Indirect Composite Bonded With Self-adhesive Cement

Objectives: This study evaluated the water storage effect on the efficacy of surface treatments, the fracture pattern and the interface morphology between the self-adhesive cement (Unicem, 3M ESPE) and indirect composite with scanning electron microscopy (SEM). Methods: Cylindrical blocks of indirect composite (MZ100, 3M ESPE) were cemented in pairs using self-adhesive resin cement according to the following surface treatment methods (n=25): G1- control; G2- Al2O3 mechanical treatment; G3- metal primer (Alloy Primer, Kuraray); G4- Al2O3 mechanical treatment and metal primer; G5- silane (Ceramic Primer, 3M Espe); G6- Al2O3 mechanical treatment and silane. The pairs were sectioned 24 hours latter, producing beams with cross-section area of 0.8mm2. Microtensile test was performed 48 hours, 40 days and 6 months after cementation using a universal testing machine at 0.5mm/min. The data were analyzed using 2-way ANOVA and Tukey test (á=.05). All fractured specimens were examined in scanning electron microscopy (SEM) and classified by fracture pattern. Four discs were designed to SEM interface analysis: (1) control; (2) Al2O3 mechanical treatment. Results: The results found for 48 hours, 40 days and 6 months water storage were respectively: G1, 45.68, 48.07, 37.03; G2, 47.18, 45.56, 37.77; G3, 36.17, 37.84, 30.91; G4, 41.68, 34.17, 29.10; G5, 42.22, 41.8, 36.22; G6, 45.89, 45.59, 36.78. After 6 month the metal conditioner groups presented the lowest bond strength. A great number of cohesive fracture and mixed patterns were observed in all experimental groups except G1 group with much more adhesive failures. SEM images showed a direct contact between indirect composite and the resin cement without the presence of voids or defects. Conclusion: The self-adhesive cement can be used directly on indirect composite without surface treatment. Although, silane could be used as a chemical treatment associated with mechanical treatment for more interaction among self-adhesive cement and indirect resin composite.