Surface roughness of etched composite resin in light of composite repair

Objectives rch for clinically effective composite repair protocols, the effect of various etching protocols on the surface roughness of composite resins with different filler composition were investigated. s composite resins (hybrid-filled Clearfil AP-X; nano-filled Filtek Supreme XT) specimens of 3 mm thick with a diameter of 7 mm were prepared (n = 24). The top surface was polished with 4000-grit SiC-abrasive paper and subjected to one of eight surface treatments: (n = 3): negative control (NC), 37% phosphoric acid for 20 s (37PA-20 s), 3% hydrofluoric acid for 20 s (3HF-20 s), for 120 s (3HF-120 s), 9.6% hydrofluoric acid for 20 s (9.6HF-20 s), for 120 s (9.6%HF-120 s), 37PA-20 s followed by 9.6%HF for 120 s (37PA-20 s/9.6HF-120 s) and 9.6%HF for 120 s followed by 37PA-20 s (9.6HF-120 s/37PA-20 s). Roughness (Sa) was measured using a 3D noncontact optical interferometer (WYKO) and surface topography imaged by SEM. Multilevel models were used to estimate the variances within a sample and between samples in each group. Using the resulting overall variances and the means for each group, the eight groups were compared consecutively using t-tests (p < 0.05). s brid-filled composite resin demonstrated a significantly rougher surface than the nano-filled (p < 0.05). For both composites 9.6%HF-120 s, 37PA-20 s/9.6HF-120 s and 9.6%HF-120 s/37PA-20 s resulted in a large increase in roughness compared to the other groups (p < 0.05). For the hybrid-filled, the succeeding groups (37PA-20 s, 3HF-20 s, 3HF-120 s and 9.6HF-20 s) resulted in a statistically significant increase in surface roughness (p < 0.02). For the nano-filled only a statistically significant increase in roughness was found between 3HF-20 s and 3HF-120 s (p < 0.001) and between 9.6HF-20 s and 9.6HF-120 s (p < 0.001). SEM surface characterization revealed that the hybrid-filled composite resin was much more affected by etching than the nano-filled. icance ite resins should not be seen as a group of materials having identical properties when it comes to repair. The effect of etching will depend on the composition of the filler particles.