Shear bond strength of metal-ceramic repair systems

This study evaluated the shear bond strength of different repair systems to nickel-chromium (NiCr) alloy after storage in water for either 24 hours or six months. One hundred cylindrical specimens (3 mm thick x 9 mm diameter) were fabricated using an NiCr alloy and embedded in a PVC ring, where they received one of five bonding and resin composite repair treatments (n = 20): Clearfil SE Bond/Clearfil AP-X (Group 1), Bistite II DC/Palfique (Group 2), CoJet/Z100 (Group 3), Scotchbond Multi-Purpose Plus/Z100 (Group 4; reference group), and CoJet Sand plus Scotchbond Multi-Purpose Plus/Z100 (Group 5). The specimens were stored in distilled water for 24 hours at 37 degrees C, thermocycled for 1,000 cycles in two baths (at 5 degrees C and 55 degrees C) with a dwell time of 30 seconds for each bath, and stored in distilled water at 37 degrees C for either 24 hours or six months. At 24 hours, Group 3 presented the highest mean values (P < 0.001); at six months, Group 5 demonstrated the highest mean values (P < 0.001). At six months, Group 5 presented a significant increase in shear bond strength (P < 0.001), while Groups 1 and 3 showed a significant reduction (P < 0.001). There were no significant differences between the storage times for Group 2 (P = 0.064) or Group 4 (P = 0.490).