Durability of composite repair using different surface treatments.

OBJECTIVE: To evaluate the surface treatment and hydrophilicity of the bonding agent on the composite repair strength (RS), silver nitrate uptake (SNU), surface roughness (SR) and estimation of surface area (SA). METHODS: Fifty resin blocks (Opallis, FGM) were polished and divided in 5 groups: no treatment (NT); roughening with a fine (FDB); medium (MDB); coarse-grit (CDB) and 50-µm aluminium oxide sandblasting (AO). A hydrophobic (Adhesive, Scotchbond Multi-Purpose Plus, 3M ESPE) or hydrophilic (Adper Single Bond 2, 3M ESPE) adhesive was applied, followed by composite placement (Opallis, FGM). Composite-composite bonded sticks (0.9 mm2) were tested in tension (1.0mm/min) immediately [IM] or after 6 months [6M] of water storage. Two sticks from each tooth, at each time, were immersed in a 50% silver nitrate solution and evaluated by SEM. A profilometer was used to measure SR. SEM images were used to estimate the SA using the Image J software. Data were analysed by ANOVA and Tukey's tests. RESULTS: The AO showed the highest CR strength for both adhesives, whilst the NT group showed the lowest, irrespective of the storage period. The diamond burs had intermediate performance. Silver nitrate deposits were seen after 6M for the hydrophilic adhesive. The ranking of SR values (Ra) from the lowest to the highest was: NT