In Vitro Shear Bond Strength of Self-etching Adhesives in Comparison to 4th and 5th Generation Adhesives

To determine the shear bond strength (SBS) of different established (Resulcin Aqua Prime & Monobond N: RA, Prompt L-Pop III: PLP) and experimental (AC-Bond: AC, AC-Bond + Desensitizer: ACD) self-etching adhesives in comparison to fourth (Optibond FL: FL) and fifth generation (Excite: EX, Gluma Comfort Bond: CB) adhesives. All adhesives were applied on flat enamel and dentin surfaces and light cured following manufacturers' directions. Tetric Ceram A2 composite cylinders 3.5 mm in diameter and 2.0 mm in height were sheared off (1 mm/min) after thermocycling (5 to 55°C, 5000x). The t-test (5% level, Bonferroni-correction) was used for statistical analysis. SBS in enamel: RA: 27.0 ± 5.8 MPa, PLP: 15.9 ± 3.4 MPa, AC: 28.1 ± 4.4 MPa, ACD: 22.2 ± 4.1 MPa, FL: 33.2 ± 3.2 MPa, EX: 30.5 ± 5.1 MPa, CB: 30.1 ± 3.7 MPa. SBS in dentin: RA: 25.8 ± 5.7 MPa, PLP: 20.7 ± 2.9 MPa, AC: 27.0 ± 4.5 MPa, ACD: 20.7 ± 3.7 MPa, FL: 34.4 ± 3.8 MPa, EX: 30.0 ± 4.6 MPa, CB: 27.9 ± 2.6 MPa. FL resulted in significantly (p 0.002) higher SBS in enamel and dentin than RA, AC, ACD, and PLP, and in higher SBS to dentin than CB. In enamel and dentin, RA performed significantly superior to PLP, but was not different from AC and ACD. EX and CB were both on the same level of significance as AC and RA, but showed superior results to ACD and PLP (enamel and dentin). PLP resulted in significantly lower SBS values in enamel and dentin than all the other materials investigated, except ACD in dentin, to which it was equivalent. Resulcin Aqua Prime & Monobond N and AC-Bond were not significantly different than established 5th generation products. AC-Bond + Desensitizer and Prompt L-Pop have significantly different SBS from established 4th and 5th generation products. Future studies are required to investigate marginal integrity to determine if self-etching adhesives are an adequate alternative to one- and multi-bottle systems. Keywords: self-etching adhesives, 6th generation, in vitro study, shear bond strength