Does Multi-mode Strategy Affect Adhesion to Caries-affected Dentin?

Objectives: The aim of this study was to determine the micro-shear bond strength (μSBS) of universal adhesives to caries-affected (CAD) and sound dentin (SD) in self-etch (SE) and etch&rinse (ER) modes.
Methods: 54 extracted human third molars with occlusal caries were ground flat to expose both sound and caries-affected dentin using 180 SiC paper. Caries infected dentin was removed with 600-grit SiC paper using visual, tactile and caries-detecting dye methods. After standardizing the smear layer on the specimens with 600-grit SiC paper, SD and CAD specimens were divided into 6 groups (n=9); intermediate universal G-Premio Bond (GPSE, GPER; GC), ultra-mild universal Prime&Bond Universal (PBSE, PBER; Dentsply, Sirona); mild self-etch Clearfil SE Bond (CSE; Kuraray) and etch&rinse adhesive Adper Single Bond 2 (ASB; 3M ESPE) that were used as controls. Adhesives were applied according to the manufacturer's instructions and flowable resin composite was used for composite build-ups (Gaenial Universal Flo A2; GC) (1x1 mm) and polymerized (Demi Ultra; 1100mW/cm²). After 24 h of water storage at 37 ^οC, μSBS (Instron) was performed. Data were statistically analyzed using Tukey multiple comparison and independent t tests (p<0.05).
Results: Bonding to CAD was significantly lower than bonding to SD (p<0.05) for all the tested adhesives. CSE and ASB showed the highest, GPER and GPSE showed the lowest μSBS to SD and CAD (p=0.0001). There were no significant differences for PBER and PBSE in CAD (9.79±1.95; 9.42±2.15 p=0.688) and SD (19.51±2.87; 17.81±2.37 p=0.127) groups, however significant increase was observed for GPER than GPSE in CAD (7.10±1.76; 5.72±0.99 p=0.045) and SD (15.41±2.03; 11.06±1.76 p=0.0001).
Conclusions: Multi-mode strategy to sound and caries-affected dentin was shown to be material-dependent. Etch&rinse approach of intermediate universal adhesive to sound and caries-affected dentin could be beneficial for improved bonding performance. Similar bonding performance was observed for ultra-mild universal, mild self-etch and etch&rinse adhesives on caries-affected dentin.