Influence of Methods of Application of Self-etching Adhesive Systems on Adhesive Bond Strength to Enamel

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Effects of Surface Hydration State and Application Method on the Bond Strength of Self-etching Adhesives to Cut Enamel

Purpose: To evaluate the effect of surface hydration state and application method on the microtensile bond strength of one-step self-etching adhesives systems to cut enamel.Materials and Methods: One hundred ninety-five bovine teeth were used. The enamel on the buccal side was flattened with 600-grit SiC paper. For the control group, 15 teeth received Adper Single Bond 2, applied according to manufacturer's recommendations. The other specimens were divided into three groups according to the adhesive system used: Futura Bond M (FM; Voco), Clearfil S-3 Bond (CS; Kuraray), and Optibond All in One (OA; Kerr). For each group, two hydration states were tested: D: blown dry with air; W: the excess of water was removed with absorbent paper. Two application methods were tested: P (passive): the adhesive was simply left on the surface; A (active): the adhesive was rubbed with an applicator point. A coat of Grandio composite resin (Voco) was applied on the surface. The teeth were sectioned to obtain enamel-resin sticks (1 x 1 mm), which underwent microtensile bond testing. The data in MPa were submitted to a three-way ANOVA and Tukey's test (alpha = 5%).Results: The ANOVA showed significant differences for application method and the type of adhesive, but not for hydration state. For the application method, the results of Tukey's test were: P: 31.46 (+/-7.09)a; A: 34.04 (+/-7.19)b. For the type of adhesive, the results were: OA: 31.29 (+/-7.05)a; CS: 32.28 (+/-7.14)a; FM: 34.68 (+/-7.17)b; different lower-case letters indicate statistically significant differences.Conclusion: Active application improved the bond strength to cut enamel. The adhesive Futurabond M showed the highest bond strength to cut enamel.

BOND STRENGTH DURABILITY of SELF-ETCHING ADHESIVES and RESIN CEMENTS TO DENTIN

Objectives: To evaluate the microtensile bond strength (mu TBS) of one-(Xeno III, Dentsply) and two-step (Tyrian-One Step Plus, Bisco) self-etching adhesive systems bonded to dentin and cemented to chemically cured (C&B Metabond) or light-cured paste of a dual-cure resin cement (Variolink II, Ivoclar) within a short (24 h) and long period of evaluation (90 days). Material and Methods: Forty recently extracted human molars had their roots removed and their occlusal dentin exposed and ground wet with 600-grit SiC paper. After application of one of the adhesives, the resin cement was applied to the bonded surface and a composite resin block was incrementally built up to a height of 5 mm (n = 10). The restored teeth were stored in distilled water at 37 C for 7 days. The teeth were then cut along two axes (x and y), producing beam-shaped specimens with 0.8 mm(2) cross-sectional area, which were subjected to mu TBS testing at a crosshead speed of 0.05 mm/min and stressed to failure after 24 h or 90 days of storage in water. The mu TBS data in MPa were subjected to three-way analysis of variance and Tukey's test (alpha = 0.05). Results: The interaction effect for all three factors was statistically significant (three-way ANOVA, p < 0.001). All eight experimental means (MPa) were compared by the Tukey's test (p < 0.05) and the following results were obtained: Tyrian-One Step Plus /C&B/24 h (22.4 +/- 7.3); Tyrian-One Step Plus /Variolink II/24 h (39.4 +/- 11.6); Xeno III/C&B/24 h (40.3 +/- 12.9); Xeno III/Variolink II/24 h (25.8 +/- 10.5); Tyrian-One Step Plus / C&B/90 d (22.1 +/- 12.8) Tyrian-One Step Plus/VariolinkII/90 d (24.2 +/- 14.2); Xeno III/C&B/90 d (27.0 +/- 13.5); Xeno III/Variolink II/90 d (33.0 +/- 8.9). Conclusions: Xeno III/Variolink II was the luting agent/adhesive combination that provided the most promising bond strength after 90 days of storage in water.

