Effects of Application Modes on Dentine-Bond Strength of Universal Adhesives

Objectives: To compare the dentine microshear bond strength (µSBS) of four universal adhesives (UAs) applied in five application modes (self-etch; SE, etch-and-rinse; ER, double-time application; SDT, double-application; SDA or double-layer application; SDL).
Methods: Eighty sound human third molars were randomly divided according to UAs used (Scotchbond Universal; SBU, All-bond Universal; ABU, Clearfil Universal; CFU and G-Premio Bond; GPB) and five application modes resulted in twenty groups. Fifteen specimens per each group were assigned. The occlusal cusps were removed to expose dentine. Then, the adhesive for each group was applied following assigned mode and light cured. Tygon tubes were filled with resin composite and placed on dentine and then stored for 24hours in distilled water at 37°C. The specimens were µSBS tested and observed for fracture modes using stereo microscope. Data was analyzed using one-way ANOVA and two-way ANOVA with Bonferroni’s test (α = 0.05).
Results: The highest µSBS group was SBUSDL and the lowest was GPBSDL. When compared between application modes, SBU revealed significantly increased µSBS when SDT and SDL were applied as well as ABU when ER SDT, SDA, and SDL were applied while CFU and GPB had no difference. When compared between UAs, ABU revealed significantly higher µSBS than CFU and GPB when ER, SDT, SDA and SDL were applied and higher than SBU when ER and SDA were applied. SBU revealed significantly higher µSBS than CFU and GPB when SDT and SDL were applied. Different application modes and UAs significantly influenced µSBS.
Conclusions: The effects of application modes of UAs were material depended. Acidity, HEMA containing, fillers and solvent type of each UAs influenced the bond strength differently.