Purpose:The aim of this study was to evaluate the tensile bond strength (TBS) of repairs in recent fillings of methacrylate- (MBC) or silorane-based composites (SBC) subsequent to different surface treatments.Materials and Methods:Fifty slabs of Filtek P60 (3M ESPE, St Paul, USA) and Filtek P90 (3M ESPE) were stored for 10 days in distilled water at 37°C. The surface of adhesion was abraded with a 600-grit silicone paper and repaired using each respective composite: G1, no treatment (control); G2, application of adhesive; G3, application of silane and adhesive; G4, sandblasting (Al2O3) and adhesive; and G5, sandblasting (Al2O3), silane, and adhesive. Further 10 slabs of each composite were also evaluated for cohesive strength (G6). After 30 days immersion in distilled water at 37°C, the TBS was determined.Results:TBS results were higher for MBC than for SBC (P = 0.00012). The experimental groups were similar for SBC and the TBS was 27% of its cohesive strength. For P60, sandblasting significantly improved the TBS compared to other groups. With MBC, G4 and G5, the TBS was approximately 47% of its cohesive strength.Conclusion:Sandblasting (Al2O3) improves the repair-strength of MBC, whilst for the SBC all treatments succeed. MBC presents higher repair strength than SBC.

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This article proposes a linear power assist unit for pedal-driven wheelchair and its control algorithm. The proposed power assist unit is controlled explicitly taking into consideration mechanical impedances of both a human operator and environment. In the proposed system, impedance variations for the environment are treated as a plant perturbation, but those of the human operator are considered to be identified to adapt the controller to the variations. For the first step, an identification method using Kalman filter is proposed, and evaluation results for a basic deterministic controller performance are reported. Simulation results showed that the proposed indemnification method is able to track impedance parameter varying about a frequency of 0.1 Hz. Experimental results showed that the prototype has robustly worked well against perturbations of the environment, keeping the power assist control bandwidth about 1 to 3 Hz.