Some comments on the numerical simulation of self-synchronization of four non-ideal exciters

In this paper, self-synchronization of four non-ideal exciters is examined via numerical simulation. The mathematical model consists of four unbalanced direct Current motors with limited power supply mounted on a flexible Structural frame support. (c) 2004 Elsevier B.V. All rights reserved.

Temperature dependence and magnetocrystalline anisotropy studies of self-assembled L1(0)-Fe55Pt45 ferromagnetic nanocrystals

Temperature dependence and uniaxial magnetocrystalline anisotropy properties of the chemically synthesized 4 nm L1(0)-Fe55Pt45 nanoparticle assembly by a modified polyol route are reported. As-prepared nanoparticles are superparamagnetic presenting fcc structure, and annealing at 550 degrees C converts the assembly into ferromagnetic nanocrystals with large coercivity (H-C>1 T) in an L1(0) phase. Magnetic measurements showed an increasing in the ferromagnetically ordered fraction of the nanoparticles with the annealing temperature increases, and the remanence ratio, S=M-R/M-S congruent to 0.76, suggests an (111) textured film. A monotonic increase of the blocking temperature T-B, the uniaxial magnetocrystalline anisotropy constant K-U, and the coercivity H-C with increasing annealing temperature was observed. Magnetic parameters indicate an enhancement in the magnetic properties due to the improved Fe55Pt45 phase stabilizing, and the room-temperature stability parameter of 67, which indicates that the magnetization should be stable for more than ten years, makes this material suitable for ultrahigh-density magnetic recording application.(c) 2007 American Institute of Physics.

Incidence of self-reported hearing loss and associated risk factors among the elderly in São Paulo, Brazil: the SABE survey

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Fabrication and analysis of self-assembled photonic crystals structures

This paper presents the fabrication and analysis of a three-dimensional FCC photonic crystal (PhC) based on a self-assembly synthesis of monodispersive latex spheres. Experimental optical characterization, achieved by measurements of the specular reflectance under variable angles, indicated the clear presence of a Bragg diffraction pattern. Results are further explored by theoretical calculations based on the Finite Difference Time Domain (FDTD) method to determine the full PhC band structure.

Reproducibility and validity of self-perceived oral health conditions

The reproducibility and validity of self-perceived periodontal, dental, and temporomandibular joint (TMJ) conditions were investigated. A questionnaire was applied in interview to 200 adults aged from 35 to 44, who were attending as casual patients at Araraquara School of Dentistry, Sauo Paulo State University, Sauo Paulo, Brazil. Clinical examination was based on the guidelines of the World Health Organization manual. The interview and the clinical examination were performed in two occasions, by a calibrated examiner. Reproducibility and validity were, respectively, verified by kappa statistics (kappa) and sensitivity (Sen) and specificity (Spec) values, having clinical examination as the validation criterion. The results showed an almost perfect agreement for self-perceived TMJ (kappa=0.85) and periodontal conditions (kappa=0.81), and it was substantial for dental condition (kappa=0.69). Reproducibility according to clinical examination showed good results (kappa=0.73 for CPI index, kappa=0.96 for dental caries, and kappa=0.74 for TMJ conditions). Sensitivity and specificity values were higher for self-perceived dental (Sen=0.84, Spec=1.0) and TMJ conditions (Sen=1.0, Spec=0.8). With regard to periodontal condition, specificity was low (0.43), although sensitivity was very high (1.0). Self-perceived oral health was reliable for the examined conditions. Validity was good to detect dental conditions and TMJ disorders, and it was more sensitive than specific to detect the presence of periodontal disease.

