Bond Strength Between Repair Systems and Nickel-Chromium Alloy

Objective:  This study evaluated the adhesive bond strength between four repair systems and a nickel-chromium alloy (Wiron 99 – Bego).Method: Twenty-four blocks of nickel-chromium with dimensions of 5x5x5mm were cast and divided into four groups of six blocks (G1, G2, G3 and G4). 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- sandblasting with SiO₂ (30 µm) Cojet-Sand (3M) + silane ESPE-Sil (3M); G4- sandblasting with SiO₂ (30 µm) Cojet-Sand (3M) + silane ESPE-Sil (3M) + Adper Single Bond 2. On the conditioned face of the metal blocks was applied composite resin Z-350 (3M) until obtaining a symmetrical resin block.Thus were formed twenty four sets of metal blocks bonded to composite resin blocks. These sets were split up, obtained 96 samples of 10x1x1mm, with adhesive surface of 1mm². All samples were subjected to 500 thermal cycles in water between 5 and 55 ºC, for 30 seconds each bath. After this, the samples were submitted to the microtensile test in an universal test machine (EMIC) with crosshead speed of 1mm/min. Result: 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) and Tukey test, p<0.05 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 compared to the surface treatments of groups G1 and G2.