Shear Bond Strength and Failure Mode of Different Dental Adhesive Systems

The study aimed to evaluate the shear bond strength (SBS) and to analyse the failure mode at the resindentine interface of different dental adhesive systems. A total of 75 sound premolar teeth were selected and randomly assigned into five different adhesive groups (n=15): OptiBond Solo (OBS, total-etch), OptiBond Versa (OBV, two-bottles, self-etch), Adhe SE Ivoclar (ADHE, two-bottles, self-etch), G-Bond (GB, one- bottle, selfetch), and OptiBond All in One (OBO, one-bottle, self-etch). The occlusal surface of each tooth was flattened and composite resin cylinder (4x2 mm) was built up on the flat dentine surface using a custom made mould. The specimens were then subjected to 500 thermal cycles between 5 °C and 55 °C and dwell time of 20s. The SBS test was conducted using a universal testing machine at a crosshead speed of 0.5 mm/min. Data were analyzed using one-way ANOVA and Dunnett T3 Test. Failure mode was determined as adhesive, cohesive or mixed mode using a stereomicroscope and the data were analyzed using Fisher s exact test. The total-etch (OBS) had significantly higher value of SBS than the two self-etch (ADHE and GB) adhesive systems. Within the self-etch systems, OBV showed significantly higher SBS value compared to ADHE and GB. There were no statistically significant differences between types of failure mode (p 0.05) and adhesive group. It can be concluded that the different compositions in the self-etch adhesive materials may contribute to the different SBS value. The failure modes detected within all tested groups did not show clinically important differences.