Tensile bond strength of composite repairs on Artglass using different surface treatments

To determine the tensile bond strength of composite repairs applied to Artglass using different surface treatments.

Blocks of Artglass were embedded in PVC cylinders with self-cure acrylic resin and divided into 18 groups according to the surface treatment. Three mechanical treatments and six chemical treatments were combined. Mechanical treatments were: sandpaper, diamond bur and microetch. Chemical treatments were: Prime & Bond 2.1 (PB) only, phosphoric acid+PB, hydrofluoric acid (applied for 1 or 3 minutes) +PB, Artglass Liquid only and silane+PB. After surface treatment, a composite truncated cone (Charisma, shade A3) was built. Tensile test was carried out after 24 hrs storage in distilled water at 37 degrees C. Failure mode was assessed using a x 10 stereomicroscope. Artglass surfaces treated mechanically and their combination with phosphoric acid and hydrofluoric acid were analyzed by scanning electron microscopy (SEM).

Two-way ANOVA revealed that there was no statistical difference in bond strength among the three mechanical treatments used, except for the groups where Artglass Liquid and silane were used. The use of phosphoric acid and Artglass Liquid did not improve the bond strength of the specimens compared to the groups where only PB was applied, regardless of the mechanical treatment. Hydrofluoric acid treatment for 1 and 3 minutes reduced the bond strength significantly compared to the other chemical treatments. The association of silane with microetching resulted in a statistically higher bond strength compared to all the other experimental groups. SEM analysis showed that the application of phosphoric acid failed to promote changes in mechanically treated samples. On the other hand, when hydrofluoric acid was associated to either diamond bur or microetching, the topography created by the mechanical treatment was at least partially destroyed.