Objectives : Repeated exposure to cyclic temperatures can result in change of bond strength. The purpose of this study is to determine the difference in shear bond strengths between a standard 24-h test and a 4000×-thermo-cycle (TC) test for a range of resin cements and bonding substrates using a newly developed shear bond strength testing rig assembly.
Materials and methods : Rexillium III (Pentron) and Vitabloc ® (Vita Zahnfabrik) samples were sand blasted using 50-μm alumina, then washed with ethanol and dried. Cement was mixed in accordance with manufacturers’ instructions and applied to one end of a 4 mm diameter × 5 mm long acrylic rod. The rod was inserted into a thin walled stainless steel tube with 3.5 mm ID held onto the substrate by a self-aligning rig. A 400 g load was placed on the rod for 15 s after which samples were placed in an incubator (37 °C, 100% relative humidity). After 1 h the samples were removed from the rigs and stored in water (37 °C) for 24 h. Shear bond strengths were taken by forcing the bonded mold assembly off the substrate. The thermo-cycled test followed the same methodology as the 24-h test except for an additional step whereby each sample was cycled between 5 and 55 °C water baths for 4000 cycles.
| seT PP | G-cem automix | Maxcem Elite | RelyX Clicker | |||||
|---|---|---|---|---|---|---|---|---|
| 24 h | TC | 24 h | TC | 24 h | TC | 24 h | TC | |
| Rexillium | 11.42 (2.15) | 7.29 (2.25) | 11.40 (2.35) | 7.88 (1.50) | 12.73 (1.66) | 7.75 (3.05) | 12.92 (1.47) | 8.50 (0.35) |
| Bovine enamel | 6.99 (1.26) | 8.19 (1.06) | 7.91 (0.69) | 7.10 (0.84) | 7.58 (0.76) | 7.58 (0.76) | 7.96 (1.01) | 2.08 (1.50) |
| Vitabloc MKII | 9.25 (2.60) | 12.55 (1.87) | 11.61 (6.01) | 15.14 (5.85) | 8.29 (1.55) | 12.38 (3.60) | 14.26 (2.04) | 10.42 (1.80) |
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