metal surfaces and resin cements did not increase the bond strength for most cementing systems evaluated.

Adhesive bonding of resin cements to cast titanium with adhesive primers

The purpose of this study was to evaluate the effects of adhesive primer applications on the bond strength of resin cements to cast titanium. Four adhesive primers - Metaltite, Metal Primer II, Alloy Primer and Ceramic Primer - and their respective resin cements - Bistite II DC, Link Max, Panavia F 2.0, RelyX Unicem and RelyX ARC - were tested. Cast plates were prepared from titanium ingots (n=6 specimens/cement) and had their surfaces airborne-particle abraded with Al2O3 (50 μ m). Three resin cement cylinders were built on each bonded titanium surface, using a cylindrical translucent tubing mold and were subjected to micro-shear testing. Data were analyzed statistically by two-way ANOVA and Tukeys post-hoc test (α=0.05). The application of Metal Primer II and Ceramic Primer resulted in significant higher bond strength for Link Max and RelyX Unicem resin cements, respectively, than nonuse of adhesive primers. Panavia F 2.0 and RelyX ARC yielded high bond strength means with or without adhesive primers. The use of adhesive primers might increase the bond strength to cast titanium depending on the resin cement used.

Enamel and dentin bond strength, interfacial ultramorphology and fluoride ion release of self-etching adhesives during a pH-cycling regime.

PURPOSE This study evaluated the effects of pH cycling on fluoride release and bond strength of two self-etching adhesive systems to both enamel and dentin. The ultramorphology of the interfaces produced by the adhesive systems were also analyzed. MATERIALS AND METHODS The buccal surfaces of bovine incisors were flattened to expose enamel and dentin, which were bonded with either Clearfil Protect Bond (CPB) or One-Up Bond F Plus (OBP). The bonded samples were prepared for microtensile bond strength (μTBS) testing, fluoride ion release, and transmission electron microscopy. pH cycling comprised demineralization (8 h/day) and remineralization (16 h/day) cycles for 8 days. The μTBS data were analyzed by two-way ANOVA, while fluoride release was analyzed using the Friedman and Wilcoxon tests. RESULTS The adhesives presented similar bond strengths to enamel. However, the dentin bond strength of CPB was higher than that of OBP. pH cycling did not influence enamel or dentin μTBS. The amount of fluoride released from the bonded enamel and dentin was low and varied among the groups. The morphological evaluation showed that the thickness of the dentin hybrid layers was similar for both adhesives. CONCLUSION The pH-cycling regime did not affect enamel or dentin bond strengths. In enamel, both the self-etching adhesives tested presented similar bond strengths, but in dentin, Clearfil Protect Bond showed higher dentin bonding than One-Up Bond F Plus.