Avaliação da resistência à tração entre sistemas para reparo de revestimento estético e liga de níquel-cromo.

Resumo

Objectives: This study evaluated the adhesive bond strength between four repair systems and a nickel-chromium alloy for metalceramic crowns. Material and Methods: Twenty-four blocks of nickel-chromium with dimensions of 5x5x5 mm were cast and divided into four groups of six blocks. Each group was conditioned with the following surface treatments: G1- sandblasting with Al₂O₃ (50 µm) + Alloy Primer (Kuraray); G2-sandblasting with Al₂O₃ (50 µm) + 37% phosphoric acid + Adper Single Bond 2 (3M); G3- Cojet-Sand System (3M); G4- Cojet-Sand System (3M) + Adper Single Bond 2 (3M). On the conditioned face of the metal blocks was applied composite resin until obtaining a symmetrical resin block. These sets were split up, obtained 96 samples of 10x1x1 mm, with adhesive surface of 1 mm². After thermocycling (500 cycles at 5-55 °C) all samples were submitted to the microtensile test in an universal test machine (EMIC) with crosshead speed of 1mm/min. Results: Means and standard deviation of bond strength (MPa) were: G1: 24.49 ± 4.80, G2: 19.51 ± 3.90, G3: 38.93 ± 3.37 and G4: 36.49 ± 3.45. The data were analyzed by the analysis of variance test (ANOVA) indicating that values of bond strength of the group G3 and G4 were significantly larger than the groups G1 and G2. Conclusion: It was concluded that the NiCr alloy conditioned with Cojet-Sand (G3 and G4) increased the values of bond strength to composite resin compared to the surface treatments of groups G1 and G2.