Bond Strength of Resin Cements After Storage and Load Cycling

Objectives: This study evaluated the bond strength (BS) of dual-curing resin luting cements after artificial aging techniques (mechanical load cycling (MLC) and artificial saliva storage) to dentin. Methods: Occlusal dentin surfaces of 96 extracted human third molars were flattened to expose coronal dentin. Teeth were assigned to 12 groups (n=8) according to resin cement products and artificial aging techniques. The control groups were represented by immediate BS (24h after specimen preparation). Materials tested included conventional etch-and-rise and self-etching adhesives and their luting agents (RelyX ARC/Scotchbond Multi-Purpose and Clearfil Esthetic Cement/DC Bond, respectively), and two self-adhesive resin luting cements (RelyX Unicem and Clearfil SA Cement). All materials were used according to the manufacturers' instructions. Resin luting cements were applied to pre-polymerized resin discs (2 mm thick), which were subsequently bonded to the prepared dentin surfaces. Restored teeth were submitted to MLC (50.000 cycles at an axial force of 80N at a frequency of 1.0 Hz) or storage in artificial saliva for one year. Bonded beams were obtained from these restored teeth and tested in tension at a crosshead speed of 0.5 mm/min until failure. Data (in MPa) were analyzed by two-way ANOVA and Tukey test (á=0.05). Results: The BS of all cementing systems did not reduce after aging methods. Self-adhesive resin cements provided significantly higher BS than those conventional materials. The Clearfil Esthetic Cement showed the lowest BS to dentin. Conclusions: The MLC and the saliva storage for one year did not affect the BS to dentin of resin cements. Self-adhesive cements seem represent an option for luting procedures to dentin surfaces.

Acknowledgements: Support by FAPESP #09/51674-6 and 09/51281-4.