One-year clinical performance of self-etch adhesives in posterior restorations

Purpose: To evaluate the 1-year clinical performance of three self-etching adhesives (Adper Prompt L-Pop, Clearfil S-3 Bond, iBond) in posterior composite restorations using one etch&rinse adhesive (One-Step Plus) as control. Methods: Upon approval by the Institutional Review Board, 121 restorations were inserted in 38 subjects. The adhesives were applied as per manufacturers' instructions. Preparations were restored with a nanofilled resin composite (Filtek Supreme) and evaluated at baseline, 6 months, and 1 year. Statistical analyses included the Chi-square distribution with the McNemar non-parametric test (P< 0.05). Results: At 1 year, 111 restorations in 35 subjects were evaluated using the USPHS modified criteria. No significant changes were observed for the etch&rinse adhesive One-Step Plus. At 1 year the number of Alfa ratings decreased significantly for Clearfil S-3 Bond and for iBond in the categories color match, marginal staining, and marginal adaptation. For Adper Prompt L-Pop, marginal adaptation at 1 year was significantly worse than at baseline. Postoperative sensitivity to air improved significantly for Adper Prompt L-Pop, Clearfil S-3 Bond, and iBond. When the evaluation criteria were paired at 1 year, iBond resulted in a significantly lower number of Alfa ratings than any of the other adhesives for color match, marginal staining, and marginal adaptation. One-Step Plus resulted in a greater number of Alfa ratings for marginal adaptation than either Adper Prompt L-Pop or Clearfil S-3 Bond. Marginal adaptation was significantly better for Clearfil S-3 Bond than for Adper Prompt L-Pop. The post-operative sensitivity measured at 1 year for Adper Prompt L-Pop was statistically better than that for One-Step Plus.

Postural control as a function of self- and object-motion perception

The goals of this study were to examine the visual information influence on body sway as a function of self- and object-motion perception and visual information quality. Participants that were aware (object-motion) and unaware (self-motion) of the movement of a moving room were asked to stand upright at five different distances from its frontal wall. The visual information effect on body sway decreased when participants were aware about the sensory manipulation. Moreover, while the visual influence on body sway decreased as the distance increased in the self-motion perception, no effects were observed in the object-motion mode. The overall results indicate that postural control system functioning can be altered by prior knowledge, and adaptation due to changes in sensory quality seem to occur in the self- but not in the object-motion perception mode. (C) 2004 Elsevier B.V.. All rights reserved.

The azomethine-H modified colorimetric method of boron determination at fertilizers.

The present work studied the azomethine-H colorimetric method for boron determination to fertilizers analysis applications. The reagent azomethine-H needs lights conditions of reaction that, jointed to the big sensibility and specificity, diffused its use in boron's dosage in many materials. The most suitable experimental parameters were established for such colorimetry, and analysis conditions: standard curve between 0,200 e 2,25 mg. L(-1) boron, in maximum absorption at 415nm, I cm cell and reading between 30 and 90 minutes standing after the final homogenization of the boron's solution in analyse and with dye reactive (azomethine If 0,90 % m/v solution at buffer ammonium acetate 1,82 mol . L(-1) - potassium acetate 0,10 mol . L(-1) - acetic acid 1,67 mol . L(-1)-EDTA 2,7 . 10(-2) mol . L(-1)-NTA 2,1.10(-2) mol . L(-1) pH 5,5). Statistics analysis of the results didn't present big differences when the same results were got by the colorimetric method offered and by the potentiometric, from AOAG, whatever in manufactured fertilizers or in lab sintetized fertilizers.

Mechanical behaviour of self-compacting concrete with hybrid fibre reinforcement

In this study, fibre-reinforced self-compacting concretes were developed for precast building components, incorporating either adherent metal fibres or polymeric synthetic slipping fibres or a combination of both. To achieve the warranted workability, compressive and splitting tensile strengths, compositions were determined by preliminary tests on self-compacting materials with various proportions of metal fibres. Bending tests in controlled deflection confirmed the positive contribution of fibres in the mechanical behaviour of self-compacting concrete. The comparison between vibrated and self-compacting concretes of similar mechanical characteristics indicated a possible better fibre-matrix bond in the case of self-compacting types. The results also showed that the properties of the hybrid fibre-reinforced self-compacting concrete could be inferred from the properties of the individual single-fibre reinforcements and their respective proportions through simple mix-rules.