Bond strength of resin cements to dentin using universal bonding agents

Purpose: To determine the effect of new universal bonding agents on the bond strength of dual-cure resin cements to dentin. Methods: 140 extracted human third molars were mounted in dental stone and sectioned with a saw to remove coronal tooth structure. The teeth were randomly divided into seven groups of 20, based on the use of five universal bonding agents (All-Bond Universal; FuturaBond U; Prime&Bond Elect; Scotchbond Universal; Clearfil Universal) compared to two self-etch bonding agents (Clearfil SE Bond and Clearfil SE Bond 2). Each group was further divided into two equal subgroups of 10 specimens each with each subgroup tested with either self-or light-cure activation of the dual-cure resin cement (Calibra). The bonding agent was applied per manufacturers' instructions to the dentin surface of each specimen. The specimens were placed into a jig and resin cement was inserted into the mold to a height of 3-4 mm and light cured. Specimens were stored for 24 hours in 37 degrees C distilled water and tested in shear in a universal testing machine. A mean shear bond strength value (MPa) and standard deviation was determined per group. Results: Except for Clearfil Universal, the new simplified universal bonding agents resulted in significantly lower shear bond strength of the resin cement to dentin than the two-step, self-etching bonding agents Clearfil SE Bond or Clearfil SE Bond 2.