Three different adhesive systems; three different bond strength test methods

The aim of this study was to evaluate the efficacy of the microtensile, microshear and shear bond strength test methods to assess the bond strength of two self-etch adhesives and one etch&rinse adhesive on dentin.

Seventy-five extracted human molars were ground to expose their flat dentin surfaces and randomly assigned to one of three groups according to the type of test method (15 for microtensile, 15 for microshear, 45 for shear). Each of these groups was then assigned to three sub-groups according to the bonding systems (Clearfil SE Bond, Kuraray; G Bond, GC; Prime&Bond NT, Dentsply) used. Then, 15 specimens were prepared for each sub-group according to the test method employed (n = 15). After being stored in distilled water at 37°C for 24 h, the specimens were placed in a universal testing machine for three test methods and stressed at a crosshead speed of 0.5 mm/min. Mean bond strengths were analyzed using Kruskall-Wallis and Mann-Whitney U-tests at a significance level of p < 0.05.

The microtensile test had the highest bond strength (p = 0.046). Clearfil SE Bond and Prime&Bond NT produced significantly higher values than the G Bond in the microtensile bond test (p < 0.05), whereas no significant differences were found among the adhesives in the microshear bond test (p > 0.05). For the shear test, Clearfil SE Bond showed higher bond strength than Prime&Bond NT and G Bond (p < 0.05).

Bond strength to dentin depends on the material and the test method used.