72 - Six-Year Bond Stability of Universal Adhesives with Alternative Dentin Treatments

Abstract

Evaluate the effects of four dentin treatments on microtensile bond strength (MBS) for two universal adhesives, ScotchBond Universal (SBU) and All-Bond Universal (ABU), after 24-hour, 1-year and 6-year water storage. Flat dentin surfaces from human molars were treated as follows: (i) phosphoric acid 35% (PA) for 15 s; (ii) PA for 5 s; (iii) 17% EDTA for 60 s; (iv) no treatment (self-etch mode). One of the two universal adhesives was then applied to the surface. After 24-hour storage at 37 C, teeth were sectioned to obtain beams (~0.9mm2) and randomly assigned to one of the storage times (24 h, 1-y and 6-y). Specimens were tested until failure at 1.0 mm/min on each incubation period. Failure modes were assessed with light microscope at 40x (Olympus, Tokyo, Japan). Data was submitted to Three-Way ANOVA and all pairwise multiple comparison (Holm-Sidak) at significance level = 0.05. Statistical differences were detected for surface treatments and storage times. A significant interaction between adhesive and treatment was found (p<0.01). The bond strengths were affected by the different surface treatments, depending on the adhesive, except for 17% EDTA with similar results for both systems. After 6-year storage, SBU showed more stable MTBS with 17% EDTA 32.36 (14.09) and self-etch mode 30.10 (13.80) (p<0.05). For ABU, the lowest MTBS was observed with the self-etch mode for all storage times (p<0.01). However, 17% EDTA treatment for ABU at 6-year storage 39.85 (21.03) exhibited the highest MTBS (p<0.01). Overall, 17% EDTA treatment showed a positive effect on dentin bonding stability. The self-etch mode showed better performance for SBU compared to ABU. The failure modes for all groups were predominantly adhesive and mixed. The dentin bonding stability with universal adhesives depends on the surface treatment for each adhesive material. The use of 17% EDTA for 60 s to treat dentin prior to the application of universal adhesives could be considered an alternative approach to improve bond durability.