Repair of silorane-based dental composites: Influence of surface treatments

Objective. The purpose of our study was to evaluate the effects of surface treatment on the microtensile bond strength (MTBS) of repaired silorane-based composites (Filtek Silorane (Silorane), 3M ESPE). Methods. The surfaces of the aged Silorane blocks (6 mm x 6 mm x 5 mm) were ground with 320-grit SiC paper. The subsequent surface treatments were: no treatment, bonding agent, acetone, acetone + bonding agent, ethanol, ethanol + bonding agent, silane and silane + bonding agent. Another group made from Silorane without repair served as positive control. New Silorane was bonded onto the treated samples. The MTBS test was performed (1 mm/min) with beam-shaped sticks (1.0 mm x 1.0 mm x 10 mm) before and after fatigue simulation (FS). The Weibull moduli for the MTBS data were also calculated. The fracture modes were examined with an optical microscope. The aged specimens after grinding were observed in a SEM and the percentage of uncovered filler surface in relation to the whole surface was calculated. Results. There were no significant differences between the no treatment group and the acetone only or ethanol only groups. Bonding agent improved the MTBS and the Weibull modulus. Although the SEM image revealed only 5.1% of uncovered filler surface, silane improved the MTBS. The groups with silane and bonding agent had the highest strength values except two groups and showed a fairly large number of cohesive failures. However, after FS, the differences between almost all groups were insignificant. FS increased the MTBS of almost all groups. Significance. The application of silane and bonding agent enhanced the initial repair strength. (C) 2012 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.