To evaluate the effect of different surface treatments on a nanofilled resin composite, using scanning electron microscopy (SEM).
Method:
15 resin-composite discs were made of Filtek XT (3M ESPE, St Paul, Minnesota, EUA). The specimens were obtained using a round silicone mold (10mmx2mm) and all were finished and polished with a three-grit polishing disc system (OptiDisc, Kerr Hawe, Bioggo, Switzerland). After 24 hours stored in distilled water at 37º C, the specimens were randomly assigned to five groups (N=15): Group 1- control group, Group 2- phosphoric acid 35% for 15sec, Group 3- diamond bur for 15sec, Group 4- aluminum oxide (50 μm) sandblast for 15sec, Group 5- sodium bicarbonate sandblast for 15sec. Samples were prepared to be observed by SEM and photographs were taken at different magnifications (33x, 150x, 250x, 500x and 1000x) for each specimen (Hitachi S-450®).
Result:
All surface treatments resulted on morphological differences among the specimens. Major irregularities and micro and macro retentions were observed on the group were specimens sandblasted with aluminum oxide, followed by the diamond bur group, the sodium bicarbonate sandblast group and the phosphoric acid group, where the surface was less affected.
Conclusion:
The application of phosphoric acid or sodium bicarbonate sandblast as surface treatment for composite repair did not create an irregular surface on the resin as other surface treatment methods tested, which may be insufficient to obtain good adhesion.