Reparability of aged silorane with metahcrylate-based resin composite: micro-shear bond strength and scanning electron microscopy evaluation

Objectives: To evaluate the compatibility between aged siloranes and methacrylate-based composites by simulating a common repair-technique. Methods: Twenty substrates were constructed using silorane (Filtek Silorane, 3M ESPE) and methacrylate composites (Filtek Supreme XT, 3M ESPE). Substrates were aged in 0.9% NaCl solution at 37 degrees C for 72 hours. Silorane build-ups were constructed on silorane substrates without any intermediate layer (IL). Methacrylate build-ups were constructed on silorane substrates without any IL, with a methacrylate IL (Heliobond, Ivoclar Vivadent), or with a phosphate-methacrylate IL (Silorane System Adhesive Bond, 3M ESPE). Methacrylate build-ups were also constructed on methacrylate substrates without any IL. The micro-shear bond strength test was carried out after thermocycling. Bond strength data were statistically analyzed using analysis of variance and Tukey post hoc tests. Failure modes were assessed by means of scanning electron microscopy observations. Results: The silorane-methacrylate group without any IL showed the lowest bond strength values (0.4 +/- 0.1 MPa). The use of a methacrylate-based IL (1.6 +/- 1.7 MPa) led to a slight increase in bond strength, whereas the use of phosphate-methacrylate IL (9.1 +/- 5.4 MPa) significantly increased bond strength. There was no statistically significant difference in bond strength between silorane-silorane (7.9 +/- 3.6 MPa) and methacrylate-methacrylate (9.5 +/- 4.1 MPa) groups without any IL.