The effect of moisture on the shear bond strength of gold alloy rods bonded to enamel with a self-adhesive and a hydrophobic resin cement

The aim of this in vitro study was to investigate the influence of enamel moisture on the shear bond strength (SBS) of a hydrophobic resin cement, Maximum Cure® (MC), and a self-adhesive resin cement, Multilink Sprint® (MLS), after etching of the enamel. Forty cylindrical gold alloy rods were used to simulate the Incognito® lingual bracket system. They were bonded to the enamel of 40 human teeth embedded in self-cured acrylic resin. Twenty were bonded with MC (10 on dry and 10 on wet enamel) and 20 with MLS (10 on dry and 10 on wet enamel). The SBS of MC and MLS was determined in a universal testing machine and the site of bond failure was defined by the adhesive remnant index (ARI). A Kruskal–Wallis test was performed followed by Games–Howell post hoc pairwise comparison tests on the SBS results ( P < 0.05) and a chi-square test was used for the analysis of ARI scores ( P < 0.05). On dry enamel, no significant differences between MC (58 ± 5 MPa) and MLS (64 ± 13 MPa) were noted. On wet enamel, the adherence of MC (6 ± 8 MPa) and MLS (37 ± 13 MPa) significantly decreased but to a lesser extent for MLS. The ARI scores corroborated these results. In conclusion, MC did not tolerate moisture. MLS was also affected but maintained sufficient adherence.