Influence of surface treatments on the bond strength of repaired resin composite restorative materials

ObjectivesThe purpose of this study was to investigate the effect of different surface treatments on the bond strength (σ) of repaired, aged resin composites (ARC).MethodsForty blocks of Filtek Z250™ (Z2) and Filtek Supreme™ (SU) were made, stored in deionized water for 9 days, and randomly assigned to different surface treatment groups: hydrofluoric acid etching (HA), abrasion using a coarse diamond bur (AB), sandblasting with alumina particles (AO), and silica coating (SC). The average roughness (Ra) of the treated surfaces was measured with a profilometer. An adhesive system (SB-Adper Single Bond Plus™), a silane (SI) or a combination of both (SI + SB) were applied after each surface treatment. The blocks were restored with the same composite (RC) and cut to produce bars that were turned into dumbbell-shaped specimens (0.5 mm2) using a precision grinding machine. The specimens (n = 30) were tested in tension to fracture and the microtensile bond strength (σ) values were calculated (MPa). Data were analyzed using three-way ANOVA/Tukey test (α = 0.05) and Weibull statistics.ResultsAO and SC produced similar Ra values, which were greater than the value produced by HA. The σ values were statistically influenced by the type of RC (p < 0.0001), by the surface treatment (p < 0.0001) and by the surface coating (p < 0.0001). Treating the surface of Z2 with SC + SB produced the greatest m value.SignificanceAO and SC produced the greatest σ values, irrespective of the primer (SI, SB or SI + SB) used. Yet, the RC microstructure influenced the mean σ values, which were greater for Z2 than for SU. The HA should not be used for repairing ARC.