Repair of bulk-fill composite after different surface treatments

Abstract

Purpose To evaluate the effect of different surface treatments on the shear bond strength of repaired aged bulk-fill composites. Materials and method 60 cylindrical specimens of bulk-fill composite (X-tra fil) were prepared and stored in artificial saliva for 3 months. They were divided randomly into 2 groups according to the different repair material (n = 30), (I) X-tra fil and (II) Grandio. Then, they were further divided into 3 subgroups according to surface treatments (n = 10), (A) no surface treatment (B) diamond bur abrasion, and (C) air abrasion. Futurabond U adhesive was applied to all specimens, and then the repair composites were added. All specimens were subjected to thermo-cycling. They were tested for shear bond strength using a universal testing machine. Fractured samples were examined under a stereomicroscope to determine the mode of failure. An additional 30 specimens were made to evaluate the surface roughness. Representative SEM micrographs for each surface treatment were taken to assess the surface topography. All data was collected, tabulated and statistically analyzed. Results Group I: The highest mean shear bond strength was recorded in the group (IB) followed by (IC) and then (IA). Group (IA) was significantly different from groups (IB) and (IC) (P < 0.05). Group II: The highest mean shear bond strength was recorded in the group (IIB) followed by (IIC) then (IIA). Group (IIB) was significantly different from group (IIA) (P < 0.05). All surface treatments demonstrated significantly greater shear bond strength than not having any physical surface treatment. Repairing X-tra fil can be performed by either X-tra fil or Grandio with no statistically significant difference. Most of the specimens in all groups showed mixed and cohesive failures. Diamond bur abrasion showed the highest surface roughness values followed by air abrasion then control group. Conclusion The shear bond strength of repaired bulk-fill composite with bur or air abrasion was comparable and greater than no surface treatment. There was no significant difference between the two repair materials used.