Shear bond strengths of two commercially available dentine-amalgam bonding systems

Objectives: The purpose of this in vitro study was to determine the shear bond strengths (SBS) of amalgam to dentine treated with the Amalgambond Plus System (AM) and All-bond 2 System (AL) after storage periods in physiological saline for up to 48 weeks. Methods: The occlusal superficial dentine surfaces of 150 extracted human molars were exposed by wet grinding on 600-grit silicon carbide and the bonding area demarcated with a perforated adhesive tape. Freshly mixed Tytin amalgam was transferred to the opening in a split Teflon mold on the demarcated dentine surfaces treated with either AM or AL as directed by the manufacturers. The SBS of AM after 24 h (A), 4 weeks (B), 12 weeks (C), 24 weeks (D), and 48 weeks (E), and of AL after 24 h (F), 4 weeks (G), 12 weeks (H), 24 weeks (I), and 48 weeks (J), were determined with a knife-edged rod at a crosshead speed of 0.5 mm/min and expressed in megapascal (MPa). The data were analyzed by ANOVA and Studentʹs t-test. Results: The mean ±SD of SBS in MPa were: A: 14.6 ± 4.0; B: 14.5 ± 3.6; C: 15.3 ± 4.8; D: 14.6 ± 4.6; E: 13.9 ± 4.0; F: 9.5 + 4.7; G: 12.1 ± 1.7; H: 10.2 ± 3.5; I: 12.0 ± 3.9; J: 11.9 ± 3.5. The SBS of the five groups treated with AM (A, B, C, D and E) were not significantly different (P > 0.05) and the SBS of the five groups treated with AL (F, G, H, I and J) were not significantly different (P > 0.05). The SBS of A vs. F, B vs. G, ad C vs. H, were significantly different (P < 0.05), but D vs. I and E vs. J were not significantly different (P > 0.05). Conclusion: The SBS of amalgam to dentine treated with AM and AL were not adversely affected by the duration of storage.