Effect of surface treatments on the spreading velocity of simplified adhesive systems.

Objectives: To determine the roughness of glass surfaces submitted to different treatments and to correlate it with the spreading velocity of two adhesive systems.

Materials And Methods: Glass slides were used as substrates to evaluate the spreading velocity of Single Bond and Prime & Bond NT adhesive systems. Six different surface treatments were compared: 1) no treatment; 2) silanization (SL); 3) sandblasting (SB); 4) SB + SL; 5) 10% hydrofluoric acid treatment (HF); 6) HF + SL. Before and after treatments, surface roughness was measured by a profilometer (Ra, microm). Drop volumes (10 microl) of the adhesive systems were deposited onto substrates with a micropipette to observe materials spreading during 30s. Data were expressed in mm/s as spreading velocity. Statistical significances among groups were analyzed using one-way and two-way-ANOVA designs and the SNK test.

Results: Significant differences in spreading velocity were found between materials (p < 0.001) and among treatments (p < 0.001). Silanization decreased the spreading velocity for both adhesives in comparison to groups where it was not performed (p < 0.05). Differences in roughness were found only for SB surfaces that were rougher than the others (p < 0.05). Silanization decreased the roughness of SB surfaces (p < 0.05). Linear regression did not indicate any correlation between spreading velocity and roughness (R = 0.173).

Conclusion: Although surface treatments yielded different roughness, they did not provide differences in the spreading velocity of the simplified bonding systems studied. Silanization decreased bonding systems' spreading velocities.